Taking a Proactive Approach to Group B Streptococcus (GBS) Screening for Perinatal Care

Group B Streptococcus is a bacterium that commonly colonizes the gastrointestinal tract and is part of the vaginal microbiome in some women³. While often asymptomatic, GBS can lead to invasive disease in pregnant women and is a leading cause of severe neonatal disease³.

Risks associated with GBS carriage include:

• For pregnant women: Urinary tract infections, amnionitis, endometritis, and tragically, miscarriages, stillbirths, and preterm deliveries⁴.
• For newborns: GBS is the most common cause of bacteremia, sepsis, pneumonia, and meningitis⁴.

According to the WHO, about 1 in 5 pregnant women worldwide carry or are colonized with group B strep⁵. Approximately 50% of these colonized women will transmit the bacteria to their newborns⁴. Without intrapartum antibiotic prophylaxis (IAP), 1–2% of those newborns will develop GBS Early-Onset Disease (EOD)⁴. Alarmingly, rates of mortality and morbidity related to GBS EOD are markedly higher among preterm newborns, with mortality rates of 19.2% compared to 2.1% in term newborns⁴.

Current prevention strategies for GBS involve screening pregnant women and administering IAP, primarily using beta-lactam antibiotics like penicillin and ampicillin⁴. This empiric therapy is based on the assumption that GBS is susceptible to these drugs⁴.

However, the WHO is now reporting increasing resistance rates to penicillin and beta-lactams in general¹. This highlights the growing need for antimicrobial susceptibility testing and monitoring.

In many countries, a standard of care for all pregnant women is to be routinely tested for GBS with a vaginal/rectal swab test during the 36th or 37th week of each pregnancy unless their urine already cultured positive in the current pregnancy⁶.