The role of acidification in the inhibition of <it>Neisseria gonorrhoeae </it>by vaginal lactobacilli during anaerobic growth
<p>Abstract</p> <p>Background</p> <p>Vaginal lactobacilli protect the female genital tract by producing lactic acid, bacteriocins, hydrogen peroxide or a local immune response. In bacterial vaginosis, normal lactobacilli are replaced by an anaerobic flora and this may i...
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BMC,
2011-02-01T00:00:00Z.
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| Summary: | <p>Abstract</p> <p>Background</p> <p>Vaginal lactobacilli protect the female genital tract by producing lactic acid, bacteriocins, hydrogen peroxide or a local immune response. In bacterial vaginosis, normal lactobacilli are replaced by an anaerobic flora and this may increase susceptibility to <it>Neisseria gonorrhoeae</it>, a facultative anaerobe. Bacterial interference between vaginal lactobacilli and <it>N. gonorrhoeae </it>has not been studied in liquid medium under anaerobic conditions. By co-cultivating <it>N. gonorrhoeae </it>in the presence of lactobacilli we sought to identify the relative contributions of acidification and hydrogen peroxide production to any growth inhibition of <it>N. gonorrhoeae</it>.</p> <p>Methods</p> <p>Three strains of <it>N. gonorrhoeae </it>distinguishable by auxotyping were grown in the presence of high concentrations (10<sup>7</sup>-10<sup>8 </sup>cfu/mL) of three vaginal lactobacilli (<it>L. crispatus</it>, <it>L. gasseri </it>and <it>L. jensenii</it>) in an anerobic liquid medium with and without 2-(<it>N</it>-morpholino)-ethanesulfonic (MES) buffer. <it>Fusobacterium nucleatum </it>was used as an indicator of anaerobiosis. Bacterial counts were performed at 15, 20 and 25 h; at 25 h pH and hydrogen peroxide concentrations were measured.</p> <p>Results</p> <p>Growth of <it>F. nucleatum </it>to >10<sup>8 </sup>cfu/mL at 25 h confirmed anaerobiosis. All bacteria grew in the anaerobic liquid medium and the addition of MES buffer had negligible effect on growth. <it>L. crispatus </it>and <it>L. gasseri </it>produced significant acidification and a corresponding reduction in growth of <it>N. gonorrhoeae</it>. This inhibition was abrogated by the addition of MES. <it>L. jensenii </it>produced less acidification and did not inhibit <it>N. gonorrhoeae</it>. Hydrogen peroxide was not detected in any experiment.</p> <p>Conclusions</p> <p>During anaerobic growth, inhibition of <it>N. gonorrhoeae </it>by the vaginal lactobacilli tested was primarily due to acidification and abrogated by the presence of a buffer. There was no evidence of a specific mechanism of inhibition other than acid production under these conditions and, in particular, hydrogen peroxide was not produced. The acidification potential of vaginal lactobacilli under anaerobic conditions may be their most important characteristic conferring protection against <it>N. gonorrhoeae </it>infection.</p> |
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| Item Description: | 10.1186/1476-0711-10-8 1476-0711 |