Community-acquired MRSA bacteraemia

To the Editor: Community-acquired methicillin resistance in Staphylococcus aureus was only reported in eastern Australia as recently as 1998.1 We report a case of community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA) causing cellulitis and bacteraemia.

A 30-year-old man presented to the emergency department with a short history of heel pain. There was no history of trauma, diabetes, drug misuse, contact with hospitals or previous antibiotic treatments before the current illness. Examination showed that he had a temperature of 37.7°C and sinus tachycardia of 120 beats per minute. There was extensive cellulitis surrounding a superficial collection of pus over the left heel; this was incised and drained.

Initial investigations showed only neutrophilia. Blood cultures, but no swabs, were taken. Therapy with daily intravenous injections of 1 g ceftriaxone, given at home by an ambulatory care service, was initiated.

The following day, blood cultures showed the presence of gram-positive cocci identified as a Staphylococcus sp., and the treatment was changed to 2 g of cephazolin 12-hourly, intravenously. On the second day Staphylococcus aureus resistant to oxacillin was isolated. There was susceptibility to erythromycin, clindamycin, tetracycline, ciprofloxacin, vancomycin, rifampicin and fusidic acid. Treatment with vancomycin (1 g 12-hourly, by means of a peripherally inserted central catheter) resulted in clinical improvement within 48 hours and was continued for a total of two weeks, followed by oral rifampicin and fusidic acid. A bone scan and echocardiogram showed no significant abnormality. Resolution was complete at six weeks and the patient returned to work.

Methicillin-resistant Staphylococcus aureus (MRSA) is now a common cause of skin and soft tissue infections.2-4 MRSA was not acquired outside hospital until the 1980s, when intravenous drug users from Detroit were reported with MRSA bacteraemia. Such community-acquired strains have now been reported worldwide, including in Australia.5 These strains are usually non-multiresistant MRSA,3 which are highly pyogenic, readily communicable and predominantly cause skin and soft tissue infections. However, CAMRSA endocarditis and a bacteraemic osteomyelitis have been described. We believe this to be the first case of CAMRSA bacteraemia to be reported in Australia.

Community-acquired MRSA strains have become a common cause of community-acquired staphylococcal infection in Australia.2,3 It is now recommended that swabs be routinely taken to cover the possibility of drug-resistant organisms such as MRSA.1-3 The appropriate initial management of suspected or high-risk cases is unclear, but might include treatment with vancomycin or gentamicin before the availability of antibiotic sensitivity test results.