Infectious diseases

“What’s in a name? That which we call a rose By any other name would smell as sweet.” — William Shakespeare, Romeo and Juliet; II, ii, 1-2; circa 1595 Comment: In 1948, MacCallum and colleagues published an article reporting a new mycobacterial infection in man,1 and later named the causative organism Mycobacterium ulcerans. In their article, they described six patients, five of whom came from the Bairnsdale district in Gippsland, Victoria. Three Bairnsdale general practitioners, Drs Alsop, Clay and Searls, had initially recognised a novel disease in their region and submitted pathological specimens to Melbourne University for diagnosis.2 Subsequently, the same disease was described in many different areas, mostly in Africa (“Buruli ulcer”). Each new outbreak tended to give rise to a new name; of all these, perhaps the most colourful is “Sik belong Sepik”, describing the infection as it occurs along the Sepik River in Papua New Guinea. In Victoria, where most Australian cases of M. ulcerans infection occur,3 we have continued to use the term “Bairnsdale ulcer” even though the main endemic areas are now the Bellarine and Mornington Peninsulas near Melbourne.3 Medical eponyms have a place for diseases that are poorly understood or have unknown causes, but it could be argued that the terms “Bairnsdale ulcer” and “Buruli ulcer” now belong in the annals of medical history. However, there are other considerations. In 1998, the World Health Organization launched the Global Buruli Ulcer Initiative.4 This successful advocacy raised the profile of this neglected disease and facilitated major improvements in diagnosis and treatment. For better or worse, “Buruli ulcer” has become the internationally recognised term for M. ulcerans infection, and we propose that we should now also adopt this name in Australia. While this should come as a relief to the good citizens of Bairnsdale and the Bellarine peninsula, what about those of Buruli in Uganda? Fortunately, their county has been renamed and is now known as the Nakasongola District.5

Paul D R Johnson · John A Hayman

To the Editor: Recent articles in the Journal referred to clinical characteristics of lesions caused by Mycobacterium ulcerans in Australia, and to recommendations and challenges in their management.1-3 Brazil may also be an endemic area of this devastating neglected but treatable disease. In developing countries, cases of Bairnsdale or Buruli ulcer (BU) can be misdiagnosed or underreported because neither the general public nor health care workers have sufficient knowledge about the disease, and because affected people usually have little contact with the health care system, or do not seek prompt treatment.4 Expensive tests like the polymerase chain reaction are not available to confirm all suspicious cases, and smears can give a low diagnostic yield; there are often minimal histopathological changes and absence of bacilli, particularly in patients with long-standing lesions previously treated with effective antimicrobial drugs.4 We report the case of a 65-year-old Brazilian woman with a 2-year history of BU in her extremities coexistent with osteomyelitis in the fourth cervical vertebra (Figure 1), and evidence of inadequate nutrition. Although she had received BCG vaccine as an infant, mycobacteria osteomyelitis developed in the site of an arthrodesis performed in 1998 to treat an accidental fracture.4,5 This patient had lived in a poor riverside rural area with a humid, hot climate. As in descriptions of Australian cases, our patient was much older than the age (5–15 years) at which most cases of M. ulcerans infection are reported in tropical and subtropical regions.1,2,4 Before her disease was characterised through positive cultures for M. ulcerans in samples from skin and bone lesions, the main differential diagnosis was ulcers resulting from fungal infection and leishmaniasis,4 conditions that are frequently seen in the region where she lived. The earlier skin lesions had appeared in May 2004 as papules and nodules, and evolved as painless, chronic, indolent ulcers with undermined edges.2,4 Despite treatment in another hospital that included surgery as well as medical therapy with rifamycin, aminoglycoside and quinolone antibiotics, the disease recurred. On admission to our hospital in August 2006, she had an extensive ulcer on her left arm in addition to scars on the right inner thigh (Figure 2). After nearly 2 months of hospitalisation, the patient was discharged to continue antimicrobial therapy with outpatient follow-up. Despite this, the lesions are healing very slowly. 1: X-ray image of osteomyelitis (arrows) affecting the body of the fourth cervical vertebra. 2: Extensive ulcer on the left arm (arrows; A) and brown pigmented scars on the inner right thigh (B).

Vitorino M dos Santos · Flávio L Noronha · Érica C Vicentina · Camila C Lima

A 32-year-old farmer from rural north-west India presented with a history of paroxysms of cough with expectoration. He owned livestock (hens, goats, cattle and dogs) and lived alongside them. Physical examination was unremarkable except for reduced air entry in the left infra-axillary and infrascapular area. A chest x-ray (Box, A) showed a large, thin-walled cavity containing membranes in the lower lobe of the left lung, together with a left pleural effusion. A contrast-enhanced computed tomography scan of the chest (Box, B) revealed a cyst in the left lower lobe of the lung containing a freely floating endocyst (the “waterlily sign”). The diagnosis of Echinococcus infection (hydatid cyst) was confirmed by positive serology. The waterlily sign, although rarely seen, is pathognomonic for Echinococcus. A: Chest x-ray showing a large thin-walled cavity containing freely floating endocyst membranes (arrow). B: Contrast-enhanced computed tomography scan of the chest showing a cyst (arrow) in the left lower lobe of the lung containing a freely floating endocyst (the “waterlily sign”).

Maneesh Khanna MD · Sandeep Chauhan MD · Usha Dalal MS · Sarabmeet S Lehl MD

To the Editor: In reference to the letter by Kennedy et al, reporting two patients who tested positive to human T-lymphotropic virus I/II (HTLV-I/HTLV-II) antibodies after administration of the intravenous immunoglobulin, Octagam (Octapharma Australia, Sydney, NSW),1 the Therapeutic Goods Administration (TGA) would submit that: This product was accepted for review by the TGA at a time when plasma products sourced from overseas had to demonstrate superiority over the local product. This requirement was fulfilled by Octagam on grounds that included pathogen safety issues. HTLV-I and HTLV-II are entirely cell-associated viruses and are thus irrelevant to the safety of plasma derivatives. They are in a group of pathogens for which risks, implied by epidemiological factors, apply to cellular but not to plasma products. Another common example is malaria. The Australian plasma pool includes donations from individuals who are at risk of transmitting malaria, so their cells are not used but their plasma is used for fractionation. This situation is well understood and managed by regulators, none of whose standards internationally include the need to test plasma donors for HTLV-I/HTLV-II infection. As the bulk of Australia’s fractionation pool is derived as a by-product of whole blood, blood is tested for HTLV-I/HTLV-II in this country, but it is not a mandatory requirement in Australia or anywhere else. The exclusion of antibody from the plasma pool, as occurs for HTLV-I/HTLV-II in Australia, may actually lead to the loss of potentially protective antibodies, which may well have a therapeutic effect in protecting patients from HTLV-I/HTLV-II infection.2 Such considerations apply, for example, in the requirements of the Food and Drug Administration in the United States for source plasma for fractionation. The requirements take care to allow the inclusion of antibody-positive units for some viruses that would be excluded from blood transfusion. The incident referred to by Kennedy et al was appropriately reported to the TGA’s Adverse Drug Reactions Unit, which concluded that this was not an adverse event. A Northern Territory Government document on HTLV reports: “In Central Australia the prevalence of HTLV-I is estimated to be up to 14%, compared to 4.7% in the Northern Territory cattle country . . .”3 The residual risk of transmission of HTLV-I/HTLV-II infection, while low,4 clearly varies across the potential donor population, and comparisons that are irrelevant in relation to the safety of specific products would appear to be unwise. It is recommended that practitioners seeking to assess causality in putative infectious disease transmission by plasma products follow rigorous scientific processes, such as those recommended by the German regulatory authority.5

