Prospective evaluation of a real-time PCR assay for detection of group B streptococci in vaginal swabs from pregnant women

Excerpt

Group B streptococci (GBS) is the leading cause of neonatal sepsis and meningitis in developed countries. Implementation of selective intrapartum antimicrobial prophylaxis (IAP) as part of either screening-based or risk-based strategies has lowered the incidence of early-onset GBS sepsis in the USA and other Western countries [1‐3]. Identification of GBS-colonized women is critical for the prevention of neonatal GBS infections [3‐5]. Collection and testing of swab specimens at 35–37 weeks’ gestation is one suggested screening-based approach. Although culture is still the gold standard method for detecting GBS, results are available only after 18–72 h, depending upon the use of selective broth medium. In order to decrease the processing time, rapid tests based on immunological or hybridization methods have been developed, but they are insufficiently sensitive for direct identification of GBS from vaginal-rectal samples [5‐9]. To overcome these problems, rapid-cycle real-time PCR methods have been developed for the detection and quantification of infectious agents. These assays are easy to perform and can be completed in as little as 30–60 min. Bergeron et al. [3, 10, 11] developed a real-time PCR assay for the detection of GBS from vaginal samples. Their test is based on the amplification of cfb, the gene encoding the Christie-Atkins-Munch-Petterson (CAMP) factor, and has been shown to be highly specific and sensitive. In the study reported here, we prospectively evaluated the efficiency of this real-time LightCycler PCR assay for detecting GBS in vaginal swabs obtained from pregnant women. The accuracy, time to completion, laboratory equipment and labor organization requirements of this PCR method were compared with that of standard culture. …