Evaluation of culture, antigen detection and polymerase chain reaction for detection of vaginal colonization of group B streptococcus in pregnant women

Abstract

Background and Objective: Group B Streptococcal infection is an important cause of neonatal morbidity and mortality. Early detection of perinatal vagino-rectal (VR) carriage of Group B Streptococcus (GBS) is important in the management of newborn infections. The objective of the study was to evaluate Culture, antigen detection and Polymerase chain reaction for detection of Group B Streptococcus in Pregnant women. Settings and Design: Observational descriptive study was done in a tertiary care hospital in Southern India. Materials and Methods: Vagino-rectal (VR) swabs were collected from 50 women at 35 to 37 weeks of gestation. Culture in a selective Lim enrichment broth with subsequent culture on 5% sheep blood agar, Conventional PCR assay and antigen detection method were performed. The performance of antigen detection and PCR methods were compared with culture. Statistical analysis: Statistical analysis was performed by Chi-Square test. Results: GBS cultures were positive for 16% of the specimen (8 out of 50). Considering culture as a gold standard, Sensitivity, Specificity, Positive predictive value and Negative predictive value of antigen detection was 100%, 92.86%, 72.73%, 100% and similarly for that of PCR was 100%, 45.23%, 25.80%, 100%, respectively. Conclusion: Antigen detection method was the rapid, sensitive and specific test for the detection of GBS colonizers during pregnancy.