Albert Farrugia

A young male immigrant from Syria with a vasculitic-appearing leg rash, asymmetrical polyarthritis, microscopic haematuria, and raised inflammatory markers was provisionally diagnosed with Henoch–Schönlein purpura. Skin biopsy showed leukocytoclastic vasculitis. Low-grade fevers persisted despite non-steroidal anti-inflammatory therapy, and Brucella sp. was subsequently grown from both blood and synovial fluid aspirates. Further tests gave positive results for B. abortus, and triple antibiotic therapy produced a rapid clinical response. Cutaneous vasculitis has rarely been described in brucellosis, and this is the first report in the English medical literature of brucellosis mimicking Henoch–Schönlein purpura. Clinical recordA 22-year-old man presented with arthralgia, fevers, weight loss and a leg rash. His medical history was unremarkable, and he was taking no medications. He had emigrated from Syria 2 months before to be with his family in Australia. He had been sexually active before emigration, but did not describe any illness consistent with a sexually transmitted disease. One month before presentation, the patient had left elbow pain and swelling, with subsequent involvement of the left knee, right ankle and foot. One week later, he developed a dry cough and night sweats. The non-pruritic leg rash started 1 week before presentation, ascending gradually to his knees. He had lost 8 kg in weight over the preceding weeks. Blood tests performed 2 weeks before admission showed: C-reactive protein (CRP) level, 18 mg/L (reference range [RR], 0–8 mg/L); erythrocyte sedimentation rate (ESR), 32 mm/h (RR, 1–20 mm/h); and a raised rheumatoid factor of 50 IU/mL (RR, < 40 IU/mL). The patient presented to the emergency department with progressive leg rash and difficulty walking because of knee pain. At initial examination he had a temperature of 38°C, and an erythematous maculopapular rash with a vasculitic appearance on his feet, with discrete lesions on the leg distally and a more confluent appearance around both knees. There was an oligoarthritis involving the left elbow, both knees, right ankle and right metatarsophalangeal joints, as well as axillary lymphadenopathy. Urinalysis showed a large amount of blood, with no dysmorphic cells or casts. The provisional diagnosis was Henoch–Schönlein purpura. Laboratory investigations showed a CRP level of 91 mg/L, an ESR of 78 mm/h, and a γ-glutamyl transferase (GGT) level of 118 U/L (RR, < 61 U/L), with other liver tests, a full blood count and renal function tests giving normal results. A blood and urinary vasculitic screen, including antinuclear antibody and serum complement tests, gave negative results, apart from high levels of anti-dsDNA antibodies (> 100 IU/mL; RR, 0–7 IU/mL). Other tests for an infectious cause including HIV, hepatitis B, hepatitis C, Epstein–Barr virus, cytomegalovirus, syphilis and streptococcal antigens gave negative results. His serum angiotensinogen-converting enzyme level was not raised. A 3 mL aspirate of blood-stained synovial fluid from the right knee was non-inflammatory. Skin biopsy from the leg showed leukocytoclastic vasculitis with IgA immunofluorescence of dermal vessels, consistent with Henoch–Schönlein purpura, and a Gram stain gave negative results. Over the next few days, the oligoarthritis improved with non-steroidal anti-inflammatory therapy, but low-grade fevers continued and a repeat test of his CRP level showed it was still raised (37 mg/L). The haematuria had resolved. Subsequently, microscopy and culture of both blood (aerobic bottle) and synovial fluid samples showed gram-negative rods, which were identified as belonging to the genus Brucella. Antibody testing for Brucella abortus was highly positive (agglutinins, > 1280). Computed tomography scanning of the thorax and abdomen revealed axillary, mesenteric and para-aortic lymphadenopathy, and a radionuclide bone scan showed peripheral arthritis in several sites with no spinal involvement. Transoesophageal echocardiogram showed no evidence of endocarditis. On further questioning, the source of Brucella organisms was thought to be cheese or yoghurt made from unpasteurised milk, consumed before emigrating to Australia. There were no close contacts of the patient who were unwell. Both the hospital’s Infection Control Team and the Sydney South West Public Health Unit (Liverpool Hospital) were notified of the case. The patient was given triple antibiotic therapy of gentamicin, doxycycline and rifampicin, which led to further improvement, and he was discharged after 2 weeks. At discharge, he was fully ambulant, with resolution of joint pain, fevers and rash. He completed a course of gentamicin for 3 weeks and oral antibiotics for 6 weeks. After taking antibiotics for 3 weeks, the CRP level had normalised and the GGT level was still raised at 126 U/L. Repeat tests for anti-dsDNA antibodies at 6 months gave normal results (3 kIU/L). DiscussionBrucella melitensis was first isolated in 1887 by the Australian-born microbiologist, David Bruce, from human spleens of patients suffering from Malta fever or undulant fever. Brucellae are gram-negative, facultative intracellular bacteria, which represent a major global zoonosis.1 Brucellosis is a systemic infection that can involve any organ.2 The different Brucella species are named for their preferred animal hosts. B. melitensis (principally goats and sheep) and to a lesser extent B. abortus (particularly cows) are the two species most closely associated with human infection because of higher virulence compared with other species.3 High-risk foods associated with acquisition of Brucella spp. include unpasteurised dairy products, particularly raw milk, soft cheese, butter and ice cream.3 Brucellosis is rarely transmissible by humans, and the major infectious risk relates to infection from a common food or animal tissue source.2 Brucellosis remains a significant global disease affecting the Middle East, Africa, the Indian subcontinent, Mexico and Central America, as well as parts of Europe including Spain, Greece and Turkey. However, eradication of brucellosis has been effective in certain countries such as Australia, New Zealand and the United Kingdom through stringent agricultural practice.2-4 While animal vaccines are available, there is no human vaccine. As seen in our patient, brucellosis most commonly affects adolescents and young adults. The onset of symptoms is generally 2–4 weeks after inoculation, although with chronic infection a pattern of undulant fever is described.2 Clinical manifestations of brucellosis are protean. Cutaneous lesions in brucellosis are unusual,5 and cutaneous vasculitis has only rarely been reported.6,7 Although dermal IgA deposits have been rarely described in association with Brucella-associated vasculitic rash,6 this is the first case of brucellosis mimicking Henoch–Schönlein purpura. Skin lesions are usually sterile,6,7 but B. melitensis has been cultured from a skin biopsy in a patient with arthritis and papulonodular rash.5 In contrast to skin disease, osteoarticular involvement is common.4 The major osteoarticular manifestations include peripheral arthritis, sacroiliitis and spondylitis. Most frequently involved are the hip, knee and ankle joints. Although a large-joint monoarthritis is the usual presentation of peripheral arthritis, both oligoarthritis and a rheumatoid-like pattern occur.4 In many cases of monoarthritis, Brucella spp. is not cultured from synovial fluid.8 In polyarthritis, the frequency of bacterial isolation from synovial fluid is unclear.9,10 Diagnosis of brucellosis is based on tissue-specific and serological tests. Definitive diagnosis of brucellosis is by isolation of bacteria from body tissue, including blood, bone marrow or synovial fluid. Presumptive diagnosis can be made by specific antibody tests against bacterial lipopolysaccharide or other bacterial antigens. Both high or rising titres of antibodies may aid in the diagnosis.2 Treatment of brucellosis is most effective with combination antibiotic therapy, as monotherapy often results in relapse. Effective antibiotics are those that can penetrate macrophages and work in an acidic environment. Antibiotics generally employed include: gentamicin, doxycycline, rifampicin, co-trimoxazole, quinolones and streptomycin.3 Oral treatment regimens are often based around doxycycline, and the duration of oral therapy is usually 6 weeks. Neurobrucellosis and endocarditis usually require longer treatment periods. Incomplete duration of therapy or an inadequate treatment regimen can result in disease relapse, and chronic infections are usually associated with deep foci of infection.2 This case highlights the diagnostic variability of the presentation of brucellosis and its ability to mimic systemic vasculitic disease, in particular Henoch–Schönlein purpura. This is of particular importance in patients who have recently emigrated from or travelled to high prevalence areas, especially with exposure to unpasteurised animal products.

David Massasso MB BS, BSc, FRACP · Kathryn Gibson BM BCh, FRACP, PhD

Clinical record A 23-year-old woman presented to the emergency department with acute radicular lower back pain that became apparent when she was lifting books. She had normal blood pressure and 100% oxygen saturation breathing room air, but her heart rate was 110 beats/min and she had a temperature of 38.4°C. Inexplicably, she was discharged with a diagnosis of mechanical back pain. She presented again 2 days later with back pain, increasing shortness of breath, vomiting, myalgia, fever and sweating. She had also developed a dry cough and anterior pleuritic chest pain. There was an erythematous lesion on her left elbow. She and other family members had a history of recurrent furunculosis. When examined on admission, the patient was tachycardic (heart rate, 160 beats/min), hypotensive (blood pressure, 80/50 mmHg) and hyperpnoeic (respiratory rate, 32 breaths/min), with an oxygen saturation of 100% on a non-rebreather mask with oxygen flow at 15 L/min. She was febrile, with a temperature of 38.2°C, and had a furuncle on her left elbow. She had tenderness in the right upper quadrant; the spleen was not palpable. There was midline and left paraspinal tenderness over T8/9. There was no tampon in situ. Initial investigations showed a predominantly neutrophilic leukocytosis (18.4 × 109 cells/L [reference range (RR), 3.5–11 × 109 cells/L]); coagulopathy (prothrombin time, 20 s [RR, 9–14 s]; activated partial thromboplastin time, 40 s [RR, 25–38 s]); thrombocytopenia (platelet count, 59 × 109/L [RR, 140–400 × 109/L]); renal dysfunction (urea level, 14.2 mmol/L [RR, 3–8 mmol/L]; creatinine level, 172 μmol/L [RR, 50–100 μmol/L]); and an elevated serum troponin I level (1.4 μg/L [RR, < 0.2 μg/L]). A chest x-ray showed bilateral multilobar consolidation. Initial therapy included large-volume fluid resuscitation, a noradrenaline infusion, intravenous hydrocortisone and empirical intravenous antibiotics (3.1 g ticarcillin/clavulanate, 400 mg gentamicin and 500 mg azithromycin, within 50 minutes of arrival). Subsequently 2 g dicloxacillin was administered intravenously. The patient required intubation and mechanical ventilation 6 hours after admission, due to markedly deteriorating respiratory function. At this time, arterial blood gas results measured with the patient on 100% oxygen were: pH, 7.13 (RR, 7.35–7.45); partial pressure of carbon dioxide (Paco2), 52 mmHg (RR, 35–45 mmHg); Pao2, 237 mmHg (RR, 75–100 mmHg); base deficit, –12.3 mmol/L (RR, –3 to 3 mmol/L); and bicarbonate, 16 mmol/L (RR, 22–33 mmol/L). A computed tomography scan revealed multiple small areas of airspace opacification in a perivascular distribution, as well as bilateral extensive lower-lobe consolidation. Nine hours after admission, in view of worsening shock, drotrecogin alpha (activated protein C) and vasopressin were commenced. Despite a high-dose infusion of noradrenaline and adrenaline, the patient’s circulatory status continued to deteriorate. Staphylococcus was grown from initial blood cultures after 14 hours, and intravenous vancomycin 1000 mg was administered. Sixteen hours after admission, the patient had an episode of ventricular tachycardia, which reverted to sinus rhythm after a single precordial thump. However, ventricular tachycardia recurred and progressed to asystole. The patient died 17 hours after presentation, despite resuscitation. Subsequently, methicillin-resistant S. aureus (MRSA) was grown from blood cultures, endotracheal aspirates, and furuncle swabs and biopsies. The organism was sensitive to erythromycin, clindamycin, gentamicin, tetracycline, ciprofloxacin and vancomycin. Isolates were typed using a real-time polymerase chain reaction method based on single nucleotide polymorphisms (SNP) of the core genome and the presence or absence of variable genes, including the gene for Panton–Valentine leukocidin (pvl).1 All isolates had an SNP and variable gene profile characteristic of the Queensland clone (ST93-MRSA-IV) of community-associated MRSA (CA-MRSA), including the presence of pvl. Queensland clone CA-MRSA was also isolated from nose swabs subsequently collected from three family members, two of whom had suffered from recurrent furunculosis. Postmortem examination showed that the principal pathology lay in the lungs and myocardium. The lungs showed multiple foci of bronchopneumonia, many coalescing to form extensive areas of lobar pneumonia. However, the most striking feature seen on histology was involvement of the pulmonary vasculature by staphylococcal septicaemia. Staphylococci had invaded the walls of multiple blood vessels, producing a florid vasculitis with subsequent secondary thrombosis of the involved vessels (Figure). This process involved both large and small vessels to such an extent that a lethal degree of bilateral arterial thrombosis had developed. The larger thrombosed vessels were obvious at macroscopic examination of lung slices. Multiple small thrombi were seen on microscopy. The myocardium showed focal abscesses containing staphylococcal colonies. Adjacent myocardial fibres showed necrosis, which correlated with the patient’s raised troponin level. The other organs of the body were remarkably free of sepsis, the spleen was normal, and the spinal column showed no evidence of osteomyelitis. A furuncle on the left elbow was confirmed. Virulent strains of methicillin-resistant Staphylococcus aureus (MRSA) have recently emerged in community settings around the world (including many parts of Australia)2 and are causing community-acquired infection with increasing frequency.3 Most of the virulent strains carry the genes for producing Panton–Valentine leukocidin (PVL), a potent necrotising toxin. They most commonly cause primary skin and soft tissue infections such as furuncles and abscesses, but can also give rise to severe invasive conditions, including necrotising pneumonia.4 While uncommon, necrotising pneumonia is associated with a high mortality rate. In Australia, two major strains of PVL-positive, community-associated MRSA (CA-MRSA) are currently circulating: the Queensland (QLD) clone and the south-west Pacific (SWP) clone. Currently, these strains predominate among CA-MRSA in Queensland, New South Wales and the Australian Capital Territory, while in other states, PVL-negative strains are more common.2 Lessons from practice A history of recurrent furunculosis in a patient or in family members may precede severe Staphylococcus aureus sepsis, including necrotising pneumonia. Patients with recurrent infection due to S. aureus should be tested for persistent nasal carriage. Treatment aimed at eradication could be considered. The prevalence of virulent strains of community-associated methicillin-resistant S. aureus (CA-MRSA) is increasing in many parts of Australia. Knowledge of local prevalence would be valuable in guiding empirical treatment. In communities where CA-MRSA is prevalent, suspected severe sepsis due to S. aureus should be treated with a combination of vancomycin and one of dicloxacillin, flucloxacillin or cephalothin until culture and susceptibility results are available. Necrotising pneumonia due to PVL-positive S. aureus is often rapidly fatal, as in the case described here. A study by Gillet et al recorded a mortality rate of 37% within 48 hours of presentation.5 A significant association with preceding furunculosis was also noted. Most cases occurred in otherwise healthy children and young adults. A recently reported fatal case of CA-MRSA necrotising pneumonia in an Indigenous person was also in a previously healthy young adult.6 The patient in our case had a history of recurrent furunculosis and a furuncle on her elbow at presentation, both commonly caused by PVL-positive S. aureus. Two family members had also suffered from recurrent furunculosis. All isolates from the patient and from nose swabs of three family members belonged to the QLD clone. QLD and SWP clones are frequently sensitive to numerous non-β-lactam antimicrobials.2 Agents such as clindamycin and cotrimoxazole may be used to treat mild-to-moderate CA-MRSA infections such as furunculosis, depending on the organism’s susceptibility.7 Agents that act against protein synthesis (and therefore toxin production) have a theoretical advantage in the treatment of toxin-related infectious syndromes, but good clinical studies in this area are lacking. The use of clindamycin for treating invasive CA-MRSA infections is supported by one retrospective study in children.8 Linezolid, a new agent also active against protein synthesis, has been shown to be superior to vancomycin, but only in complicated skin and soft tissue infections.9 Use of one of these agents, perhaps in combination with established anti-staphylococcal antibiotics, is worthy of prospective study. The current national recommendation for treating suspected MRSA pneumonia is to administer vancomycin together with a β-lactam antibiotic (dicloxacillin, flucloxacillin or cephalothin) until susceptibility data are known.7 The severity of this case and rapidity of progression make it unlikely that more appropriate antibiotic therapy would have led to survival. Indeed, azithromycin, which was administered soon after admission, is active against erythromycin-sensitive strains of S. aureus. Nevertheless, early optimum antimicrobial treatment will give the best chance of survival. The possibility of MRSA pneumonia should be considered in the context of severe community-acquired pneumonia, particularly in children or young adults, and especially if there is evidence of preceding staphylococcal infection, such as folliculitis or furunculosis. Histological section of the patient’s lung at autopsy The section shows confluent staphylococcal bronchopneumonia with invasion of vessels in the lungs, producing a florid vasculitis (arrow). Secondary thrombosis is occluding the pulmonary vascular system. (Haematoxylin–eosin stain; original magnification × 100)

