| Summary: | Anaerobes belonging to the genera Propionibacterium, Bacteroides, Peptococcus, Peptostreptococcus, Eubacterium, Streptococcus and Lactobacillus, which are commonly isolated from the human urogenital flora, were tested for their ability to inhibit the in vitro growth of Neisseria gonorrhoeae strains. === The antigonococcal effect of the anaerobic bacterial strains tested was found not to be due to nutrient depletion and pH change of the media which had supported their growth. This inhibition was not an all-or-none phenomenon since an inhibitory strain did not necessarily interfere with all the gonococcal strains tested. === All the 23 lactobacilli strains tested were found to inhibit the in vitro growth of N. gonorrhoeae. This inhibition was found to be dependent on the composition of the culture medium. In comparison to the gonococcus (GC) and dextrose starch agar (DSA) media, a modified deMan, Rogosa et Sharpe (MRS) medium was more appropriate to support both the growth of lactobacilli and the production of their antigonococcal activity. === For the other 32 anaerobic bacterial strains tested, six were selected for their large antigonococcal spectrum of activity. These strains were Peptostreptococcus anaerobius (Pc9,Ps11B,Ps11C), Bacteroides fragilis (B1A), Bacteroides ovatus (B24) and Eubacterium limosum (Ps11A). The antigonococcal activity produced by these six strains appeared to be specific to the gonococcus since a variety of anaerobes and aerobes were not generally inhibited. === E. limosum and B. fragilis strains were further selected to evaluate the production of their antigonococcal activity in liquid medium. E. limosum Ps11A strain produced its inhibitory activity in prereduced brain heart infusion (BHI) broth during the mid-logarithmic phase of growth, when no inhibitory concentration of short-chain fatty acids was detected in the culture medium. Furthermore, when the amounts of short-chain fatty acids produced by E. limosum increased, its antigonococcal activity decreased. Based on these results and on the individual amount of short-chain fatty acids excreted by E. limosum strains, it was concluded that the observed antigonococcal activity was not due to the presence of these acids. However, B. fragilis strains excreted propionic acid in amount reported to be inhibitory to the gonococcus. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI
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