Inhibitors of Neisseria gonorrhoeae produced in liquid medium by Bacteroides fragilis and Eubacterium limosum.

Indigenous micro-organisms of the urogenital flora including anaerobes can inhibit the in vitro growth of Neisseria gonorrhoeae. Bacteroides fragilis and Eubacterium limosum strains known to inhibit the gonococcal growth on solid medium have been shown to produce their antigonococcal activities in liquid medium. Concentrations of individual short-chain fatty acids produced by E. limosum strains were lower than the inhibitory concentrations reported for N. gonorrhoeae. B. fragilis strains produced propionic acids in amounts known to be inhibitory to the gonococcus. Furthermore, studies with E. limosum (Ps11A) cultures incubated at 29 degrees C (200 ml, 50 l) and at 37 degrees C (200 ml) have shown that short-chain fatty acids were not the inhibitors since no correlation between the short-chain fatty acids and the antigonococcal activity was found throughout the growth of the cultures. Moreover, the observed inhibitory activity of E. limosum was not due to pH change or to nutrient depletion of the medium. These observations coupled with the specificity of the antigonoccal activity produced by E. limosum suggest that it is different from previously reported gonococcal inhibitors of bacterial origin.