A Comparison of Two Enrichment Broth Medium for the Isolation and Identification of Streptococcus agalactiae from Vaginal Swabs

Abstract

Aim: To evaluate the performance of brain heart infusion (BHI) versus Todd-Hewitt (TH) media for the culture and identification of Group B Streptococcus (GBS) in vaginal swabs from pregnant women in last trimester. Two enrichment broth media were compared in terms of sensitivity, accuracy and cost. Methodology: 242 vaginal samples collected during March and May 2018 from Tam Anh hospital were included in this study. Each sample was collected in duplicated swabs, each swab was then cultured in BHI and TH broth and following the same method in accordance with the manufacturers’ guidelines. Results: BHI had excellent diagnostic performance compared to TH, with sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 91.30%, 100%, 100%, 98.00% and 98.35%, respectively. BHI decreased material and supply costs 88.31%. Conclusion: BHI was chosen for introduction into routine use, due to its better sensitivity and accuracy, meanwhile lower cost than TH.