Comparison of Urine Specimen with Recto-Vaginal Swab to establish carriage of Group B Streptococcus Colonization in Pregnant Females

Abstract

Objective: To determine maternal vaginal colonization with Group B Streptococcus using both recto-vaginal swab and mid-stream urine in order to determine which specimen type can give better results. Study Design: Cross-sectional study. Place and Duration of Study: Armed Forces Institute of Pathology, Rawalpindi Pakistan, Department of Gynecology and Obstetrics, Combined Military Hospital and Pak Emirates Military Hospital, Rawalpindi Pakistan, from Jan to Jun 2022. Methodology: Recto-vaginal swabs and mid-stream urine were taken from 194 pregnant women between 36th and 37th weeks of pregnancy. Swabs were inoculated on blood and MacConkey agar while urine specimen was inoculated on blood and CLED agar. All plates were incubated at 37°C in either ambient air or CO₂ incubator. Identification of Group B Streptococcus was made on the basis of colony morphology (β-haemolytic colonies on blood agar), Gram stain, catalase test and confirmation were done by means of latex agglutination tests. Results: In comparison to urine, a Group B Streptococcus carriage rate of 8.2% was detected in recto-vaginal swab. Urine specimen of only 3 patients yielded growth of Group B Streptococcus giving a urine carriage rate of 1.5%. Conclusion: Recto-vaginal swab gives a better insight to the presence of Group B Streptococcus as compared to mid-stream urine.