Curved anaerobic bacteria in bacterial (nonspecific) vaginosis and their response to antimicrobial therapy

Vaginal fluid samples from normal college students, college students with bacterial (nonspecific) vaginosis, and sexually transmitted disease clinic patients with bacterial vaginosis, before and after therapy with metronidazole, ampicillin, or amoxicillin, were evaluated by direct Gram stain and culture for the predominant anaerobic and facultative flora. Curved rods were detected by direct Gram stain of vaginal fluid from 31 (51%) of 61 women with bacterial vaginosis and none of 42 normal student controls (P less than 0.001). Curved, gram-variable to gram-negative organisms were recovered from six of these 31 women, seven other women with bacterial vaginosis, and no controls. All 13 isolates were anaerobic, motile, and oxidase-negative, produced succinic acid as their major metabolic product, and hydrolyzed starch. After treatment with ampicillin or amoxicillin (n = 10) or greater than or equal to 2 g of metronidazole (n = 9), no curved motile rods were detected by Gram stain or culture, although the minimal inhibitory concentration of metronidazole was greater than or equal 8 micrograms/ml for 11 of the 13 isolates tested.