Group B Streptococcus rectovaginal colonization screening on term pregnancies: culture or polymerase chain reaction?

Objectives: The aim of this study was to evaluate if screening Group B Streptococcus colonization by intrapartum polymerase chain reaction could improve intrapartum administration of antibiotic prophylaxis, compared with antepartum culture screening and analyze the sensitivity and specificity of polymerase chain reaction test.Methods: 198 pregnant women with Group B Streptococcus colonization antepartum culture screening were included. When they arrived at hospital for delivery, two rectovaginal swabs were collected: for culture and polymerase chain reaction method.Results: The rate of Group B Streptococcus colonization antepartum detected by culture was 16.7%; at delivery was 17.2% when detected by culture and 19.7% using polymerase chain reaction method. The rate of inconclusive polymerase chain reaction tests was 0.5%. Considering intrapartum culture screening as gold standard, sensitivity and specificity of polymerase chain reaction test for intrapartum Group B Streptococcus colonization was 97.1% and 95.7%, respectively. The global rate of discordance between antepartum and intrapartum Group B Streptococcus colonization was 6.6%. The rate of women not treated with intrapartum antibiotic prophylaxis in the setting of positive intrapartum culture was significantly lower using intrapartum polymerase chain reaction test (0.5%) than with antepartum culture method (3.5%, p = 0.035).Conclusion: The use of intrapartum antibiotic prophylaxis can be more efficient when screening Group B Streptococcus colonization intrapartum by polymerase chain reaction test. Polymerase chain reaction method had a good performance in our study, with high sensitivity and specificity.