Comparison of Combined Vaginal-Anorectal, Vaginal and Anorectal Cultures in Detecting of Group B Streptococci in Pregnant Women in Labor
Ekachai Kovavisarach MD*, Warintorn Sa-adying MD*, Suwattana Kanjanahareutai MSc**
Affiliation : * Department of Obstetrics & Gynecology, Rajavithi Hospital, Ministry of Public Health, College of Medicine, Rangsit University ** Department of Pathology, Rajavithi Hospital, Ministry of Public Health
Objective : To compare whether the Group B streptococcal culture detection rate from vaginal-anorectal
cultures, vaginal, or anorectal are equivalent.
Materials and Methods : Cross-sectional descriptive study was performed on 320 pregnant women with a
gestational age between 28-42 weeks presenting with labor pain, between October, 1 and 30, 2004 in Rajavithi
Hospital. Anorectal and vaginal swab cultures were collected and cultured in Todd Hewitt broth with 15 µg/
ml nalidixic acid and 8 µg/ml gentamicin.
Results : Forty-three (13.44%) and 33 cases (10.31%) were not significantly different in GBS detection rate in
vaginal and anorectal culture, respectively (p = 0.154, McNemar). Combined vaginal-anorectal culture
significantly improved the colonization GBS detection rate to 18.12% compared with either individual vaginal
or anorectal culture l (p < 0.001, McNemar).
Conclusion : GBS detection rate from combined vaginal-anorectal was significantly higher than either indi-
vidual vaginal or anorectal cultures.
Keywords : Group B streptococcous, Vaginal culture, Anorectal culture, GBS, Rajavithi Hospital
