Bacterial flora of the vagina: quantitative study.

Quantitative analysis of cultures of the vaginal flora was performed on 118 specimens from 68 women of reproductive age. Aerobic bacteria in concentrations greater than 10(5) organisms/g were recovered in all specimens. The mean concentration of aerobes was 10(8.1) organisms/g, and lactobacilli were the most common isolates. Anaerobes were recovered from 86% of the specimens, and the mean concentration of these organisms, when present, was 10(8.6) organisms/g. The most commonly occurring anaerobes were peptococci and anaerobic gram-positive bacilli. Analysis of specimens obtained sequentially during a menstrual cycle showed significant qualitative and quantitative changes. Cervical cultures showed bacteriologic patterns that were similar to those noted with vaginal cultures. However, duplicate samplings of the cervix and vagina in individual patients showed substantial differences in the bacteria recovered. These observations suggest that the vaginal flora is a dynamic ecosystem that is subject to change and that the cervix represents a unique ecologic niche.