Could Bacterial Vaginosis Be Due to the Competitive Suppression of Lactobacilli by Aerobic Microorganisms?

Fredricsson, B.; Englund, Katarina; Nord, Carl Erik; Weintraub, Leon

doi:10.1159/000294862

Cited by 5 publications

(2 citation statements)

References 9 publications

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“…These GI and vaginal commensalisms confer significant health benefits upon the host organism through a barrier effect by preventing access to these regions by transient pathogens (9,23). Indeed, a delicate quantitative balance of vaginal yeasts is maintained and limited by Lactobacillus species, presumably through peroxide production (24,33). To this end, live microbes are being marketed and actively consumed as probiotic supplements to alleviate or prevent certain GI tract disorders and vaginal yeast and urinary tract infections (23,33).…”

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Bile-Mediated Aminoglycoside Sensitivity in Lactobacillus Species Likely Results from Increased Membrane Permeability Attributable to Cholic Acid

Elkins

Mullis

2004

Appl Environ Microbiol

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Few studies have been conducted on antimicrobial resistance in lactobacilli, presumably because of their nonpathogenic nature as anaerobic commensals. We assessed resistance in 43 type strains and isolates representing 14 species by using agar disk diffusion and MIC analysis in MRS medium. Most noteworthy were two general phenotypes displayed by nearly every strain tested: (i) they were more susceptible (up to 256-fold in some cases) to the deconjugated bile acid cholic acid than to the conjugate taurocholic or taurodeoxycholic acid, and (ii) they became susceptible to aminoglycosides when assayed on agar medium containing 0.5% fractionated bovine bile (ox gall). Two-dimensional MIC analyses of one representative strain, Lactobacillus plantarum WCFS1, at increasing concentrations of ox gall (0 to 30.3 mg/ml) displayed corresponding decreases in resistance to all of the aminoglycosides tested and ethidium bromide. This effect was clinically relevant, with the gentamicin MIC decreasing from >1,000 to 4 g/ml in just 3.8 mg of ox gall per ml. In uptake studies at pH 6.5, [G-3 H]gentamicin accumulation increased over control levels when cells of this strain were exposed to bile acids or reserpine but not when they were exposed to carbonyl cyanide m-chlorophenylhydrazone. The effect was dramatic, particularly with cholic acid, increasing up to 18-fold, whereas only modest increases, 3-and 5-fold, could be achieved with taurocholic acid and ox gall, respectively. Since L. plantarum, particularly strain WCFS1, is known to encode bile salt hydrolase (deconjugation) activity, our data indicate that mainly cholic acid, but not taurocholic acid, effectively permeabilizes the membrane to aminoglycosides. However, at pHs approaching neutral conditions in the intestinal lumen, aminoglycoside resistance due to membrane impermeability may be complemented by a potential efflux mechanism.

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confidence: 99%

Bile-Mediated Aminoglycoside Sensitivity in Lactobacillus Species Likely Results from Increased Membrane Permeability Attributable to Cholic Acid

Elkins

Mullis

2004

Appl Environ Microbiol

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“…3A ). Despite there being few reports of two of the lineages ( L. reuteri and L. plantarum ) in the vagina ( 23 , 24 ), the first 7 lineages were previously often reported as occurring in the human vagina and were widely thought to be associated with the vaginal microbiota ( 25 , 26 ). In the study, we identified an additional 2,200%, 33%, 20%, 6%, 643%, 19%, and 50% novel sequence/reference sequence in these 7 lineages, which may be considered new reference sequences for the present database ( Fig.…”

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confidence: 99%