Choice of antibiotic for group B streptococcus in women in labour based on antibiotic sensitivity testing

To determine whether pregnant women testing positive for Group B Streptococcus (GBS) are receiving appropriate antibiotic prophylaxis in labour based on sensitivity testing.

We performed a retrospective chart review of all women who delivered at our institution from January 1 to December 31, 2008. We identified all GBS-positive women, and then abstracted data regarding demographic characteristics, method of GBS detection (recto-vaginal or urine culture), prevalence, and antibiotic use. The main outcome measure was the proportion of GBS-positive women who were managed appropriately.

During the study period 628 (22%) of 2878 women were identified as having GBS-positive cultures. Sensitivity testing was available for 481 of the recto-vaginal cultures. All were sensitive to penicillin. The rates of resistance for recto-vaginal culture were 22% for erythromycin, 19% for clindamycin, and 18% for both. Four hundred eighty-one women (93%) were treated with penicillin, 30 (6%) with clindamycin, three with cefazolin, and two with vancomycin. One hundred nine women (17%) who were GBS-positive did not receive antibiotics. Forty-four women (9%) did not receive appropriate antibiotic prophylaxis based on sensitivity testing.

Most GBS-positive women at our institution received an appropriate antibiotic during labour based on sensitivity testing. Our population reflects the Canadian GBS-positivity rate, which is similar to those observed in published studies from other populations. Future work should focus on developing strategies that re-emphasize GBS testing and treatment guidelines for prenatal care providers and on systems to ensure GBS-positive women are given the appropriate antibiotics during labour.