Muzny CA, et al. - The researchers aimed at assessing the sequence of events preceding incident BV (iBV). They followed African American women who have sex with women (AAWSW) with no Amsel criteria and Nugent score 0-3 for iBV (Nugent score 7-10 on at least 2-3 consecutive days) with self-collected vaginal swabs for 90 days. L. crispatus dominated in 75% of women maintaining normal vaginal flora. In contrast 79% of cases were dominated by L. iners and/or L. jensenii/L. gasseri prior to iBV. The mean relative abundance of P. bivia, G. vaginalis, A. vaginae, and Megasphaera-type I became significantly higher in cases 4 days before, 3 days before, and on the day of iBV (A. vaginae and Megasphaera-type I). Thereby suggesting significant roles of G. vaginalis, P. bivia, A. vaginae, and Megasphaera-type I in iBV.