David C Risson MB BS, BVSc · Enda D O’Connor MB BCh, MRCP(Irl), FJFICM · Roger W Guard FRCPA · Jacqueline M Schooneveldt MAppSci, MASM, GCM · Graeme R Nimmo FRCPA, FASM, MPH

Entamoeba histolytica is one of the most common parasitic infections worldwide, infecting about 50 million people and resulting in 40 000–100 000 deaths a year. In Australia, people at risk of infection include immigrants, travellers returning from countries of high endemicity, Indigenous people, and men who have sex with men. Clinical manifestations range from asymptomatic carriage to invasive disease. Amoebic colitis and amoebic liver abscess are the most common invasive manifestations observed in Australia. Diagnosis depends on a high index of suspicion and laboratory investigations. Molecular methods (using the polymerase chain reaction) are the most sensitive for identifying and differentiating Entamoeba species. Treatment should always include a luminal agent to eradicate colonisation, prevent spread and/or reduce the risk of invasive disease. Medical therapy can successfully cure invasive disease, including amoebic liver abscesses.

Sebastiaan J van Hal MB ChB · Damien J Stark BSc, PhD · Rashmi Fotedar PhD · Debbie Marriott FRACP, FRCPA · John T Ellis PhD, DSC · Jock L Harkness FRCPA

Clinical record A 24-year-old man was referred to the hospital outpatient infectious diseases clinic with a 3-month history of a non-healing ulcer on his left forearm. He had just returned from a 1-year tour of South America, where his accommodation included camping on forest floors. He reported receiving many insect bites. Several weeks after travelling through rainforest in Peru and Ecuador, he noticed a painless papule on his left forearm. By the time he attended a hospital in Salvador, Brazil, 3 months later, the lesion had progressed to a 3 cm diameter ulcer. A Montenegro test was positive, and cutaneous leishmaniasis (CL) was diagnosed. Declining treatment, the man completed his travels and returned to Sydney a month later for further management. Examination showed a painless, full-thickness 4 cm × 3 cm ulcer with a granulating base and raised edges on the patient’s forearm (Figure A). There was no regional lymphadenopathy. Tissue impression smears and multiple 3 mm punch biopsies from the ulcer edge confirmed the presence of inflammatory cells and necrotising granulomas in the dermis. Despite prolonged examination of Giemsa-stained sections, no intracellular parasites were detected. An ulcer edge biopsy sent for polymerase chain reaction (PCR) analysis was negative for Leishmania DNA. However, Leishmania promastigotes were identified on Day 7 from culture of an ulcer biopsy on Novy–McNeal–Nicolle medium (Figure B). PCR analysis confirmed the presence of L. braziliensis promastigotes. Specifically, DNA was extracted from a tissue biopsy and from cultured promastigotes using a DNA Mini Kit (QIAGEN, Germany) according to the manufacturer’s instructions. A PCR restriction fragment length polymorphism (RFLP) analysis targeting both the end of the ribosomal small subunit and the whole internal transcribed spacer 1 region was performed, as described elsewhere.1,2 Both techniques gave banding patterns consistent with L. braziliensis from the cultured promastigotes (Figure C), confirming the diagnosis. The patient was given amphotericin B (1 mg/kg) on alternate days via a peripherally inserted central catheter after normal-saline prehydration and electrolyte supplementation. In total, 1.2 g amphotericin was administered over 30 days and well tolerated. The patient required dietary potassium and magnesium supplementation. He developed reversible renal impairment and anaemia and associated fatigue. By the end of treatment, his serum creatinine level had peaked at 251 μmol/L (reference range [RR], < 110 μmol/L), his serum urea level was 18.7 mmol/L (RR, < 7.1 mmol/L) and his haemoglobin [Hb] level was 113 g/L (RR, 130–180 g/L). These parameters had normalised 3 months later (serum creatinine, 100 μmol/L; creatinine clearance, 2.4 mL/s [RR, 1.5–2.0 mL/s]; Hb, 133 g/L). Throughout treatment and follow-up, the patient attended as an outpatient and was able to continue his regular employment. His ulcer healed with a typical paper-thin scar (Figure D). Such a scar is usually flat, atrophic and depigmented (similar to a burns scar), and persists lifelong. Leishmania species are dimorphic protozoan parasites transmitted by female blood-sucking sandflies to mammalian hosts, in which they become obligate intra-macrophage parasites. More than 25 species of Leishmania are capable of producing disease in humans and animal reservoirs in tropical and subtropical regions.3 About 1.5 million new cases are documented each year in humans, and over 350 million people live in areas of active parasite transmission.4 Leishmaniasis is one of the top five diseases targeted by the World Health Organization Special Programme for Research and Training in Tropical Diseases (http://www.who.int/tdr/index.html). Whether leishmaniasis appears in cutaneous, mucosal or visceral form is largely determined by the parasite species. The strength of the host’s cell-mediated immunity determines whether infection remains subclinical, is self-healing, or becomes disseminated, when death may result.4 Acquired cell-mediated immunity may be partially protective against reinfection and last long-term, but does not always prevent recurrences of infection or metastasis of parasites, particularly if immunity wanes, as happens in advanced HIV infection. Glossary Montenegro or leishmanin skin test: Leishmania antigen from a preparation of cultured promastigotes is injected intradermally. A typical red induration, maximal at 48 hours, indicates a cell-mediated response to Leishmania in active cutaneous infection, a positive test result which may persist for life. Novy–McNeal–Nicolle medium: an axenic culture medium comprised of a blood agar slope with a saline overlay, incubated at 25°C. Promastigote: The morphological stage in the life cycle of certain trypanosomatid protozoa in which the cell has an elongated shape, with a round nucleus, rod-shaped kinetoplast and single long flagellum. Leishmaniasis is categorised geographically as “New World” (Central and South America, and Texas in the United States) or “Old World” (the Mediterranean basin, the Middle East and Africa). Lutzomyia is the sandfly vector in the New World and Phlebotomus in the Old World.3 New World CL may present as an ulcer that remains localised (if caused by species such as L. mexicana) or may later disseminate (if caused by species such as L. amazonensis or L. braziliensis). L. braziliensis is the most prevalent in the rainforests of South America, where various forest mammals (including anteaters, sloths and possums) act as animal reservoirs for the disease.3 Infection with L. braziliensis results in slow-healing skin ulcers. These may be further complicated by mucosal disease, the incidence of which is about 3% in patients living in areas of endemicity.5 Mucosal leishmaniasis, which may appear from several months to decades after the initial infection, progressively destroys the oronasopharyngeal mucosa and underlying cartilaginous facial and upper airway structures.3-5 Without treatment, an affected person may die from secondary infection or airway compromise. Thus, treatment of cutaneous L. braziliensis infection is aimed at reducing the risk of progression to mucosal leishmaniasis. There have been few controlled trials to determine the optimal management for L. braziliensis infection.5,6 Intravenous pentavalent antimony, which has traditionally been used to treat all forms of leishmaniasis since 1915, is associated with serious side effects, including cardiotoxicity and sudden death. Additionally, recent studies have shown it to have reduced efficacy for treatment of CL.6,7 Amphotericin preparations, which are more effective for treating visceral and mucosal leishmaniasis, also look promising for treating New World CL.7 However, amphotericin B is also frequently associated with toxicity, including infusion-related fever, nausea and chills (these may be reduced with paracetamol premedication); normochromic, normocytic anaemia; and reversible nephrotoxicity, manifest as elevated serum creatinine levels and electrolyte loss (these can be managed by prehydration with normal saline and by electrolyte supplementation). Delivering amphtotericin in liposomal form lowers the risk of nephrotoxicity, but there is less experience with this preparation in treating leishmaniasis and the cost is significantly greater than conventional amphotericin B. The standard dosage of amphotericin B for treating New World CL is 0.5–1.0 mg/kg per day, usually for 10 to 20 doses. It needs to be given via a central vein. A peripherally inserted central catheter enables the drug to be administered readily to outpatients. As different Leishmania species may coexist in the same region, the species causing the infection needs to be identified from the lesion to determine appropriate therapy. Specifically, if a non-metastasising Leishmania species (such as L. mexicana) was identified as the cause of a cutaneous ulcer, systemic therapy would be avoided. Lessons from practice Cutaneous leishmaniasis (CL) is increasingly seen in travellers and must be considered in the differential diagnosis of ulcers in travellers returning from regions of endemicity. New World CL may be difficult to diagnose on histopathology alone, and attempts should be made to culture the organism to facilitate diagnosis. Polymerase chain reaction analysis, now available in Australia, is necessary to speciate the Leishmania infection to direct appropriate management. Amphotericin B is an effective alternative to more toxic traditional treatment with pentavalent antimony. PCR is currently the method of choice for speciating all forms of leishmaniasis, as it has a high sensitivity and gives a species-specific diagnosis, facilitating specific treatment.1,2 To increase PCR sensitivity, the yield of diagnostic material can be enhanced by culturing biopsy specimens in vitro. In our RFLP analysis, the species-specific bands visualised in agarose gels allowed unequi-vocal differentiation of the isolate. Both assays targeted different loci and gave concurrent results. This is the first time, to our knowledge, that PCR speciation of Leishmania has been done in Australia. Previously, isolates have been sent for speciation to specialised laboratories overseas. Although mucosal leishmaniasis is rarely reported in travellers returning from areas of endemicity, the incidence has increased as travel to Latin America has become more common. Observed cases of New World CL have doubled in The Netherlands and tripled in the United Kingdom in the past decade.8 Imported cases of leishmaniasis, including New World CL, have been reported in Australia.9,10 Australia and the Pacific region have long been considered free of endemic Leishmania species4 and suitable sandfly vectors, thus preventing locally acquired leishmaniasis. However, locally acquired CL has recently been reported in Australian kangaroos.11 Molecular analysis of the isolates confirmed the genus Leishmania, but was suggestive of a novel species. This finding raises questions about the vector, possible unrecognised human transmission in Australia, and even potential endemic establishment of imported Leishmania. In conclusion, New World leishmaniasis is becoming more frequently reported among travellers, and the diagnosis must be considered in any traveller with a cutaneous ulcer who has come from an area of Leishmania endemicity. PCR speciation is necessary to optimise appropriate management of this potentially serious infection. Direct inoculation of tissue specimens into a Leishmania-specific culture medium may increase the yield of diagnostic material and thus enhance PCR sensitivity. Our case illustrates that amphotericin is an effective treatment for New World CL (although associated with reversible toxicity) and that an affected patient can be managed successfully as an outpatient under close supervision. A: Non-healing New World cutaneous leishmaniasis ulcer on the left forearm. B: Metacyclic Leishmania promastigotes in culture medium, Day 7. The parasites have a characteristic coiled, highly motile flagellum at the apical end of an elongated body (10–20 mm in length) containing a round nucleus and rod-shaped kinetoplast. C: Molecular banding pattern in agarose gel after PCR analysis. The banding pattern resulting from restriction fragment length polymorphism PCR analysis was consistent with Leishmania braziliensis DNA (M: a commercial 100-base-pair molecular marker [EZ Load 100 bp molecular ruler; Bio-Rad Laboratories, Hercules, Calif, USA]; 1: L. braziliensis control strain; 2: patient sample). D: Healed ulcer, 4 weeks after treatment with amphotericin B.

