August 23rd, 2019

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Intrapartum Polymerase Chain Reaction Testing for Maternal Group B Streptococcus Status
Authors:  Susanne M. Matias-Gomes, D.O., Jamil T. Elfarra, M.D., Alfredo DelaGuardia, M.D., Hani M. Tamim, Ph.D., and Paul D. Bobby, M.D.
  OBJECTIVE: To compare the efficacy of intrapartum culture to polymerase chain reaction (PCR) assay for detection of group B streptococcus (GBS).

STUDY DESIGN: Patients presenting to Stamford Hospital after 37 completed weeks of gestation for delivery were eligible to participate if antenatal GBS culture results were documented. Following informed consent, all participants at admission underwent rectal-vaginal sampling to culture for GBS using selective media and to undertake PCR analysis using the Cepheid ID platform. The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values of both GBS detection techniques were compared.

RESULTS: A total of 142 patients completed the study protocol; 3 samples were not resulted due to lab error, so those patients were excluded. Intrapartum GBS culture results were considered the gold standard; 26 (19%) of them were positive. The sensitivity, specificity, PPV, and NPV of antenatal culture were 80%, 95%, 77%, and 96%, respectively. The sensitivity, specificity, PPV, and NPV of intrapartum PCR were 92%, 94%, 77%, and 98%, respectively.

CONCLUSION: Intrapartum PCR–based screening for maternal GBS colonization and intrapartum cultures demonstrate similar sensitivity, specificity, and predictive value. Rapid PCR testing appears to be a reasonable substitute for traditional cultures in patients who present in labor without available
antepartum GBS test results.
Keywords:  polymerase chain reaction, streptococcus, streptococcus group B, streptococcal infections
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