Association of bactericidal activity of genital tract secretions with Escherichia coli colonization in pregnancy

Objective Genital tract secretions exhibit bactericidal activity against Escherichia coli . We hypothesized that this defense may be modulated during pregnancy. Study Design Secretions were collected by vaginal swab from 70 pregnant women (35-37 weeks' gestation) and 35 nonpregnant controls. We mixed E coli with swab eluants or control buffer and colonies enumerated to measure bactericidal activity. Cytokines, chemokines, and antimicrobial peptides were quantified by multiplex or enzyme-linked immunosorbent assay. Results Pregnant women had significantly greater bactericidal activity, higher concentrations of proinflammatory cytokines, and lower levels of beta defensins compared to controls. Seven (10%) pregnant and 8 (23%) nonpregnant women were vaginally colonized with E coli ; colonization was inversely associated with bactericidal activity. Conclusion The soluble mucosal immune environment is altered in pregnancy. We speculate that the observed changes may protect against colonization and ascending infection and could provide a biomarker to identify pregnant women at risk for infectious complications including preterm birth.