A new integrated extraction and real-time PCR-based system for the detection of group B streptococci in antepartum screening samples enriched in Lim broth was compared to the CDC-recommended culture method. The BD Max GBS assay exhibited acceptable sensitivity (95%) and specificity (96.7%) compared to those of the culture method in this multisite evaluation.The number of neonatal group B streptococcus (GBS) infections has decreased significantly over the past 4 decades; however, GBS still remains one of the most common causes of neonatal sepsis in the United States (3). Current management guidelines recommend that all pregnant women be screened for vaginal/rectal GBS colonization at 35 to 37 weeks of gestation, with those found to be colonized receiving intrapartum antibiotic prophylaxis.While culture-based methods have historically been the gold standard for demonstrating GBS colonization, several recent studies have demonstrated the utility of PCR-based detection as a sensitive and specific alternative (1, 2, 4-6, 8, 9). The BD Max GBS assay (BDM) implemented using the BD Max system (previously known as the HandyLab Jaguar system; BDHandyLab, Ann Arbor, MI) is one such PCR-based alternative. The BD Max system is a benchtop molecular diagnostic system, which provides fully automated clinical sample preparation, cell lysis, nucleic acid extraction, and mixing of nucleic acid with master mix reagents. With no user intervention, the system then dispenses the sample into a microfluidic chamber where real-time PCR amplification and detection are performed.The goal of this three-site investigational study was to compare the results obtained by BDM to those obtained by the CDC-recommended culture procedure, which served as the reference method (3). This study was designed to generate the data necessary for 510(k) submission to the FDA, so the study design, reference method, and evaluation criteria were performed as required by the FDA. Performance characteristics of the assay were derived from the results of 601 compliant specimens collected from antepartum women presenting for TRL obtained broth from Becton-Dickinson, Sparks, MD) and incubated for 18 to 24 h (as per protocol) prior to testing by either method. The growth obtained with each Lim broth was subcultured onto a sheep blood agar plate and incubated for up to 48 h. Colonies with morphology and color suggestive of GBS (both hemolytic and nonhemolytic) were Gram stained, tested for catalase production, and confirmed as GBS using latex agglutination (DCL and TRL used PathoDX Strep Grouping reagents, Thermo Fisher-Remel; UM used Slidex, bioMérieux, Durham, NC) and/or CAMP testing. BDM (cfb gene target and limit of detection of 200 CFU of GBS/ml of sample preparation reagent) (data not shown) was performed using a residual 15-l aliquot of Lim broth, and when possible, an alternate, validated PCR method was performed at each site (at DCL, the IDI-Strep B assay was performed on the Cepheid SmartCycler system with a cfb gene target; at TRL, the Roche analyte-specifi...