Vaccine and Infectious Disease Division

Insidious, fastidious bacteria

Bacterial vaginosis (BV) is a common infection among women and is associated with increased risk of preterm labor during pregnancy.  BV-infected women who are pregnant and treated with the antibiotic metronidazole have less BV-causing bacteria but are just as likely to deliver preterm.  New detection methods have found several bacterial species that were previously not known to be involved in BV.   These bacteria– termed “fastidious bacteria”– had previously gone undetected because they don’t grow well in lab cultures.  VIDI affiliate investigator Dr. Caroline Mitchell and her colleagues used sensitive DNA detection to study these fastidious bacteria in pregnant women taking metronidazole. They found that most BV-associated bacteria decrease significantly following treatment, even those resistant to metronidazole treatment.   Concentrations of two fastidious species decreased with oral but not vaginal metronidazole, but the rate of preterm labor was not different in these women.  This suggests that the response of the community of microbes to antibiotic treatment may be more clinically important than the response of any individual species.

Comparison of oral and vaginal metronidazole for treatment of bacterial vaginosis in pregnancy: impact on fastidious bacteria.  Mitchell CM et al.  BMC Infect Dis. 2009 Jun:89.