Pamela Konecny MB BS, MD · Damien J Stark MSc, PhD, FASM

To the Editor: In their report of Hendra virus infection acquired by a veterinarian from an infected horse, Hanna et al1 mention that the likely reservoir for this virus is fruit bats (Pteropus spp.), and suggest that transmission of the virus to horses may be via contamination of pasture by birth products from fruit bats. During 5 years of fieldwork in north-eastern Australia for my PhD thesis on Toxocara pteropodis, an intestinal roundworm of flying foxes,2 which included hundreds of hours observing fruit bats in their natural habitats, not once did I come across a case of natural birth or abortion in fruit bats away from their communal roosts (“camps”), which were always within pockets of dense forest, such as mangrove, eucalyptus or melaleuca swamps. Furthermore, the three coastal fruit bat species exhibited a short, well defined birthing season, generally over 3 weeks from late October through to November. The birthing season of the wide-ranging, inland little red flying fox, P. scapulatus, is 6 months out of phase with this; it produces its young in May3 in remote inland camps. During birth, which is a short process lasting usually less than an hour, the mother bat remains alone, quite separate from and ignored by her neighbours. All my observations of flying fox births were during daylight hours, and in the camps. While it is possible that an individual female might give birth away from her camp while out feeding at night, this would seem to be such an isolated event as to exclude it from being a reliable, and therefore major, transmission route for the virus. Moreover, the first recorded cases of equine and human infection occurred in the month of September,1 further diminishing the likelihood of birth products being the mode of transmission from bats. On the other hand, while feeding in mango trees or on other exotic or native fruits and blossoms growing in horse paddocks, these bats do defecate and urinate frequently; this, to my mind, may be a more likely infection route. Resting in camps, individual bats urinate indiscriminately, contaminating any neighbours roosting below. While out collecting flying foxes for my research, I found it impossible to avoid aerial contamination by their excrement — although I do not recall ever experiencing symptoms suggestive of Hendra virus infection.

Paul Prociv

To the Editor: Improving clinical efficiency helps sexual health services deal with the demands of increasing rates of sexually transmitted infections.1,2 Many Australian sexual health centres require all clients to return in person to obtain their HIV test results; legislation only requires those who test positive to return in person.3 Giving HIV test results by phone to low-risk clients may improve efficiency. We determined the proportion of women testing positive for HIV infection at Melbourne Sexual Health Centre (MSHC) between 1 January 1996 and 1 January 2006, and reviewed the files of those who tested positive to determine their risk factors for HIV acquisition. In this period, 16 655 women were tested for HIV and 48 (0.29%) tested positive. For 11 of these 48 women (0.07%; 95% CI, 0.027%–0.10%), this was their first positive test. Six had been born in a high-prevalence country4 and had had sexual contact in those countries (two in South Africa, one in Ethiopia, one in Zimbabwe, one in Kenya, and one in Thailand); two had a sexual partner with HIV; one had had sex with a resident of a high-prevalence country (Thailand); one had had sexual contact in Australia with a man from a high-prevalence country (South Africa); and one had had sex with a bisexual man. All these risk factors were recorded in the patient’s history at the time of initial testing. Of the 37 women who tested positive and whose initial HIV test was performed elsewhere, risk factors were documented for 34. Thirty-one women (91%) had similar risk factors to the 11 who had first tested positive at MSHC. All three women without identified risk factors at the time of testing subsequently discovered their male partners were known to have HIV. We found that fewer than one in 1000 women attending MSHC tested positive for the first time, and all who did had clear risk factors. The upper 95% CI for testing positive among those without risk factors (ie, none in 16 655) was also extremely low and in the order of 1 in 1000. In the light of these findings, it is difficult to justify providing all results in person. MSHC now provides HIV test results by telephone to women without risk factors. Women with unexpected, indeterminate or positive results are recalled. This requires sensitive management to minimise stress and anxiety.

