Evaluation of Diagnostic Accuracy of Revogene Automated Real-Time PCR System and Immunochromatographic Assay for Rapid Detection of Group B Streptococcus: A Prospective Methodological Comparison Study

Background: Group B Streptococcus (GBS) is the main pathogen of early-onset neonatal sepsis. Rapid and accurate intrapartum screening is crucial for guiding antibiotic prophylaxis. The traditional culture method is time-consuming, while the immunochromatographic assay has potential risks of insufficient sensitivity.Objective: To prospectively compare the diagnostic performance of the Revogene automated real-time PCR system and immunochromatographic assay for rapid GBS detection in a real laboratory environment.Methods: A total of 168 vaginal-rectal swab samples from pregnant women at 35-37 weeks of gestation were consecutively enrolled. Each sample was divided into three equal parts, which were tested in parallel and blindly using the Revogene PCR assay, immunochromatographic assay, and traditional culture method (combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, MALDI-TOF MS identification). The true GBS status of samples was determined by a composite reference standard (consistent results of two rapid methods + arbitration by traditional culture method when results were inconsistent). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and 95% confidence intervals (CI) of the two rapid detection methods were calculated and compared. Meanwhile, the detection time and cost were analyzed.Results: Among the 168 samples, 22 were confirmed as GBS-positive and 146 as GBS-negative by the composite reference standard. The sensitivity, specificity, PPV, and NPV of the Revogene PCR assay were 90.9% (95% CI: 58.7%-99.8%), 98.6% (95% CI: 92.5%-100.0%), 90.9% (95% CI: 58.7%-99.8%), and 98.6% (95% CI: 92.5%-100.0%), respectively. For the immunochromatographic assay, the corresponding indices were 27.3% (95% CI: 6.0%-61.0%), 97.3% (95% CI: 90.5%-99.7%), 60.0% (95% CI: 14.7%-94.7%), and 89.9% (95% CI: 81.0%-95.5%), respectively. Subgroup analysis showed that the detection rate of the immunochromatographic assay in the low-load group (