A study of the susceptibility of three species of primate to vaginal colonization with Gardnerella vaginalis.

In an attempt to develop an animal model of Gardnerella-associated vaginitis, several strains of Gardnerella vaginalis were inoculated into the lower genital tract of female pig-tailed macaques, tamarins and chimpanzees. G. vaginalis was not recovered from either tamarins or chimpanzees, but was recovered from each of 1O pig-tailed macaques inoculated with either of two freshly isolated Gardnerella strains, colonization persisting for 11-39 days. Examination of Gram-stained vaginal smears obtained from infected pig-tailed macaques failed to demonstrate clue cells, a feature which is pathognomonic of Gardnerella-associated vaginitis in humans. Other features characteristic of non-specific vaginitis, namely an increase in vaginal pH, and an increase in the ratio of succinate to lactate (S/L ratio) in vaginal fluid were not found. However, the physiology of the macaque vagina was found to be different from that of the human, the vaginal pH and S/L ratio of uninfected macaques both being higher than that seen in humans. The physiological differences between the macaque and human vagina may be due, in part, to a difference in their anaerobic vaginal flora. While these inter-species differences in vaginal physiology and microbiology limit the relevance of the pig-tailed macaque as a model of Gardnerella-associated vaginitis, the ease with which macaques are colonized with G. vaginalis may prove useful in studying bacterial adhesion and local immunity.

Vaginal colonization of pig-tailed macaques by Gardnerella vaginalis.

Ten pig-tailed macaques inoculated intravaginally with Gardnerella vaginalis organisms were colonized for 11-39 days. In contrast, 4 tamarins and 3 chimpanzees inoculated similarly failed to become colonized. Examination of Gram-stained vaginal smears obtained from infected pig-tailed macaques failed to demonstrate clue cells, a feature which is pathognomonic of non-specific vaginitis in humans. Additionally, the pH value, the levels of non-volatile fatty acids and the anaerobic flora of the macaque vagina differed from these aspects of the human vagina. While these differences indicate that gardnerella-infected macaques are unsuitable as a model of gardnerella-associated vaginitis in humans, such animals may prove useful for studying selected aspects of the biology of G. vaginalis such as the adhesion and interaction of the bacteria with the vaginal mucosa.

Non-volatile fatty acids in the diagnosis of non-specific vaginitis.

In the vaginal washings of 100 women with symptomatic non-specific vaginitis a succinate/lactate ratio of greater than or equal to 0.4 had a diagnostic sensitivity of 80%, a specificity of 83% for this condition. The predictive value of a positive test was 94%, but that of a negative test was only 55%. A strong association between the presence of Gardnerella vaginalis, anaerobes, a vaginal pH of above 4.5, and amines was found not only in non-specific vaginitis, but also in trichomonal and gonococcal infection. A variety of primary changes may encourage the multiplication of both gardnerellae and anaerobes and their presence in non-specific vaginitis may be a secondary rather than a primary event.