Performance of BD MAX Group B Streptococcus (GBS) Assay without Enrichment for the Detection of GBS

Accuracy of real-time polymerase chain reaction test for Group B Streptococcus detection in pregnant women: A systematic review and meta-analysis

OBJECTIVES

This study aimed to determine the performance of RT PCR of GBS screening in pregnant women under different situations, especially compared to different reference methods (culture or composite standards) and preprocessing before detection (directly or enrichment).

MATERIALS AND METHODS

We searched PubMed, the Cochrane Library: Cochrane Database of Systematic Reviews, EMBASE, and Google Scholar, and clinical trial registries such as ClinicalTrials.gov and WHO ICTRP until March 2024. The assessment of each study quality was performed using a modified QUADAS-2 instrument. The meta-analysis included pooled sensitivity, specificity, summary receiver operating characteristic (SROC) curve, and AUC. Publication bias was examined using Deek's funnel plot. Sensitivity analysis was conducted to evaluate the robustness of the meta-analysis. Index (I-square) and Q-test were performed to analyze the heterogeneity, and subgroup analysis and logistic meta-regression were used to identify the potential causes.

RESULTS

A total of 81 reports, including 133 research, were involved in the analysis. The pooled sensitivity and specificity of RT-PCR for detection of Group B Streptococcus in pregnant women were 96 % (95 %CI: 94 %-97 %) and 98 % (95 %CI:97 %-98 %), respectively. The pooled AUC value was 0.99 (95 %CI:0.98-1.00). In subgroup studies, there were four groups, including Group A (Enrichment & culture), Group B (Direct & culture), Group C (Enrichment & composite standard), and Group D (Direct & composite standard). Group A's pooled sensitivity and specificity were 98 % (95 %CI: 97 %-99 %) and 94 % (95 %CI:92 %-96 %), respectively. Group B's pooled sensitivity and specificity were 92 % (95 %CI: 89 %-94 %) and 96 % (95 %CI:95 %-97 %), respectively. Group C's pooled sensitivity and specificity were 98 % (95 %CI: 97 %-99 %) and 99 % (95 %CI: 99 %-99 %), respectively. Group D's pooled sensitivity and specificity were 93 %(95 %CI: 87 %-97 %) and 100 % (95 %CI:99 %-100 %), respectively. The pooled AUC values of the SROC for groups A, B, C, and D were 0.99 (95 %CI: 0.98-1.00), 0.98(95 %CI: 0.97-0.99), 1.00 (95 %CI: 0.99-1.00), and 0.99(95 %CI: 0.99-1.00), respectively.

Development and performance evaluation of a qPCR-based assay for the fully automated detection of group B Streptococcus (GBS) on the Panther Fusion Open Access system

Streptococcus agalactiae [group B Streptococcus (GBS)] poses a major threat as the primary cause of early-onset neonatal invasive disease, particularly when mothers are colonized rectovaginally. Although culture remains the gold standard for antepartum GBS screening, quantitative polymerase chain reaction (qPCR) offers advantages in terms of sensitivity and turnaround time. The aim of this study was to validate the clinical utility of an automated qPCR laboratory-developed test (LDT) for antepartum GBS screening using the Panther Fusion Open Access system (Hologic, California, USA). The LDT targeted a conserved region of the GBS surface immunogenic protein gene, demonstrating no cross-reactivity and high coverage (99.82%-99.99%). The limit of detection (LoD) was 118 CFU/mL. Comparison with commercial qPCR assays (Panther Fusion GBS and VIASURE Streptococcus B Real-Time) revealed an overall agreement of 99.7%, with a robust Cohen's kappa coefficient of 0.992. Testing of 285 rectovaginal swabs from pregnant women and 15 external quality assessment samples demonstrated exceptional diagnostic performance of the LDT, achieving a diagnostic sensitivity and specificity of 100%, underscoring its accuracy. Prevalence and predictive values were also determined to reinforce test reliability. Our research highlights the limitations of culture-based screening and supports the suitability of our qPCR-based LDT for GBS detection in a clinical setting.IMPORTANCERectovaginal colonization by GBS is a major risk factor for early-onset invasive neonatal disease. The most effective approach to reducing the incidence of early-onset disease (EOD) has been described as universal screening, involving assessment of GBS colonization status in late pregnancy and intrapartum antibiotic prophylaxis. Despite its turnaround time and sensitivity limitations, culture remains the gold standard method for GBS screening. However, nucleic acid amplification-based tests, such as qPCR, have been utilized due to their speed and high sensitivity and specificity. This study validated the clinical usefulness of an automated qPCR-LDT for antepartum GBS screening through the Panther Fusion Open Access system (Hologic). Our study addresses the critical need for more robust, sensitive, and rapid strategies for GBS screening in pregnant women that could favorably impact the incidence of EOD.

A small-scale external quality assessment for PCR detection of group B streptococcus in China

BACKGROUND

Group B streptococcus (GBS) is considered a leading cause of maternal and infant morbidity and mortality. Molecular diagnosis is a routinely used approach for GBS screening to protect pregnant women and prevent early-onset GBS neonatal disease. The objective of this study was to identify issues and guarantee the dependability of GBS molecular diagnosis by an external quality assessment (EQA) scheme.

METHODS

The EQA panel comprised eight samples spiked with 10-fold dilutions of GBS suspension (20-2,000,000 copies/mL), and 2 negative control samples. The panels were coded randomly and distributed to participating laboratories for GBS detection.

RESULTS

In total, 44 participating laboratories submitted results with eight commercial GBS PCR assays and one in-house assay. Among them, 36 obtained an acceptable or higher performance score, while 8 required improvement. Among the 440 results returned, 62 (14.1 %) were incorrect, including 5 false positives and 57 false negatives.

CONCLUSIONS

Our small-scale EQA showed that most participating laboratories have reliable diagnostic capacities for GBS PCR detection. Nonetheless, further improvements in the detection performance of some laboratories are required, particularly with low-concentration samples. Our survey also reinforces the use of EQA as an essential tool to evaluate the overall proficiency of clinical laboratories.