Background The normal vaginal flora is primarily composed of Lactobacillus spp., which maintain the vaginal pH and create an inhospitable environment for other organisms. Bacterial vaginosis (BV) is a polymicrobial condition with low Lactobacillus spp. count and an increase in organisms such as Mycoplasma hominis and Garderella vaginalis. BV is associated with increased risk of acquisition of STDs/HIV and pregnancy-related morbidities. In this study, we described the general vaginal flora as well as the Lactobacillus spp of 10 healthy women and 10 women with BV in the Bay Area, California, USA.

Methods Between July 2009 and April 2010, we obtained vaginal swabs from 10 healthy women and 10 women with BV at the San Francisco City Clinic with informed consent. BV status was determined by Nugent scoring. The swabs were cultured in anaerobic conditions on Columbia agar, for unspecific bacterial growth, and on Rogosa agar, selective for Lactobacillus spp. By sequencing PCR amplifications of the 16srRNA gene, 5 to 10 single bacterial colonies from both agars were identified at the species level in all samples.

Results A total of 277 bacterial colonies were successfully sequenced from healthy women (143) and women with BV (134). A wide range of organisms were identified in both groups. Corynebacterium spp were found in healthy women (11, 7.7%) and women with BV (25, 18.5%). Enterococcus faecalis was present in both groups (BV−: 15, 10.5%; BV+: 10, 7.5%). Streptococcus spp were found as well (BV−: 9, 6.3%; BV+: 15, 11.6%). Staphylococcus spp. were isolated (BV−: 28, 19.6%; BV+: 22, 16.2%), with S epidermis being the most common (BV−: 15, 10.5%; BV+: 7, 5.2%). Interestingly, Gardnerella vaginalis was isolated in one healthy woman in addition to women with BV (7, 5.2%). Lactobacillus spp. were found with higher frequency in healthy women (BV−: 68, 46.2%; BV+: 28, 20.8%). The most common species in healthy women were: L crispatus (42, 62% of total Lactobacillus spp.) and L jensenii (11, 16.2%). In women with BV, the most common was L coleohominis (17, 61%) see Abstract P3-S7.19 table 1.

Conclusions This pilot study with a sample size of 20 women gave important information regarding the diversity of the vaginal flora in healthy women and women with BV. There is a clear switch in Lactobacillus spp. dominance in health women vs women with BV. This finding sheds light on the association of specific Lactobacillus spp. with bacterial vaginosis.