GBS screening on term pregnancies: cultural or PCR

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.

研究目标：本研究的目的是评估通过产前聚合酶链反应对B族链球菌定植进行筛查，能否相较于产前培养筛查提高产时抗生素预防性给药的效率，并分析聚合酶链反应测试的敏感性和特异性。
研究方法：纳入了198名产前培养筛查出B族链球菌定植的孕妇。当她们入院分娩时，收集了两个直肠阴道拭子：一个用于培养，另一个用于聚合酶链反应方法。
研究结果：通过培养检测到的产前B族链球菌定植率为16.7%；分娩时，通过培养检测到的定植率为17.2%，而使用聚合酶链反应方法检测到的定植率为19.7%。聚合酶链反应测试结果不确定的比例为0.5%。以产时培养筛查为金标准，聚合酶链反应测试对产时B族链球菌定植的敏感性和特异性分别为97.1%和95.7%。产前与产时B族链球菌定植不一致的总体率为6.6%。在产时培养筛查结果为阳性的情况下，使用产时聚合酶链反应测试未接受产时抗生素预防性给药的妇女比例（0.5%）显著低于使用产前培养方法的比例（3.5%，p=0.035）。
研究结论：当通过聚合酶链反应测试进行产时B族链球菌定植筛查时，使用产时抗生素预防性给药的效率可以更高。本研究中，聚合酶链反应方法表现出良好的性能，具有较高的敏感性和特异性。