Intrapartum group B Streptococcus screening in the labor ward by Xpert® GBS real-time PCR.

Group B Streptococcus (GBS) is the leading cause of neonatal infections in industrialized countries. Intrapartum antibiotic prophylaxis (IAP) given to colonized parturients is a key step for the prevention of neonatal early-onset infection. We compared the performances of Xpert® GBS polymerase chain reaction (PCR) (Cepheid, Sunnyvale, CA, USA) as a point-of-care system in labor wards to standard culture for intrapartum GBS detection. Pregnant women with a GBS-positive antenatal screening were prospectively included. A vaginal double swab was collected at the time of delivery for point-of-care Xpert® GBS PCR and GBS culture. A total of 565 pregnant women were included. Valid Xpert® GBS results were obtained for 488 (86.4%) women on the first attempt. Repeat testing improved the PCR success to 516 (91.3%) women. Among the 305 women positive for GBS by culture at delivery, only 238 (78.0%) were positive by Xpert® GBS PCR, cycle thresholds being correlated to culture quantification. Among 260 women negative for GBS culture, 56 (21.5%) were positive by Xpert® GBS PCR, including 50 where IAP was initiated before vaginal sampling. Overall, among the 565 women with GBS antenatal positive culture, only 335 (59.3%) were still positive at delivery whatever the technique used, resulting in unnecessary IAP for 40% of them. This large cohort study comparing intrapartum to antepartum GBS detection provides evidence that (i) Xpert® GBS PCR might be a valuable solution for intrapartum GBS detection compared to culture-based strategies and (ii) laboratory training of non-specialized staff is mandatory to reach the performances required for point-of-care tests.

Group B streptococcus neonatal invasive infections, France 2007-2012.

Streptococcus agalactiae (group B streptococcus (GBS)) is the leading cause of invasive infections among newborns in industrialized countries, with two described syndromes: early-onset disease (EOD) and late-onset disease (LOD). Since the introduction in many countries of intrapartum antibioprophylaxis (IAP), the incidence of EOD has dramatically decreased, whereas that of LOD remains unchanged. We describe the clinical and bacteriological characteristics of 438 GBS neonatal invasive infections notified to the French National Reference Centre for Streptococci in France from 2007 to 2012. Clinical data were retrieved from hospitalization reports or questionnaires. Capsular type, assignment to the hypervirulent clonal complex (CC)17 and antibiotic susceptibility profiles were determined. One hundred and seventy-four (39.7%) and 264 (60.3%) isolates were responsible for EOD, including death in utero, and LOD, respectively. EOD was associated with bacteraemia (n = 103, 61%) and LOD with meningitis (n = 145, 55%). EOD was mainly due to capsular polysaccharide (CPS) III isolates (n = 99, 57%) and CPS Ia isolates (n = 40, 23%), and CPS III isolates were responsible for 80% (n = 211) of LOD cases. CC17 accounted for 80% (n = 121) of CPS III isolates responsible for meningitis (n = 151; total cases of meningitis, 188). Bad outcome risk factors were low gestational age and low birthweight. LOD represents almost 60% of cases of neonatal GBS disease in France and other countries in which IAP has been implemented. This observation reinforces the need to develop new prevention strategies targeting CC17, which is predominant in GBS neonatal infections.