Mobiluncus curtisii and recurrent bacterial vaginosis

Women with what’s known as ‘complicated vaginal flora’ have higher levels of Mobiluncus species, and are more likely to have recurrent bacterial vaginosis. Mobiluncus curtisii and M. mulieris are highly specific to BV, but they are not the only culprits. M. curtisii is the mostly likely to be involved in BV, and is resistant to metronidazole – the most commonly prescribed antibiotic for BV. The presence of M. curtisii and the recurrence of BV at 65-70 days post-antibiotic-treatment are associated.

Recurrent BV could be due to the inability of metronidazole to clear this bacteria from the vagina.

One study at an STI clinic in the United States took vaginal swabs, with 100 women symptomatic for BV enrolled, and treated for BV with antibiotics. All women took metronidazole for seven days or 14 days, plus or minus azithromycin. Study subjects were checked at 21, 35-40, and 65-70 days after the start of the study. If a subject had recurrence of symptomatic BV, they were discontinued from the study, however if BV was asymptomatic, they were kept in the study.

Vaginal swabs and polymerase chain reaction (PCR) tests were performed at baseline and at each follow-up visit. The women in the study had M. curtisii present at baseline (detected by PCR) with three follow-up visits. Recurrence of BV at 65-70 days was defined as a Nugent score of 7-10 regardless of symptoms. Persistence of M. curtisii was defined as the organism being present at baseline and at at least one of the follow-up visits.

Persistence of M. curtisii at baseline and at least one other visit was significantly associated with a recurrence of BV. Almost 68 per cent of the women with persistent M. curtisii had a recurrence of BV compared with 11 per cent of women who had no evidence of M. curtisii by PCR after the baseline treatment visit.

The way that M. curtisii shows up in the PCR testing was of note, since the organism either didn’t show up in visits two and three (after treatment), but visit four, or the organism was present in all tests. The former may indicate reinfection, while the latter may indicate a lack of clearance, however they could both mean a lack of clearance.


MELTZER MC, DESMOND RA, SCHWEBKE JR. Association of Mobiluncus curtisii With Recurrence of Bacterial VaginosisSexually transmitted diseases. 2008;35(6):611-613. doi:10.1097/OLQ.0b013e318167b105.