title: Evaluation of an in-house real-time polymerase chain reaction method to identify group B streptococcus colonization in pregnancy.
abstract: OBJECTIVE
  The aim of this study was to evaluate the performance of in-house real-time polymerase chain reaction (qPCR) in detecting group B streptococcus (GBS) colonization compared with the standard culture method in a cohort of pregnant women.
  
  
  METHODS
  A total of 134 rectovaginal swabs were collected from 125 pregnant women, of whom 108 were known carriers or presented with preterm prelabor rupture of membranes. The swabs were placed in Standard Methods Broth (Todd-Hewitt broth supplemented with 6 μg/mL gentamicin and 15 μg/mL nalidixic acid) for culture identification of GBS. An in-house qPCR was also performed from the broth and after overnight incubation of the broth.
  
  
  RESULTS
  The detection rate of GBS in this cohort was 30.6% and 50.7% using standard culture method and qPCR, respectively. GBS-specific qPCR assay gave sensitivities of 97.6% and 100%, specificities of 73.1% and 71.0%, and negative predictive values of 98.6% and 100% from direct specimen and from broth after overnight incubation, respectively.
  
  
  CONCLUSIONS
  The in-house qPCR test has high sensitivity in detecting GBS colonization. The high negative predictive value helps to avoid unnecessary use of antibiotics in uncolonized women.
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Hong Kong, SAR.
authors.forename: Sik-Wing
authors.initials: SW
authors.lastname: Yeung
authors.affiliation: Department of Microbiology, The Chinese University of Hong Kong, Hong Kong, SAR.
authors.forename: Pik-Tsz
authors.initials: PT
authors.lastname: Cheung
authors.affiliation: Department of Microbiology, The Chinese University of Hong Kong, Hong Kong, SAR.
authors.forename: Sze-Lok
authors.initials: SL
authors.lastname: Chau
authors.affiliation: Department of Microbiology, The Chinese University of Hong Kong, Hong Kong, SAR.
authors.forename: Margaret
authors.initials: M
authors.lastname: Ip
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Hong Kong, SAR.
authors.forename: Terence Tzu-Hsi
authors.initials: TT
authors.lastname: Lao
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Hong Kong, SAR.
authors.forename: Tak-Yeung
authors.initials: TY
authors.lastname: Leung
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Hong Kong, SAR.
authors.forename: Wing-Hung
authors.initials: WH
authors.lastname: Tam
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis*; D037841:Pregnant People; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000175:diagnosis*; D013292:Streptococcus agalactiae / Q000302:isolation & purification*
keywords: bacteria colonization; group B streptococcus; neonatal infection; pregnancy and real-time polymerase chain reaction