Evaluation of Culture, Antigen Detection and Polymerase Chain Reaction for Detection of Vaginal Colonization of Group B Streptococcus (GBS) in Pregnant Women

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 GBS in Pregnant women.

SETTINGS AND DESIGN: Observational descriptive study was done in a tertiary care hospital in Southern India.

MATERIALS AND METHODS: 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.