Estimation of Group B Streptococcus Colonization in High-Risk Neonates by PCR and Standard Culture

Background: group b streptococcus (gbs) (streptococcus agalactiae) is the leading cause of morbidity and mortality of newborn infants considered a leading factor causing septicemia after birth. the standard method for the diagnosis of gbs colonization is culture in a selective medium, but pcr has a high sensitivity and specificity. objectives: the goal of this study was to estimate the colonization of gbs in rectum of neonates of high-risk mothers by culture and pcr method. patients and methods: samples were taken from rectal mucosa of 154 neonatesof high-risk mothers for gbs by swabs. samples were tested by standard culture using todd hewitt broth and blood agar and also by pcr using primers specific for cfb gene. results: of 154 neonates, culture identified 17 (11%) neonates as colonized by gbs; and the pcr assay could identify 27 (17%) neonates with positive results for gbs. mothers age range was 17-40 years (mean = 26.1 ± 5.1). maternal age was significantly lower in pcr positive group (p = 0.038) and in culture positive group (p = 0.015). using culture as the gold standard, sensitivity, npv, specificity, and ppv of pcr were 100%, 100%, 92%, and 62%, respectively. the time required for pcr assay and culture were 2hours and 36hours, respectively. conclusions: this study showed that the incidence of gbs in iranian high-risk neonates is high, so we strongly recommend screening of high-risk neonates for detection of gbs.