Carol A Hopkins · Rosey A Cummings · Tim R H Read · Christopher K Fairley

The current whole-cell vaccine and protocol for Q fever prophylaxis are effective At the end of 2006, the Australian Ministers for Health and Agriculture announced funding for an upgraded facility to allow CSL Limited to recommence production of the Q fever vaccine (Q-Vax) and comply with changed biocontainment regulations.1 Production of the vaccine had ceased at the end of 2005 because of inability to meet these new regulations and other production pressures. Federal government support is a welcome step forward in the control of a major infective disease in Australia, and comes as a substantial relief to the rural community and meat processors. In addition, it keeps faith with the considerable efforts by state health department immunisation teams and medical practitioners to extend the use of the vaccine from abattoirs to the at-risk rural community during the government-subsidised National Q Fever Management Program, 2001–2003/2004 (http://www.immunise.health.gov.au/internet/immunise/publishing.nsf/Content/q-fever-man). Attempts to control Q fever by vaccination have a long history.2 After the discovery of clinical Q fever and isolation of the causative organism by Edward Derrick in Queensland in the 1930s, and the subsequent identification of the isolates (an obligate intracellular bacterium) by Macfarlane Burnet, the disease emerged as an important “campaign” infection (Balkan grippe) for armies in the Mediterranean arena during World War II. At the time, various vaccine formulations were prepared from the coxiella grown abundantly in chick embryo yolk sacs, as devised by H R Cox at the National Institutes of Health/National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratory, Montana, USA. Suspensions of infected yolk sac were inactivated with formalin and ether (eg, by Smadel and colleagues).2 These were protective in animals and in human volunteer and challenge trials. But use in humans produced unpredictable, severe local reactions. Derrick expressed a common view of these early Q fever vaccines in his 1964 Elkington Oration: “What of the future; there is an effective vaccine but it produces unacceptable reactions”.3 His assessment is still repeated uncritically in the medical literature. The experience in Australia from 1980 to 2005 with the present generation of whole-cell vaccines (eg, Q-Vax [CSL Limited]) and a different vaccination protocol has been quite the reverse. The contemporary whole-cell, formalin-inactivated Q fever vaccine has also sometimes been dismissed as “old-fashioned”— ignoring a protective efficacy of over 95%. In fact, the formulation is appropriate for the complex immunopathology of acute Q fever. Insight into the critical components for an improved whole-cell vaccine started in Cambridge in the 1950s with Stoker and Fiset’s4 discovery of the antigenic phase variation of Coxiella burnetii. Concurrent studies, also in Cambridge, by Abinanti and Marmion5 showed that antibody to the Phase I antigen (ie, the lipopolysaccharide of coxiella cells with a complete set of sugar residues in its O-chains) was protective in a mouse spleen model of Q fever infection. On the other hand, protection was not conferred by antibody to Phase II antigens (ie, from coxiella with a full complement of proteins, but with genetically driven or other variations in the level of synthesis of complete lipopolysaccharide O-chains — recent research reports6,7 give a more detailed explanation of the chemistry of phase variation). Subsequently, Ormsbee et al8 at Rocky Mountain Laboratory extended these observations to show that a formalin-inactivated vaccine made from coxiella predominantly in the Phase I antigenic state was significantly more protective in a guinea pig model of Q fever on a weight-for-weight basis than one made from cells predominantly in Phase II. The latter preparation, and indeed the earlier vaccines developed by Smadel, probably owed their partial protective properties to residual Phase I cells in a population of Phase II variants. The importance of Phase 1 lipopolysaccharide as a protective immunogen is supported by the finding that a Phase I Q fever vaccine loses its protective efficacy in mice when treated with potassium periodate to ablate the sugar residues in the lipopolysaccharide (unpublished data). The major host cells for C. burnetii in animals and humans are in the monocyte–macrophage lineage. The interactions of coxiella with this key regulatory cell series for the cellular immune system underlie both the immunopathogenesis of Q fever and the prophylaxis afforded by the vaccine. The coxiella proteins (as peptides) stimulate T-lymphocyte immunity and memory, with the generation of interferon-γ and other cytokines that control intracellular replication of coxiella.2 On the other hand, interactions of coxiella and monocyte–macrophage cells produce mediators that down-regulate the cellular immune system and the formation of interferon-γ by T lymphocytes.9,10 A possible explanation for the central requirement of the Phase I determinant in a vaccine is that antibody to it blocks interaction of coxiella and the monocyte–macrophage cells. Consequently, down-regulation of the cellular immune system does not occur and coxiella growth is restricted. A contributory component for vaccine efficacy may be the slow biodegradability of the small-cell variant of coxiella. This displays both Phase I lipopolysaccharide and protein antigens, thus providing continuing antigenic stimulation and protection. An important step in the development of the current protocol for vaccination was the finding by Lackman and colleagues2 at Rocky Mountain Laboratory that adverse reactions to whole-cell vaccine could be minimised by intradermal skin testing of potential vaccinees with a dilute vaccine to detect prior cellular immune sensitisation. In the early 1980s, 50 years after Derrick’s discovery — and probably after some 40 000 overt cases of Q fever — Dick Ormsbee and I asked CSL Limited to make Ormsbee’s highly purified version2 of Q fever vaccine with its negligible residual yolk protein. At the time we knew that Hornick, Fiset and colleagues,2 under the auspices of the Commission on Rickettsial Diseases (US Armed Forces), had vaccinated volunteers with whole-cell vaccine and challenged them with aerosols of living C. burnetii. Even small doses (1–10 μg) of vaccine were protective. Open clinical trials of the Ormsbee-type vaccine (Q-Vax) (produced by CSL) at a dose of 30 μg as a subcutaneous injection were performed in workers at four abattoirs in South Australia in the 1980s.2 These established the vaccine’s safety in an industrial environment in which prior clinical or subclinical infection and immune sensitisation were common. As in the US volunteer trials, the vaccine was protective. A formal “blind” comparison of Q-Vax and influenza virus vaccine performed at three Queensland abattoirs also showed complete protection.2 Box 1 shows the practical value of vaccine prophylaxis in a large abattoir group in Queensland, 1992–2005. Occupationally acquired, laboratory-proven Q fever is compensable. Compensation claims — a significant expense for the industry — declined steadily after the vaccination program started. Box 2 shows the number of Q fever cases notified to the National Notifiable Diseases Surveillance System across Australia, 1991–2006. The yearly totals include Q fever cases both in and outside abattoirs. Abattoirs across the country gradually took up vaccination from 1993–1994, greatly aided by CSL’s vaccine consultants. During the period 1994–2000, although the number of Q fever notifications stabilised at around 500–600 per year, probably reflecting fewer cases in abattoirs, an unambiguous downward trend in Q fever notifications for the country as a whole did not occur. This is not surprising, as it has been apparent since the 1930s that only a variable proportion of Q fever cases occurs in abattoirs (eg, 68% of Derrick’s series of 273 cases11). During the National Q Fever Management Program, state immunisation teams worked intensely to vaccinate abattoir workers, and rural and other at-risk groups in the population. Evaluation continues, but Box 2 shows an encouraging and significant decline in case numbers from 2003 to 2006. What of the future? Further refinement of existing vaccine protocols is needed as problems surface from wider use. Efforts to produce less reactogenic vaccines for use without pretesting are summarised in Box 3.2 Balanced against the continuing and substantial Q fever problem in Australia, the current whole-cell vaccine and protocol are effective, they have been tested in over 150 000 subjects, and prophylaxis for this disease is available now. 1 Control of abattoir-associated Q fever in a major Queensland abattoir complex Claims per annum for compensation for clinically and laboratory-proven, occupationally acquired Q fever. (Data supplied by and reproduced with permission of Australian Meat Holdings, Queensland.) 2 Vaccination and changing trends in the numbers of notified cases of Q fever across Australia, 1991–2006 Means (SEs) for 1991–2002 and 2003–2006; P = 0.01 for comparison of means. (Yearly totals for Q fever notifications and the basic curve are from the National Notifiable Diseases Surveillance System.) 3 Efforts to produce less reactogenic, alternative vaccines without the need for pretesting Extracts of coxiella containing lipopolysaccharides and protein (eg, chemovaccine)2 or delipidated coxiella cell residues2 are protective in animals. Chemovaccine has been used in Eastern Europe in laboratory workers and some industrial groups. It is protective, but about as reactogenic as whole-cell vaccine. To establish efficacy, duration of protection and reactogenicity (severe adverse incidents are rare and idiosyncratic), comparative trials are needed of these vaccines versus whole-cell vaccine in larger numbers of subjects. There is also active research into simpler vaccines of coxiella proteins prepared by recombinant DNA methods.12 So far, coxiella proteins alone appear not to be protective,13 although a recombinant fusion protein given with Freund’s complete adjuvant (a potent macrophage activator) protected in a mouse model.14 The quest for a simpler vaccine should continue; whether successful or not, it is yielding valuable insights into the immunobiology of Q fever. But the three-component nature of the existing vaccine and the roles in protection of lipopolysaccharides, macrophages and antibody need to be taken into account.

Barrie Marmion AO, MD, FRCPA, DSc

Despite the emergence of multidrug-resistant strains of hepatitis B virus (HBV) and previous success with combination therapy for other chronic viral infections, we are still using sequential monotherapy for chronic HBV infection. Antiviral-resistant HBV can result in major life-threatening complications. We now have complementary drugs, such as lamivudine and adefovir dipivoxil, with fundamentally different structures and associated with different signature resistance mutations, with adefovir dipivoxil showing antiviral activity against most lamivudine-resistant strains. Studies of combination therapy to date have used traditional endpoints — short-term reduction of HBV DNA levels and HBeAg seroconversion — rather than evolution of resistance. There is now an emerging body of data suggesting that combination therapy can decrease antiviral resistance in HBV infection, the endpoint likely to be of greatest long-term importance, and, rather than adding or replacing an antiviral agent after resistance develops, it is likely to be more effective in treatment-naïve patients.

Joseph J Sasadeusz FRCPC, FRACP, PhD · Stephen L Locarnini PhD, FRC(Path) · Graeme Macdonald FRACP, PhD

To the Editor: Humans may serve as intermediate hosts in hydatid disease, a parasitic infection caused by the tapeworm Echinococcus granulosus. They are infected through contact with infected dogs or by ingestion of tapeworm eggs in contaminated food, water, or soil.1 The larvae form cysts in body organs. Although the liver is the most common site, lung cysts are seen in up to 30% of cases of hydatid disease. Lung cysts are generally asymptomatic, but symptoms occur if the cysts rupture.2 Here, we describe an adolescent girl with a lung cyst that ruptured across the thoracic cage into the subcutaneous fascia, presenting as a breast swelling. A 14-year-old girl had had left-sided pleuritic chest pain, a high-grade fever, and marked swelling of the left breast for 10 days, which did not respond to antibiotics (oral amoxycillin and parenteral amikacin). Clinical examination revealed a slender, febrile and tachy-pnoeic patient with a tender swelling of the left mammary region. The swelling had a tense cystic feel, and transmitted impulses were felt when she coughed. A diffuse pleural rub was heard anteriorly, with reduced air entry. Investigations revealed a neutrophilic leukocytosis of 12.7 × 109/L. Chest x-ray showed diffuse opacification of the left hemithorax, and a computed tomography scan revealed a cystic, low-attenuation lesion in the left hemithorax extending into the submammary region (Figure A). On anterolateral thoracotomy, an infected ruptured cyst was seen in the left upper lobe of the lung, with degenerated membranes and pus extending across the chest wall into the submammary space. The cyst was removed, capitonnage of the residual cavity was performed, and pus and laminated membranes were removed from the submammary space. Small communications seen between the pus cavity and the bronchi were closed. After the operation, parenteral anti-biotics (vancomycin and amikacin) were administered for 10 days and albendazole for 4 weeks. Casoni’s skin test was positive and antihydatid antibodies were detected in serum. Surgically obtained pus revealed non-viable scolices of E. granulosus (many degenerated), and the histopathology of the surgical specimen was consistent with hydatid membrane (Figure B). Pulmonary hydatid cysts can rupture; however, rupture into the pleural cavity is rare.1-3 Although spontaneous rupture of a cyst into the pleural cavity, or rupture after trauma, has been reported,4,5 a rupture across the pleural cavity into the submammary fascial tissues has, to our knowledge, not been reported previously. A. Computed tomography scan showing a cystic lesion in the left hemithorax, extending into the submammary region (arrow). B. Degenerated hydatid cyst membrane (original magnification × 200).

