Prevention of neonatal infection caused by group B streptococci

Objective. To evaluate the prevalence of vaginal carriage of Streptococcus agalactiae among pregnant women at 35–37 weeks of gestation and assess the efficacy of intrapartum antibiotic prophylaxis (IAP) for group B streptococcus (GBS) infection in newborns. Patients and methods. We examined 800 pregnant women at 35–37 weeks of gestation (bacteriological examination of vaginal microbiota with biomaterial collected from the posterior vaginal fornix). Identified carriers of S. agalactiae who had vaginal delivery (n = 50) received antibiotic prophylaxis to prevent infection in newborns. We also evaluated the frequency of vertical transmission of streptococci in all infants during the first hour of life (bacteriological examination of pharyngeal swabs and meconium). Identification of microorganisms was performed by direct protein profiling using MALDI-TOF mass spectrometry (FLEX series, Bruker Daltonic GmbH, Germany). Results. Maternal vaginal colonization with S. agalactiae in the third trimester was observed in 13.5% of patients tested (n = 108). Fifty women had vaginal delivery and received antibiotic prophylaxis to prevent infection in newborns. Postpartum samples of only 1 newborn gave scanty growth of S. agalactiae at bacteriological examination (1 × 101 CFU/mL in meconium and 1 × 103 CFU/mL in the pharyngeal sample), while the remaining 49 newborns had sterile samples. Thus, the frequency of S. agalactiae vertical transmission with intrapartum antibiotic prophylaxis was 2% (n = 1). Of note, infection in the newborn caused no inflammation. Conclusion. Relatively low prevalence of vaginal carriage of S. agalactiae among pregnant women gives no sufficient grounds for the inclusion of such bacteriological examination into compulsory screening for infections in pregnant women in the Russian Federation. However, intrapartum antibiotic prophylaxis is an effective method to prevent streptococcal infection in newborns; it should be used in women at risk of GBS infections. Kew words: vaginal carriage of bacteria, intrapartum antibiotic prophylaxis, neonatal sepsis, Streptococcus agalactiae, intrauterine infection, screening for infections