Group B Streptococcal Infection During Pregnancy Increases Risk for Poor Neonatal Outcomes

Among women with group B streptococcal (GBS) infections who were pregnant, most had intra-amniotic infections and increased rates of obstetric and neonatal complications. These findings were published in the Journal of Infectious Diseases.

All GBS invasive infections (N=336) among women of childbearing age reported to the French National Reference Center for Streptococci between 2012 and 2020 were analyzed for this study. Infections were categorized as either antepartum (n=57), intrapartum (n=88), postpartum up to 42 days after birth (n=37), unknown stage of pregnancy (n=60), or unrelated with pregnancy (n=94). The researchers assessed the characteristics for each infection, as well as obstetric and neonatal outcomes.

Among a total of 336 women included in the analysis, 242 (72.0%) had a GBS infection related to pregnancy and 94 (28.0%) had an infection unrelated to pregnancy. Of women with pregnancy- and non-pregnancy associated infections, the median age was 32 (range, 19-50) and 40 (range, 19-50) years (P <.0001), 29.1% and 83.3% had at least 1 underlying condition (P <.0001), 67.2% and 16.7% had complications related to infection (P <.0001), and 1.8% and 10.3% died (P =.004), respectively.

After stratification by pregnancy stage, no baseline differences were observed between the 2 groups. Among women with pregnancy-associated GBS infections, the majority (55.8%) had an infection categorized as intra-amniotic and 35.1% had an infection caused by bacteremia without focus.

Neonatal outcomes of GBS infection included death in utero (29.5%), preterm birth (12.6%), and neonatal infection (36.1%). The researchers found that the number of neonatal deaths that occurred in utero were increased among women with GBS infections categorized as antepartum vs those with intrapartum infections (65.4% vs 12.7%). Although an increased rate of preterm birth was observed among women with infections that occurred intrapartum vs those that occurred antepartum (19.2% vs 20.6%), neonatal infections were decreased among those with antepartum infections (26.9% vs 55.6%).

Of women with nonpregnancy-associated GBS infection, there was an increased risk for GBS type Ib (odds ratio [OR], 3.42; 95% CI, 1.44-8.42). On analysis of women with pregnancy-associated GBS infections, the risk for hypervirulent CC-17 GBS isolates was increased in those with an intrapartum infection (OR, 5.08; 95% CI, 1.64-19.33) and decreased among those with a postpartum infection (OR, 0.21; 95% CI, 0.05-0.89).

All GBS isolates were susceptible to amoxicillin, penicillin, and vancomycin. In addition 89.6% of GBS isolates were resistant to tetracycline, with significant resistance to gentamicin observed in 1.2%.

This study may be limited by a lack of generalizability, as GBS reporting to the National Reference Center was voluntary and may be biased toward severe cases.

According to the researchers, “…this work emphasizes the need for developing new strategies, including vaccination during pregnancy, [aimed] at [decreasing] the burden of GBS disease in pregnant women and neonates.”

Reference

Plainvert C, Salvy-Tabet YdS, Dmytruk N, Frigo A, Poyart C, Tazi A. Group B Streptococcus invasive infections in women of childbearing age, France, 2012 – 2020 : GBS CC-17 hypervirulence in intrapartum infections. J Infect Dis. Published online March 5, 2022. doi:10.1093/infdis/jiac076