Maternal Colonization With Extended-spectrum Beta-lactamase-producing Enterobacteriaceae and Vertical Transmission...

Preterm infants are at high risk of morbidity and mortality, with early-onset neonatal sepsis (EOS) being a major concern. Antimicrobial resistance from extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) further complicates treatment. This study aimed to evaluate maternal ESBL-E colonization, vertical transmission and associated neonatal outcomes.

A prospective cohort study was conducted between October 2023 and November 2024 at Ramathibodi Hospital, Bangkok, Thailand. Pregnant women <37 weeks' gestation admitted with preterm labor or preterm prelabor rupture of membranes were screened for vaginal ESBL-E colonization at admission, with repeat swabs if hospitalization exceeded 72 hours. Neonatal surface cultures were obtained at birth. Maternal risk factors and neonatal outcomes were compared between colonized and noncolonized groups.

Among 155 deliveries, 6.4% (10/155) of mothers were colonized with ESBL-E, with a vertical transmission rate of 20% (2/10). Risk factors included cervical cerclage or pessary placement (20% vs. 2.1%, P = 0.03) and prior Group B Streptococcus (GBS) colonization (40% vs. 11%, P = 0.03). Infants born to colonized mothers had earlier gestational age (33.3 weeks [interquartile range (IQR) 32.9-33.7] vs. 35.3 weeks [IQR 33-36.8]; P = 0.04), higher cesarean delivery rates (100% vs. 59.3%, P = 0.01), lower birth weights (1870 g [IQR 1485-2440] vs. 2360 g [IQR 1900-2780], P = 0.03), and longer hospital stays (17 days [IQR 10-27] vs. 5 days [IQR 3-18], P = 0.01).

Cervical procedures and prior GBS colonization were associated with maternal ESBL-E colonization. Infants born to colonized mothers experienced poorer outcomes, underscoring the need for targeted screening and consideration of broader empiric antibiotic coverage in at-risk preterm infants.