In bacterial vaginosis, the normal vaginal lactobacilli are replaced by various combinations of Gardnerella vaginalis, Bacteroides spp. and Mobiluncus spp. Products of anaerobic metabolism are present in the foul-smelling
non-inflammatory discharge. As markers of general metabolic activity, volatile and non-volatile fatty acids were measured in a series of pure and mixed cultures of Lactobacillus acidophilus, G. vaginalis, B. bivius and M. curtisi in Fastidious Anaerobe Broth. Growth and metabolic activity (propionate and isovalerate production) of M. curtisi were stimulated in mixed culture with
each of the other three species; stimulation was greatest by L. acidophilus. Lactate produced by G. vaginalis was reduced in M. curtisi-G. vaginalis mixtures. In M. curtisiB. bivius mixtures, isobutyrate was reduced but succinate increased. There were no interactions in mixtures of G. vaginalis with B. bivius or L. acidophilus, but growth and metabolic activity of B. bivius were markedly inhibited by L. acidophilus. In mixtures of three species, G. vaginalis had little effect; the metabolic patterns were generally those of the other pairs. In M. curtisi-B. bivius-L. acidophilus mixed culture, B. bivius was not inhibited; the amount of lactate was reduced, apparently metabolised to propionate by M. curtisi, and the predominant metabolites were those of B. bivius and M. curtisi. The addition of G. vaginalis to this mixture had no further effect.