Parvaiz A Koul · Abdul Wahid · Ghulam N Lone · Tariq A Bhat

Vaccination response has been impressive, but the hypermutable meningococcus is likely to continue to challenge us In the past 100 years there have many dramatic fluctuations in the incidence of meningococcal disease in Australia, as Patel describes in this issue of the Journal.1 Rising socioeconomic status with reduced household crowding has probably been the major factor in curbing the overall incidence of the disease in recent decades,1 but the introduction in early 2003 of a routine vaccination against serogroup C for all infants (and a catch-up campaign for those aged under 20 years) has also had an undeniably impressive impact. Worldwide, surges in the incidence of meningococcal disease due to serogroups A, B, C, W135 and Y have each been associated with the advent of a new strain to which the community largely lacks immunity. Furthermore, new strains are often associated with a higher case-fatality rate and a shift to the right in age incidence, with the disease especially affecting older teenagers. More commonly, these young people do not have the disease but are colonised by the organism and may become “superspreaders” of infection.2,3 The epidemiological signal of rising serogroup C meningococcal disease incidence was detected in the United Kingdom in 1994. A triumvirate of government, industry and academia combined to produce a “win, win, win” situation — an effective and safe vaccine being researched, developed, mass produced and introduced within a mere 5 years.4 As a consequence of vaccination, serogroup C disease is now controlled in a number of developed countries. However, the incidence of serogroup C meningococcal disease in teenagers had already peaked in half the regions of the UK and was declining before the vaccine was introduced in 1999. Similarly, in New South Wales, disease incidence was falling before the vaccine was introduced (perhaps due to naturally acquired herd immunity5), whereas, in Victoria, vaccination led to a rapid fall in incidence. Western Australia and South Australia had not seen the same surge of serogroup C disease as in the eastern states.6,7 However, it should be emphasised that, in the 3 years after the vaccine was introduced, there was a decrease in notification rates in all states and territories except WA, where notification rates remained low. As in the UK, a catch-up campaign was undertaken in Australia for those younger than 20 years of age. Unlike the UK, where routine vaccination was given as a three-dose course in the first 6 months of life, Australia was able to follow a simpler, more cost-effective approach and offer a single dose at 12 months of age. This was because almost all serogroup C disease was seen in older children, teenagers and young adults, and also because the vaccine is more immunogenic in older infants and children. Australia’s approach has proved successful. A similar outcome has been achieved in the Netherlands, where a single dose is administered routinely at 14 months of age.8 In 2005, only 50 laboratory-confirmed serogroup C cases were notified in Australia. This is a greater than 75% reduction from the 213 cases in 2002. There is also evidence that, in the absence of vaccination, disease incidence may fall as naturally acquired immunity rises5 but the impact is not as rapid; herd immunity may also be induced by vaccination but its longevity is uncertain.9 Given the extraordinary velocity of the vaccine’s development in the UK, inevitably some issues received attention later than desirable. One was cost-effectiveness — data on this were published well after vaccine introduction.10 There was interest in both the UK and Australia in the possible use of the cheaper polysaccharide vaccine, as it is effective in the age ranges mostly affected by serogroup C disease and may also be more cost-effective.11 This approach was tried in Spain, but waning immunity after several years led to a follow-up conjugate C vaccine campaign. Given that this disease can progress with frightening rapidity and has a high case-fatality rate, it receives, arguably, inordinate media attention. The political pressure and impetus to implement a vaccination program that this publicity generates is often lacking for diseases with a lesser public profile. When meningococcal C vaccine was introduced in Australia, there was debate about its merits in relation to, for example, the pneumococcal conjugate vaccine, which is now also part of the routine schedule. Australia was arguably the first country in the world to fund universal immunisation against Haemophilus influenzae type b, meningococcus C, and pneumococcus in early childhood. Long-term follow-up will be required to assess the ultimate success of the meningococcal C vaccine program and determine whether booster doses of vaccine might be required or whether serogroup replacement develops. The problem of serogroup B disease remains. New Zealand has recently completed a large and expensive public health intervention to vaccinate its young people against a particular serogroup B strain that, beginning 15 years ago, caused a major upsurge in incidence. This vaccine would cover only a small proportion of serogroup B cases in Australia,6,7 so a different product will be required here, and studies are underway in several Australian centres to assess candidate serogroup B vaccines. Without a vaccine, it is questionable whether behaviour modification would mitigate risk. Patel claims that “the societal determinants of the current hypersporadic disease pattern are unknown”.1 This is at odds with Australian and overseas data clearly showing that crowded environments, including university colleges and nightclubs, and risk-taking behaviour (eg, smoking and multiple deep-kissing contacts) are important risk factors12 and may be modifiable. Despite the recent unravelling of sequence data for the entire genomes of representative strains of meningococcal serogroups A, B and C, the hypermutable meningococcus will likely continue as an “accidental tourist” causing havoc in a small proportion of vulnerable hosts1 and go on challenging public health control measures throughout the 21st century.

Robert Booy MD, FRACP, FRCPCH · Jane Jelfs PhD · Haitham El Bashir FRCPCH, MRCP · Michael D Nissen FRACP, FRCPA

Trends in meningococcal disease (MD) over the 20th century in Australia, as in other industrialised countries, have been characterised by epidemics during the two World Wars, a transient rise in incidence in the 1950s followed by endemic disease, and in the 1980s the emergence of a sustained hypersporadic phase. Epidemics occur at times of social upheaval and among marginalised populations, and resolve when living conditions improve. Periodic serogroup A epidemics have been replaced since the 1950s by endemic disease caused mainly by serogroups B and C meningococci. The current hypersporadic plateau in Australia, as in other industrialised countries, is associated with the intercontinental spread of hypervirulent clones of meningococci. The conjugate serogroup C vaccine has reduced the incidence of MD and carriage rates of serogroup C meningococci. However, the vaccine is expensive and its long-term impact on the emergence of non-vaccine strains and on nasopharyngeal microecology is unknown. A rising incidence of MD should not be viewed as the action of a virulent microbe exploiting a vulnerable population, but as the emergence of an “accidental pathogen” from an evolving host–microbial ecology. While it is essential to monitor the impact of vaccines on this ecology, we must find ways that can optimise our coexistence with microbes.

Mahomed S Patel MB BCh, FRACP, FAFPHM

Over the past 10 years, the management of HIV infection has been transformed by an increased number of effective antiretrovirals (ARVs), with more convenient dosing and improved tolerability. Optimal management of HIV infection includes at least three effective ARVs; from at least two different drug classes. Current strategies and drugs can effectively control HIV and significantly reduce morbidity and mortality. However, no cure is yet possible. Appropriate use of ARVs leads to suppression of virological replication (to below the limit of detection using commercial assays to measure HIV in plasma) and an increase in CD4+ T cells with few adverse effects. Greater than 95% adherence to drug therapy is required for effective viral suppression and immunological improvement. Monotherapy, two-drug combinations, sequential ARVs, drug “cycling”, and treatment interruptions are ineffective management strategies and lead to earlier disease progression and emergence of drug resistance. Drug–drug interactions are common and caution is required when prescribing ARVs that inhibit or induce the cytochrome P450 pathway.

Luke F Chen MB BS(Hons) · Jennifer Hoy MB BS, FRACP · Sharon R Lewin MB BS(Hons), PhD, FRACP

To the Editor: We read with interest the “Diagnostic Dilemma” by Peter et al.1 The case raises interesting management issues. The first is initiation of antibiotics. Despite 1 week of fever, rigors, haematuria and loin pain, we are informed that the patient was in no distress at initial assessment. In this situation there is, despite the anxieties of resident staff, no urgent need to administer antibiotics; hospitals are controlled, monitored environments in which observation, review and investigation can be undertaken, within reason, if a diagnosis is not immediately made. The second issue is antibiotic selection. The provisional diagnosis was a urinary tract infection, and ceftriaxone and gentamicin were administered. The justification for the use of two agents with a similar spectrum of antimicrobial activity is not given.2 Likewise, no justification is given for the use of a potent nephrotoxin in the presence of moderately severe acute renal failure. Flucloxacillin was added “to broaden the gram-positive antibiotic cover”. It is not apparent why staphylococcal cover was sought at this stage. All cultures (blood, urine and pleural fluid) remained negative. At Day 14, ceftriaxone and gentamicin were changed to ticarcillin/clavulanic acid and ciprofloxacin “because of persistent fever and rising [white cell count]”; this decision in the absence of positive cultures is not explained. The patient’s renal function deteriorated further and he became profoundly acidotic. In fact, the patient’s renal function had performed heroically, given administration of gentamicin for 2 weeks in the presence of acute renal failure at admission. In the intensive care unit, flucloxacillin was replaced with vancomycin; the rationale is not explained. This case illustrates important points regarding antibiotic use. Despite significant renal impairment at admission, the patient was administered a 2-week course of a nephrotoxic antibiotic, which contributed to renal collapse. This situation would have been terminal if not for supportive intensive care. The treating team appears to have managed the patient as if sepsis were a given, and yet all cultures remained negative. This illustrates a basic but crucial teaching point — fevers, chills, rigors, raised inflammatory markers and neutrophilia do not necessarily equate with sepsis. If this experience reflects routine practice elsewhere (and it is our experience that it does), is it any wonder that we have reached an era in which we now encounter organisms so resistant that they are essentially untreatable?3

Mark A Boyd · Stephen Hedger

In reply: Boyd and Hedger have raised concerns regarding the initiation and choice of antibiotics in our recent case report.1 Several aspects of this correspondence need to be addressed. The primary focus of the article was to highlight an important and probably underrecognised cause of unexplained metabolic acidosis, and discussion regarding antibiotic choice was not within the scope of the article. Further, the patient’s management before admission to the intensive care unit was by a different treating team. Subsequent case-note review did not reveal reasons for initiation or choice of antibiotics other than described in our article, although it was evident that gentamicin doses were adjusted based on drug levels. We agree that a less nephrotoxic agent could have been chosen and that the profligate use of antibiotics in the absence of strong evidence of infection could have been avoided. The excessive use of antibiotics in the current medical milieu may stem from a physician’s lack of confidence, or even legal ramifications of “watching and waiting” in the setting of “fevers, chills, rigors, raised inflammatory markers and neutrophilia”, as encountered in our patient.

