The isolation and identification of Bacteroides ssp. from the normal human vaginal flora

The occurrence of gram-negative anaerobic bacilli in the normal vaginal flora was studied in 20 normal healthy women attending a family-planning clinic. A swab was taken from the cervix and posterior fornix and Bacteroides spp. were isolated on a selective medium from 13 (65%) subjects. A heavy growth of Bacteroides was obtained from 11 specimens but only a few colonies were isolated from two specimens. Where possible, 10 representative colonies from each subject were studied and 113 isolates were identified by conventional bacteriological tests. Most isolates (78%) belonged to the B. melaninogenicus/oralis group. The commonest species identified in this group were the B. bivius/disiens complex (42%), B. melaninogenicus ss. intermedius (22%) and ss. melaninogenicus (16%). Asaccharolytic strains were isolated in smaller numbers from 54% of subjects, but only five strains of the B. fragilis group were isolated from two subjects; fusobacteria were not detected.