Strep B PCR – GFH (Antenatal Screening)

Molecular Test for Group B Strep from Vaginal/Rectal Specimens


Useful For

The Cepheid GBS LB  assay is a qualitative in vitro diagnostic test for detection of Group B Streptococcus in either LIM broth cultures of vaginal/rectal swabs from antepartum women following 18 to 24 hours of incubation.

The Cepheid GBS LB Assay does not provide susceptibility results.  Culture isolates are needed for performing susceptibility testing as recommended for penicillin-allergic women.

Screening for GBS colonization in antepartum women (between 35 and 37 weeks’ gestation), is one of the key components of the CDC’s GBS screening strategy and is an effective mechanism for prevention of perinatal Group B Streptococcal disease. As colonization may be transient, intermittent or persistent throughout pregnancy, screening is most effective when performed when specimens are collected no more than five weeks (35 to 37 weeks’ gestation) prior to delivery and after enrichment with selective broth medium.

Method Name

PCR Assay



Specimen Type

  • Vaginal/rectal swab specimens from antepartum women for enrichment broth culture should be collected, stored, and handled according to the CDC recommended clinical procedure.

Specimen Required

E-Swab of Vaginal/Rectal area

Specimen Minimum Volume

1 E-swab

Specimen Stability Information

  • Must be collected in an E-Swab.
  • Room Temperature E-swabs are stable for 48 hours
  • Refrigerated E-swab specimens are stable for up to 5 days.
  • Transport at Room temperature

Rejected Due To

  • Specimen not collected in an E-Swab.
  • Room Temperature E-swabs received after 48 hours
  • Refrigerated E-swab specimens received after 5 days.
  • Specimen not transported at Room temperature

Performing Laboratory

Glens Falls Hospital Microbiology Laboratory

Reference Values


Day(s) and Time(s) Performed

  • Day Shift
  • 7 days per week

Analytical Time

1x daily

Specimen Retention Time

7 days for positive specimens

Analytical Time

1x daily