A novel one-step real-time multiplex PCR assay to detect Streptococcus agalactiae presence and serotypes Ia, Ib, and III

Diagn Microbiol Infect Dis. 2017 Sep;89(1):7-12. doi: 10.1016/j.diagmicrobio.2017.06.003. Epub 2017 Jun 16.

Abstract

Streptococcus agalactiae is the leading cause of early-onset neonatal sepsis. Culture-based screening methods lack the sensitivity of molecular assays and do not indicate serotype; a potentially important virulence marker. We aimed to develop a multiplex PCR to detect S. agalactiae while simultaneously identifying serotypes Ia, Ib, and III; commonly associated with infant disease. Primers were designed to target S. agalactiae serotype-specific cps genes and the dltS gene. The assay was validated with 512 vaginal specimens from pregnant women. 112 (21.9%) were dltS positive, with 14.3%, 0.9%, and 6.3% of these identified as cps Ia, Ib, and III, respectively. Our assay is a specific and sensitive method to simultaneously detect S. agalactiae and serotypes Ia, Ib, and III in a single step. It is of high significance for clinical diagnostic applications and also provides epidemiological data on serotype, information that may be important for vaccine development and other targeted non-antibiotic therapies.

Keywords: Capsular polysaccharide; Early-onset sepsis; Group B streptococcus; Real-time PCR; Serotypes; Streptococcus agalactiae.

Publication types

  • Validation Study

MeSH terms

  • DNA Primers / genetics
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Multiplex Polymerase Chain Reaction / methods*
  • Neonatal Sepsis / diagnosis*
  • Neonatal Sepsis / microbiology
  • Pregnancy
  • Real-Time Polymerase Chain Reaction / methods*
  • Retrospective Studies
  • Sensitivity and Specificity
  • Serogroup*
  • Streptococcal Infections / diagnosis*
  • Streptococcal Infections / microbiology
  • Streptococcus agalactiae / classification
  • Streptococcus agalactiae / genetics
  • Streptococcus agalactiae / isolation & purification*

Substances

  • DNA Primers