Group B Streptococcus Screen - Provincial

Microbiology

Overview

Group B Streptococcus (GBS; Streptococcus agalactiae) commonly colonizes the vagina and rectum. During labor and delivery, if this organism is transmitted to the newborn it can cause serious invasive disease such as sepsis or meningitis. Screening for GBS colonization is recommended between 35 and 37 weeks of pregnancy to inform whether intrapartum antibiotics should be provided to reduce the risk of transmitting GBS to the infant.
All pregnant individuals should have GBS screening performed between 35 and 37 weeks

Insert swab approximately 2-3 cm into vagina, rotate to ensure uniform swab coverage of sample
Insert the same swab 1-3 cm into the anus, gently rotate to sample anal crypts

Swab specimens in Eswab® transport media can be transported at room temperature or refrigerated at 4°C

GBS is universally susceptible to beta-lactam antibiotics, including penicillin and cephalosporins. Routine susceptibility testing is not performed.
Patients with severe drug allergies that cannot receive treatment with beta-lactam antibiotics should have clindamycin susceptibility testing requested on positive GBS screen isolates. Clindamycin susceptibility is variable.
GBS is also universally susceptible to vancomycin, which in the absence of susceptibility testing can be used reliably in beta-lactam allergic patients.

RGH/Pasqua	Specimens are retained for 7 days after initial processing
Saskatoon	Specimens are retained for 3 days after initial processing.

Last Updated: May 27, 2025