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Clayton L Golledge and Thomas V Riley
Introduce the right kind of bacteria and several pathogens lose their niche in the human host -- that's the rationale behind probiotic therapy. These and some other "natural" therapies are popular with patients and increasingly supported by research results.
MJA 1996; 164: 94
Introduction - Useful bacteria - Other examples of "natural" therapies - References - Authors' details
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Patients too are changing and becoming better informed about their
diseases and possible therapeutic strategies. More and more they are
looking to providers of "alternative" therapies, either as
adjunctive treatment or to replace conventional medical therapy.
There are several non-antibiotic approaches to the treatment and
prevention of infection. Phytomedicines (plant-based remedies in
the form of teas, extracts and oils) are a multimillion dollar
industry worldwide,1 and
many are targeted towards infectious diseases. Some of these
remedies have been, or are being, studied in controlled clinical
trials, although few good data currently exist. Nevertheless, it
behoves the informed practitioner to be aware of some of the
possibilities and the current status of research with these
compounds.
Women suffering recurrences of urinary tract infection have a
urogenital flora depleted of lactobacilli.2,3 Treatment with oestrogen
supplementation can replace the lactobacillus biofilm and reduce
the incidence of urinary tract infection.4 A lack of lactobacilli and
overgrowth of anaerobes is a necessary precondition of bacterial
vaginosis.5 Candida
vaginitis is also associated with a lack of lactobacilli, usually
induced by antimicrobial therapy. Lactobacilli are also
susceptible to spermicidal preparations containing nonoxynol-9,
which explains, at least in part, the increased incidence of
urogenital infections seen in women who use such contraceptives.6
Lactobacilli have been used, with varying degrees of success, to
prevent urinary tract infection in women,7 vulvovaginal candidosis8,9 and bacterial vaginosis.9 Unfortunately, all the studies,
while showing at least some benefit, suffered from either a lack of
adequate controls or low numbers of compliant patients.
Questions still to be answered are how best to deliver lactobacilli
and which species is best to use. Lactobacilli taken orally do not
persist in the gut, so continuous dosing is required.10 Commercial pasteurised yoghurts
contain no useful viable bacteria. Direct high-concentration
intravaginal delivery appears to be the most useful technique in the
prevention of urogenital infections, as indicated by two recent
publications employing vaginal pessaries containing 109 viable cells of Lactobacillus
casei.11,12 Limited
studies suggest that L. acidophilus or L. casei
appear to be equally effective.9,11,12
Diarrhoea associated with Clostridium difficile (CDAD) may
be difficult and expensive to treat, and relapse rates approximate
25% with a variety of different treatment regimens. Oral
Lactobacillus GG has been used with success in the therapy of
relapsing CDAD,13 and
rectal administration of faecal enemas14 or pure cultures of a
non-toxigenic strain of C.difficile15 has also been used in the treatment
of difficult cases.
Lately the results of several clinical trials of the yeast
Saccharomyces boulardii for the treatment of CDAD have been
published. When swallowed, S. boulardii survives gastric
acid, establishes itself in the intestinal tract and multiplies to
high numbers. It is not inhibited by antibiotics and does not affect
the normal flora significantly.16
S. boulardii is effective in preventing CDAD and in
treating various types of infectious diarrhoea.17,18 It may be that S. boulardii
therapy becomes an essential component of primary therapy for
CDAD, particularly given concern about the use of oral vancomycin and
the emergence of vancomycin-resistant enterococci.
"Natural" therapies are viewed favourably by many patients, chiefly
because they believe, often correctly, that they are associated with
fewer detrimental effects than most antibiotics. Unfortunately,
the medical profession has been slow to embrace natural therapies and
good scientific data are lacking. For the few situations discussed
here there may be an important role for these agents and, while the
results of further trials are awaited, we think that judicious use of
adjunctive or replacement natural therapy is easy to justify.
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©MJA 1997
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© 1997 Medical Journal of Australia.
Introduction
Antimicrobial therapy is at the crossroads. Drug development is
palpably slowing and antimicrobial resistance is inexorably
increasing. The early promise of exciting breakthroughs in the field
of immunotherapy of infectious diseases has not been fulfilled,
although progress continues to be made.
Useful bacteria
There is no doubt that the normal intestinal flora protects the host
against many diseases.2 Our
intestinal flora may be perturbed in disease and by diet and
antibacterial substances, both prescribed and present in
foodstuffs. "Probiotic" therapy uses a live microbial supplement to
beneficially affect the host.2
Three genera that have been shown to be important components of
the intestinal flora and probiotic therapies are lactobacilli,
streptococci and bifidobacteria. Most work has been done with
lactobacilli in the gut and in the urogenital tract of women.
Other examples of "natural" therapies
Garlic was once used by millions to ward off vampires and was first
prescribed in 3000 BC by the Sumerians.1 The antibacterial properties of
garlic have been known for many years and can be attributed to the
presence of allin which, when converted to allicin in vivo, is
active against many bacteria.1
Traditional Chinese medicine has provided us with
artesunate, a qinghaosu derivative, and a potentially useful agent
for the treatment of malaria.19
Many traditional Australian Aboriginal remedies have yet to
be investigated, but tea-tree oil is currently enjoying a
renaissance in popularity as a topical antimicrobial agent. Recent
studies have shown it to be effective in vitro against a
variety of organisms, including methicillin-resistant
Staphylococcus aureus,20
and several clinical trials are now under way. Cranberry juice
has been a folk remedy for urinary tract infection since early this
century and is widely used throughout the United States. Studies
in vitro have shown that cranberry juice is able to diminish the
binding of Escherichia coli to eukaryotic cells. A recent
prospective, randomised, placebo-controlled trial21 among elderly women with
asymptomatic bacteriuria showed a 50% reduction in the incidence of
both asymptomatic and symptomatic bacteriuria. Cranberry juice is
now being marketed in Australia and is also available in capsule form.
References
Authors' details
Department of Microbiology and Infectious Diseases, Western
Australian Centre for Pathology and Medical Research, Perth, WA.
Clayton L Golledge, FRCPA, FACTM, Consultant in Clinical
Microbiology and Infectious Diseases.
Thomas V Riley, PhD,
FASM, Associate Professor; also Principal Research Scientist,
Department of Microbiology, The University of Western Australia.
No reprints will be available. Correspondence: Dr C L Golledge,
Department of Microbiology and Infectious Diseases, The Western
Australian Centre for Pathology and Medical Research, Queen
Elizabeth II Medical Centre, Nedlands, WA 6009.
E-mail:
triley AT cyllene.uwa.edu.au