Atkins Kristin L, Atkinson Robyn M, Shanks Anthony, Parvin Curtis A, Dunne W Michael, Gross Gilad
Department of Obstetrics & Gynecology, Washington University in St. Louis, Saint Louis, Missouri 63110, USA.
Obstet Gynecol. 2006 Sep;108(3 Pt 1):488-91. doi: 10.1097/01.AOG.0000228961.42272.31.
The administration of antibiotic prophylaxis to laboring women who harbor Group B streptococci (GBS) depends on identification of carriers. We sought to evaluate the diagnostic accuracy of real-time polymerase chain reaction (PCR) for detection of GBS using a more stringent culture method.
Two swabs were used simultaneously to obtain rectovaginal GBS samples from consenting women. One swab was analyzed using a stringent, validated culture technology, which included direct plating onto selective agar and inoculation of a selective broth. The other swab was used for a commercial real-time PCR assay, which uses amplification to detect the presence of the cfb gene sequence of GBS DNA. We calculated the assay accuracy using sensitivity and specificity.
A total of 233 samples were available. Both the culture and PCR methods were positive for 59 and negative for 157 patients. The culture method was positive and PCR was negative in 9 patients. The culture was negative and the PCR positive for 8 patients. The sensitivity of the PCR assay was 86.8% and specificity was 95.2%. The positive predictive value was 88.1% and the negative predictive value was 94.6%.
Although a rapid PCR assay may be useful to determine GBS status in the urgent intrapartum setting, the false-negative rate of 13.2% for the real-time PCR assay prohibits its use for standard GBS screening in the office.
对携带B族链球菌（GBS）的分娩妇女进行抗生素预防取决于携带者的识别。我们试图使用更严格的培养方法评估实时聚合酶链反应（PCR）检测GBS的诊断准确性。
同时使用两根拭子从同意参与的妇女中获取直肠阴道GBS样本。一根拭子采用经过验证的严格培养技术进行分析，该技术包括直接接种到选择性琼脂上和接种选择性肉汤。另一根拭子用于商业实时PCR检测，该检测通过扩增来检测GBS DNA的cfb基因序列的存在。我们使用敏感性和特异性计算检测准确性。
共有233个样本可用。培养和PCR方法对59例患者均呈阳性，对157例患者均呈阴性。培养方法呈阳性而PCR呈阴性的有9例患者。培养呈阴性而PCR呈阳性的有8例患者。PCR检测的敏感性为86.8%，特异性为95.2%。阳性预测值为88.1%，阴性预测值为94.6%。
尽管快速PCR检测可能有助于在紧急分娩情况下确定GBS状态，但实时PCR检测13.2%的假阴性率使其不能用于门诊的标准GBS筛查。
