Rapid detection of group B streptococci in pregnant women at delivery

Background: Group B streptococcal infections are an important cause of neon atal morbidity and mortality. A rapid method for the detection of this orga nism in pregnant women at the time of delivery is needed to allow early tre atment of neonates. Methods: We studied the efficacy of two polymerase-chain-reaction (PCR) ass ays for routine screening of pregnant women for group B streptococci at the time of delivery. We obtained anal, vaginal, and combined vaginal and anal specimens from 112 pregnant women; in 57 women, specimens were obtained be fore and after the rupture of the amniotic membranes. The specimens were te sted for group B streptococci by culture in a standard selective broth medi um, with a conventional PCR assay, and with a new fluorogenic PCR assay. Results: Among the 112 women, the results of the culture of the combined va ginal and anal specimens were positive for group B streptococci in 33 women (29.5 percent). The two PCR assays detected group B streptococcal coloniza tion in specimens from 32 of these 33 women: the one negative PCR result wa s in a sample obtained after the rupture of membranes. As compared with the culture results, the sensitivity of both PCR assays was 97.0 percent and t he negative predictive value was 98.8 percent. Both the specificity and the positive predictive value of the two PCR assays were 100 percent. The leng th of time required to obtain results was 30 to 45 minutes for the new PCR assay, 100 minutes for the conventional PCR assay, and at least 36 hours fo r culture. Conclusions: Colonization with group B streptococci can be identified rapid ly and reliably by a PCR assay in pregnant women in labor both before and a fter the rupture of membranes. (N Engl J Med 2000;343:175-9.) (C)2000, Mass achusetts Medical Society.