Comparison of LightCycler PCR and culture for detection of group B streptococci from vaginal swabs.

Group B streptococci (GBS) are an important cause of neonatal sepsis and meningitis. New rapid, sensitive and specific methods for detection of GBS in pregnant women are needed in order to provide timely treatment of neonates. The sensitivity, specificity and cost of a LightCycler PCR method was compared with selective culture for the detection of GBS from 400 vaginal swabs. In addition, two DNA extraction methods (simple boiling and automated DNA extraction by Roche MagNA Pure LC) were compared for a subgroup of 100 clinical samples. The sensitivity of the LightCycler PCR assay for the detection of GBS from vaginal swabs was significantly higher than that of culture. There were no culture-positive, LightCycler PCR-negative cases. The efficiencies of the two DNA extraction procedures were not significantly different. The detection of GBS from vaginal swabs by the molecular method (including simple boiling extraction) required the same hands-on time, but the procedure was completed in 1.5 h, compared with c. 48 h for the culture-based approach. Disadvantages of the molecular method are the increased costs (45%) and the absence of antibiogram data. The LightCycler PCR is a promising tool for sensitive, specific and rapid detection of GBS directly from clinical specimens of pregnant women.