John V Peter · Natasha Rogers · Sandra L Peake

Results of studies on the use of antibiotics, alone or in combination with surgery, are encouraging Although Buruli or Bairnsdale ulcer (BU) was described in Uganda, Africa, in 1897, the causative organism, Mycobacterium ulcerans, was only identified in 1948, in Australia.1 Today, the disease has been reported in over 30 countries, mainly in tropical and subtropical regions of Africa, Latin America, Asia and the western Pacific.2 BU is poorly recognised within the medical community, and there is gross underreporting of cases. Australia is the only developed country that has major foci of infection, and BU is now a notifiable disease in the state of Victoria. Over the past decade, the World Health Organization has played a central role in quantifying the problem and bringing together scientists, health experts and funding organisations to increase understanding of the disease, improve management and broaden the delivery of care to patients. There are some differences in BU as it is seen in Australia compared with Africa. Small papular lesions are often seen in Australian cases, and this may not be entirely explained by patients presenting earlier — Australian strains of M. ulcerans produce a slightly different form of the toxin mycolactone.3 Outbreaks of BU in Australia have tended to affect small towns, and patients are usually adults, including the elderly. In Africa, endemic areas are poor rural farming communities, and the average age of affected patients is 5–15 years.4 Although the mode of transmission of infection is still unknown, M. ulcerans has been found in environmental water and water insects, and the epidemiology in both Africa and Australia suggests that people become infected through contact with a contaminated environment rather than with infected people. Much recent research has focused on the role of mycolactone in pathogenesis, and it is clear from animal studies that most of the tissue destruction observed in human lesions is caused by diffusion of this highly toxic macrolide molecule from clusters of M. ulcerans organisms replicating in subcutaneous fatty tissue. This raises the possibility that killing the organism with antibiotics, or even suppressing its ability to produce toxin, may be adequate management. Traditionally, BU is managed by surgical excision of the lesion followed by primary closure or skin grafting. Until recently, antibiotics were thought to have little role in management, despite the fact that M. ulcerans is sensitive to a number of drugs, including rifampicin, aminoglycosides, macrolides and quinolones, in vitro.4 Studies have shown that a combination of rifampicin and an aminoglycoside given to mice with footpad or tail lesions both healed the lesions and prevented recurrences. The combination of rifampicin and moxifloxacin is also effective,5 as is rifampicin alone. However anti-biotic-resistant mutant strains of M. ulcerans can emerge when single-drug treatment is used.6 Findings in animals provide no guarantee of success in humans, but it has now been shown that a combination of rifampicin and streptomycin for a minimum of 4 weeks kills M. ulcerans in early human lesions,7 and longitudinal studies of this combination of antibiotics in all forms of the disease for 8 weeks in Benin, in western Africa, showed that 50% of lesions, including ulcers, healed without requiring surgery.8 Although these results are very encouraging and have led to many physicians in African countries where BU is endemic using antibiotics without recourse to surgery, there have been no controlled trials to validate the treatment. Equally, there are no controlled data on the use of antibiotics together with surgery. The rate of recurrence after surgery is dependent on the surgeon’s ability to guess the extent of infection from the appearance of the lesion, and polymerase chain reaction (PCR) testing of excised tissue has shown that infection extends well beyond the visible margins of disease.9 In this issue of the Journal, O’Brien and colleagues report their experience of managing BU with surgery, antibiotics or a combination of the two.10 The main findings from this restrospective, purely observational study were that antibiotics appeared to reduce the recurrence rate when M. ulcerans was detected in the margin of the excised lesion and when the lesion was large (meaning that skin grafting was needed). The choice of antibiotics was not planned in advance, and depended on the preference of individual clinicians, but rifampicin was included in the regimen for most patients. Interestingly, the recurrence rate in this study was 10% after antibiotic treatment for up to 3 months in patients who had all had their lesions surgically excised, while the recurrence rate after therapy with rifampicin and streptomycin for 2 months in 208 patients in Benin was less than 2% with or without surgery.8 The Australians did not use intramuscular streptomycin in their older group of patients, and found amikacin poorly tolerated. We do not know if their favoured combination of ciprofloxacin with rifampicin adds any bacterial killing benefit, or whether this combination is sufficient to prevent resistance emerging. In the context of a disease that is mainly a problem for children in rural parts of humid tropical Africa, it is no surprise that the approach to management is different in south-eastern Australia where surgery is easily accessible. There is no doubt that more children in Africa are receiving treatment and at an earlier stage of disease now that physicians are offering antibiotic therapy. The opportunity to have lesions excised is available to relatively few of these patients, and they typically present late with large ulcers, both for economic reasons (treatment has a major impact on a family’s finances) and because they fear surgery. Treating large numbers of patients in Benin and Ghana has shown that most lesions become culture-negative after treatment with rifampicin and streptomycin for 8 weeks, and they go on to heal during or after that time.8 The combination of two orally administered antibiotics with powerful bactericidal activity is the therapeutic goal at present, and surgical grafting should only be necessary to speed the healing of ulcers. More work is needed to develop an ideal treatment strategy, in both developing countries and more sophisticated medical settings. The suggested guidelines for diagnosis, treatment and control of M. ulcerans infection in Victoria in this issue of the Journal11 mark a significant step in developing standardised protocols for local use. Although individual doctors in Australia see relatively few cases, if a standard management protocol is followed, considerable experience will be amassed, which may guide future research. It would be useful, for example, to establish whether after treatment with rifampicin and moxifloxacin for 2 weeks before surgery, the excised tissue is culture-negative and the recurrence rate lower. Australians have made major contributions to understanding and diagnosing this disease, and another article in the Journal highlights the role of PCR testing,12 originally developed in Melbourne,13 in tracing the source of infection by means of a PCR-based DNA fingerprinting method. Several new pockets of infection have been identified worldwide in recent years, and while the causes of outbreaks remain obscure, PCR has been a key tool in tracing environmental sources of M. ulcerans, as well as in diagnosis, where it is not only the most sensitive method available (> 90%), but also quicker than all except microscopy for acid-fast bacilli (sensitivity < 50%).14 The challenges now are to make this technology accessible to African countries, and to develop simpler diagnostic tools.

Kingsley Asiedu MD, MPH · Mark Wansbrough-Jones MB BS, MSc, FRCP

Objective: To describe the effect of antibiotics on outcomes of treatment for Buruli or Bairnsdale ulcer (BU) in patients on the Bellarine Peninsula in south-eastern Australia.Design: Observational, non-randomised study with data collected prospectively or through medical record review.Patients and setting: All 40 patients with BU managed by staff of Barwon Health’s Geelong Hospital (a public, secondary-level hospital) between 1 January 1998 and 31 December 2004.Main outcome measures: Epidemiology, clinical presentation, diagnosis, treatment and clinical outcomes.Results: There were 59 treatment episodes; 29 involved surgery alone, 26 surgery plus antibiotics, and four antibiotics alone. Of 55 episodes where surgery was performed, minor surgery was required in 22, and major surgery in 33. Failure rates were 28% for surgery alone, and 19% for surgery plus antibiotics. Adjunctive antibiotic therapy was associated with increased treatment success for lesions with positive histological margins (P < 0.01), and lesions requiring major surgery for treatment of a first episode (P < 0.01). The combination of rifampicin and ciprofloxacin resulted in treatment success in eight of eight episodes, and no patients ceased therapy because of side effects with this regimen.Conclusions: Adjunctive antibiotic therapy may increase the effectiveness of BU surgical treatment, and this should be further assessed by larger randomised controlled trials. The combination of rifampicin and ciprofloxacin appears the most promising.

Daniel P O’Brien MB BS, FRACP · Andrew J Hughes MB BS, FRACP · Allen C Cheng MB BS, FRACP, PhD · Margaret J Henry BSc, PhD · Peter Callan MB BS, FRACS · Anthony McDonald MB BS, FRACS · Ian Holten MD, FRACS, FRCS · Mike Birrell MB BS · John M Sowerby MB BS · Paul D R Johnson MB BS, FRACP, PhD · Eugene Athan MB BS, FRACP

