A new study published in the Journal of Gynecology, Obstetrics and Human Reproduction assessed whether the presence of ampicillin-resistant enterobacteria in the vaginal microbiome is predictive of an increased risk of early-onset neonatal infection in cases with premature rupture of membranes (PROM) occurring at 23-34 weeks gestation (WG). In this prospective, observational, single-center study, conducted at the Nice Academic Hospital maternity ward between March 16, 2014 and May 3, 2015, mothers with preterm PROM (24-34 WG) were evaluated. Subjects were divided into two groups according to the vaginal samples (VS) bacteria isolates and the amoxycillin-resistant enterobacteria found. Two groups were formed for the newborns, depending on the suspicion of perinatal maternal-fetal bacterial infection (MFI). Of the 67 patients included, 12 newborns presented a strong MFI suspicion, 83% of which were associated to the group of patients with untreated or amoxycillin-resistant enterobacteria VS isolates. Thus, the findings indicated that vaginal colonization of untreated or amoxycillin-resistant enterobacteria constitutes a major risk factor of neonatal infection.