Intrapartum maternal risks of group B streptococcus carriage in premature rupture of membranes

BACKGROUND: Group B streptococcal infection remains the epicenter of attention for maternal and child health services around the world. Premature rupture of membranes requires adaptation of obstetric tactics and intrapartum antibiotic prophylaxis.

AIM: The aim of this study was to identify maternal intrapartum risks of group B streptococcus colonization of the birth canal and the lack of antepartum screening for group B streptococcus in cases of premature rupture of membranes in full-term pregnancy.

MATERIALS AND METHODS: This retrospective cohort study was conducted in the Perinatal Center of City Clinical Hospital No. 31 named after Academician G.M. Savelyeva (Moscow, Russia) in 2023–2024. We selected women with premature rupture of membranes at full-term pregnancy, whose birth canals were subsequently divided into those colonized by group B streptococcus and those not colonized and who underwent antenatal group B streptococcus screening at 35–37 weeks of pregnancy or not. In the absence of group B streptococcus screening upon admission to the hospital, vaginal discharge was collected and sent off for bacteriological testing. Two tactics for labor management were selected: expectant, and active. Intrapartum antibiotic prophylaxis was performed in case of group B streptococcus isolation during screening.

RESULTS: With premature rupture of membranes in full-term pregnancy, only 57.14% of group B streptococcus carriers have prenatal group B streptococcus screening; therefore, in 42.86% of group B streptococcus carriers, intrapartum antibiotic prophylaxis was delayed by 18 hours. Group B streptococcus carriage is not associated with the gestational age of premature rupture of membranes, but has intrapartum features such as a trend of younger age (less than 30 years) and attendance at the hospital earlier than six hours after premature rupture of membranes with the opportunity for induction or effective pre-induction of labor with a single dose of an antigestagen (in more than 70% of women). These women had a blood leukocyte count of ≥12.5 × 10⁹/l and higher C-reactive protein levels. They were most often delivered by cesarean section, with characteristic indications for chorioamnionitis and fetal distress. The absence of prenatal group B streptococcus screening distinguishes the age of women under 30 years old, the threshold C-reactive protein level being 19.5 g/l, with a tendency towards a less frequent spontaneous onset of labor and a higher frequency of its induction, hypotonic hemorrhage, and chorioamnionitis.

CONCLUSIONS: There are intrapartum maternal risks of group B streptococcus carriage and the presence of group B streptococcus screening, which are conditionally controlled in the Moscow. Intrapartum antibiotic prophylaxis and the metropolis resource “equalize” the outcome of births in cases of group B streptococcus carriage and absence, with the presence and absence of group B streptococcus screening. Modern medicine allows for minimizing the risks of chorioamnionitis and hypotonic hemorrhage in group B streptococcus carriers after premature rupture of membranes, even in the absence of group B streptococcus screening in more than half of women or deferment of intrapartum antibiotic prophylaxis for 18 hours.