ENHANCED ANTENATAL DETECTION OF GROUP-B STREPTOCOCCUS COLONIZATION

Objective: To improve culture methods for the detection of group B streptococcus colonization. Methods: This study prospectively compared the standard culture medium, a blood agar plate, to a selective culture medium, Todd Hewitt broth with antibiotics, and compared vaginal culture with rectal culture at the first prenatal exam. Results: Of the 383 vaginal swabs received for evaluation of the two culture media, 78 (20.4%) were positive for group B streptococcus. The detection rates of the blood agar plate method and the Todd Hewitt broth with antibiotics were 64.1 and 97.4%, respectively. Using the Todd Hewitt broth with antibiotics, an additional 94 patients were cultured vaginally and rectally. Twenty-nine (30.9%) had positive cultures. The rate of detection was 58.6% for the vaginal culture, 89.7% for the rectal culture, and 100% for both culture sites combined. Conclusion: These data indicate that culture detection of group B streptococcus can be improved by using both a selective broth medium and a dual vaginal and rectal culture.