Mycobacterium ulcerans is a slow-growing environmental bacterium that causes Buruli ulcer (also known as Bairnsdale ulcer in Victoria and Daintree ulcer in northern Queensland). We describe two patients with laboratory-confirmed Buruli ulcer who were infected either in New South Wales or overseas. A molecular epidemiological investigation demonstrated that, while one case was probably acquired in Papua New Guinea, the other was most likely to have been acquired in southern NSW. To our knowledge, this is the first case of M. ulcerans infection acquired in NSW. Clinical recordsPatient 1A 50-year-old geologist was referred in April 2005 for assessment of chronic cellulitis and ulceration of the right hand, present for 11 weeks (Box 1). An intraoperative swab showed acid-fast bacilli on Ziehl–Neelsen staining. Buruli ulcer (Mycobacterium ulcerans infection) was confirmed by polymerase chain reaction (PCR) testing. Over the next 3 months, the patient received a combination of antibiotic and surgical therapy. At follow-up 1 week after ceasing antibiotic therapy (4 months after initial presentation), the skin graft had healed, and the patient remained well. The patient lived in rural New South Wales but had travelled to the Mornington Peninsula and East Gippsland regions of Victoria 5 years previously. Two weeks before the onset of illness, he had been fishing in the Snowy Mountains. He also made frequent work trips to Papua New Guinea, with seven trips in the 15 months before illness. His most recent trip there lasted 18 days, and he returned to Australia almost 12 weeks before the onset of infection. Variable number tandem repeat (VNTR) typing (Box 2) revealed that the isolate had the same profile as a previously described M. ulcerans strain from PNG, which differed from Victorian strains at loci 8 and 19.1 Similarly, the isolate had a restriction fragment length polymorphism (RFLP) band profile identical to that of the PNG strain, but differing from that of Victorian strains.2 These results suggest that the infection was acquired in PNG, not Australia. The minimum incubation period in this case was therefore 3 months. Patient 2The second patient was a 42-year-old Australian citizen usually resident in Holland. He presented in Melbourne in January 2006 with a skin ulcer over the left ankle (Box 1) which had been present for 5 months. Buruli ulcer had been correctly diagnosed in the Netherlands, and he had been treated with appropriate antibiotics for 6 weeks with no apparent response. The lesion was excised, a skin graft applied, and further antibiotic therapy given for 6 weeks, resulting in complete resolution. PCR testing performed on resection specimens from the ulcer was positive for M. ulcerans. The patient had travelled widely in Africa between 5 and 2 months before the appearance of the skin lesion; 7 months before its appearance, he had spent 2 weeks sea kayaking near Eden on the southern NSW coast. He had not visited Victoria for at least 10 years. M. ulcerans was not able to be cultured, so typing was performed on DNA extracted from the resection specimens. The two VNTR loci that discriminate between African and Victorian strains were examined.1 The estimated PCR product sizes of 420 base pairs (locus 4) and 650 base pairs (locus 8) were consistent with the Victorian profile.1 A second typing method, multilocus sequence typing, revealed that the patient’s strain lacked the C-to-T substitution in the sodA gene characteristic of African isolates.3 These data suggest that the infection was acquired in southern NSW and not Africa. The incubation period in this case was therefore about 7 months. DiscussionMycobacterium ulcerans infection was first described in patients in the Bairnsdale district of Victoria,4 where it was known as Bairnsdale ulcer. Since then, the disease has been recognised in Far North Queensland (known as Daintree ulcer),5 central coastal Queensland6 and the Northern Territory in Australia,7 and in as many as 30 other countries, including PNG and sub-Saharan Africa.8 In the past 15 years, significant clusters of cases have occurred on Phillip Island9 and the Mornington and Bellarine Peninsulas near Melbourne (Box 3). Despite this wide distribution, no cases have been reported previously from NSW, except in patients who were exposed during interstate or overseas travel.10 M. ulcerans is an environmental pathogen, which is transmitted by an unknown mechanismn to humans who enter endemic areas. Our patients had both travelled to several regions of Australia and overseas where Buruli ulcer occurs. Using a combination of conventional epidemiology and molecular typing, we determined the most likely geographic origin of transmission for each patient: PNG for Patient 1 and southern coastal NSW for Patient 2. The latter case represents the first strong evidence for Buruli ulcer having been acquired in NSW. However, there have been cases of Buruli ulcer from Mallacoota (unpublished data), a small town in eastern Victoria adjacent to the NSW border (Box 3). It is not surprising that M. ulcerans exists in coastal environments in southern NSW, just as it does in Victoria. The rarity of cases in NSW compared with Victoria remains unexplained. It is unlikely to result from failure to recognise previous cases in NSW, as the progressive nature of the infection means that most cases are eventually diagnosed. Australian primary care clinicians need to be aware that Buruli ulcer may occur in NSW, to ensure early diagnosis and treatment to minimise disability. 1 Lesions in Patient 1 (top) and Patient 2 (bottom) 2 What is variable number tandem repeat (VNTR) typing? VNTR typing is a DNA fingerprinting method based on polymerase chain reaction (PCR). The technique detects differences in the number of tandem repeat DNA sequences in specific regions of microbial genomes (known as VNTR loci). Strains of Mycobacterium ulcerans from different geographic regions can be reliably distinguished by VNTR typing.1 VNTR typing is usually performed on cultured isolates, but can be performed using DNA extracted directly from patient specimens. 3 Victoria and southern New South Wales showing relevant regions

Caroline J Lavender BA/BSc(Hons) · Sanjaya N Senanayake MAppEpid, FRACP · Janet A M Fyfe BSc(Hons), PhD · John A Buntine FRACS · Maria Globan BSc · Timothy P Stinear BSc(Hons), PhD · John A Hayman MD, FRCPA · Paul D R Johnson MB BS, PhD, FRACP (Infectious Diseases)

Mycobacterium ulcerans causes slowly progressive, destructive skin and soft tissue infections, known as Bairnsdale or Buruli ulcer (BU). Forty-six delegates with experience in the management of BU attended a 1-day conference in Melbourne on 10 February 2006, with the aim of developing a consensus approach to the diagnosis, treatment and control of BU. An initial draft document was extended and improved during a facilitated round table discussion. BU is an environmental infection that occurs in specific locations. The main risk factor for infection is contact with an endemic area. Prompt cleaning of abrasions sustained outdoors, wearing protective clothing, and avoiding mosquito bites may reduce an individual’s risk of infection. BU can be rapidly and accurately diagnosed by polymerase chain reaction testing of ulcer swabs or biopsies. Best outcomes are obtained when the diagnosis is made early. To aid early diagnosis, health authorities should keep local populations informed of new outbreaks. BU is best treated with surgical excision, which, if possible, should include a small rim of healthy tissue. For small lesions this may be all that is required. However, there is a role for antibiotics for more extensive disease, and their use may allow more conservative surgery.

on behalf of the Mycobacterium ulcerans Study Team*

To the Editor: We disagree with the recent recommendation of Graham and colleagues that all medical students should be offered BCG vaccination.1 In countries with a low prevalence of tuberculosis (TB), the side effects from the vaccine and losing the use of a Mantoux test to readily diagnose recent TB infection outweigh any benefits of a vaccine with relatively poor efficacy. The incidence of pulmonary TB in Australia is low (3.3 per 100 000 per year) and only 1.5% of isolates are multidrug-resistant.2,3 Thus, the likely exposure of medical students and doctors in Australia to pulmonary TB (let alone multidrug-resistant TB) will be low. In addition, most hospitalised patients with pulmonary TB would have been suspected of having TB before being sent to hospital, so adequate respiratory precautions should have been in place for most. This makes the risk of transmission to health care workers very small. Information from the Australian immunisation handbook is also very relevant to this debate.4 BCG can be effective, but mainly in preventing disseminated TB in children (> 80% efficacy). In adults, the overall protective efficacy is only about 50%,4 and the sole Australian study showed, at best, a protective efficacy of only 30%.5 The effect of BCG may not persist for more than 10 years but repeat vaccination is not recommended.4 Adverse events occur in about 5% of those vaccinated, with 2.5% being injection site abscesses and 1% lymphadenitis. About 1% of vaccinees may need medical attention as a result of the adverse event. Anaphylactoid reactions can occur, and keloid scarring can also occur (although rarely) at the injection site. The vaccine is “live”, and therefore contraindicated in anyone who might have HIV, other forms of immunosuppression, or generalised skin diseases.4 Graham and colleagues believe the problem of BCG vaccination interfering with the interpretation of Mantoux results can be overcome by using whole blood-based interferon assays, such as QuantiFERON-TB Gold, purportedly unaffected by BCG vaccination.1 However, the data for QuantiFERON-TB Gold need to be treated with some caution because it is a new test and there is no gold standard against which to compare it for diagnosing latent TB. The specificity of interferon assays in diagnosing latent TB has been estimated at 95% or more,6 but this will still result in a poor positive predictive value if the pretest probability of latent TB infection is low — and this is the case for health care workers in Australia. In summary, Australia is far more likely to protect its health care workers from TB through effective hospital infection control measures and migrant screening than through a vaccination program with a mediocre vaccine.

Sanjaya N Senanayake · Peter J Collignon

To the Editor: Graham and colleagues correctly assert that medical students are at increased risk of infection with Mycobacterium tuberculosis in settings where they are treating patient groups with a high prevalence of active pulmonary tuberculosis (TB).1 This is well illustrated by the increasing prevalence of latent TB infection among medical students in their later clinical years in countries where community TB incidence markedly exceeds that of Australia.2 Their case for a standard approach to screening of medical students at course entry has great merit, and their arguments in favour of using an interferon gamma release assay to screen for latent TB infection would bring Australia into line with current international best practice. However, the data presented do not substantiate a policy of offering BCG vaccination to all Australian medical students whose screening test result for latent TB infection, whether by interferon gamma or tuberculin skin testing (TST), is negative. Although BCG offers definite benefits in reducing the risk of life-threatening disseminated disease in children under 2 years of age, it does not offer dependable protection against pulmonary TB in adults.4 Medical students who are vaccinated with BCG may be lulled into a false sense of security, and neglect other more effective infection control measures that would reduce their risk of TB exposure and infection. Although BCG is a relatively safe vaccine, there is a small but well defined risk of local and systemic adverse events.5 We therefore support a standardised approach to screening medical students with TST or, preferably, interferon gamma at course entry and exit. Screening for latent TB infection should be offered whenever merited during the course of study, after exposure to active TB disease in Australia or abroad. The benefits of chemoprophylaxis on conversion outweigh the risks associated with isoniazid use, and the risks associated with BCG may not be acceptable where the risk of TB exposure for many Australian medical students is currently negligible.

David N Durrheim · Michael J Hensley

In reply: The intention of our article was to highlight inconsistent approaches to tuberculosis (TB) prevention in Australian medical schools and stimulate a new informed debate. We therefore welcome the responses from Senanayake and Collignon, and Durrheim and Hensley. Interference with interpretation of tuberculin skin testing (TST) is one argument cited against the use of BCG vaccination for health care workers. While we agree that the new blood-based tests need further evaluation, unlike TST, they are not affected by BCG because they employ TB-specific antigens. The lack of a gold standard for diagnosis of latent TB affects both TST and the blood-based tests. Recent reviews of these new tests have been favourable — including one that states that, compared with TST, these new assays seem to have “better correlation with surrogate measures of exposure to M. tuberculosis” and that “because of their higher specificity they may be helpful in low-prevalence, resource-rich settings where cross-reactivity due to BCG may pose difficulty in BCG interpretation”.1 In fact, this article summarised the specificity of these new tests as between 95% and 100%. Other authors found a specificity of 98.1%.2 We agree that infection control is crucial in preventing nosocomial TB transmission, but every infection control practitioner has seen patients with unrecognised TB admitted to an open ward. One missed patient can mean contact-tracing and testing of dozens of staff. The Melbourne Mantoux study (involving 14 Melbourne hospitals) found that health care work and years of hospital employment were significantly associated with a positive Mantoux result — indicating the risk to Australian health care workers is not “negligible” as Durrheim and Hensley state. Nosocomial outbreaks of TB are well documented in low-prevalence countries.1,3 BCG is by no means a perfect vaccine. However, while BCG efficacy was once thought to only last 10 years, a recent large study suggested that it persists for 50–60 years,4 and there is new evidence that BCG vaccination may prevent some primary infections.5 While the risk of health care-associated tuberculosis in Australia is currently low, it would be unwise to assume this will remain the case, or that doctors will only work in safe environments. What will be the effects of HIV, further immigration from high-risk countries, drug resistance and the increasing use of immunosuppressant medications on the incidence of TB? We stand by the recommendations in our article, although we acknowledge they are controversial. There should, however, be no controversy about the need for a consistent policy concerning TB prevention in our medical schools.

Maryza Graham · Tanya M Howley · Robert J Pierce · Paul D R Johnson