Background
While many guidelines recommend a 10‐day course of oral erythromycin following preterm prelabour rupture of membranes (PPROM) as derived from the ORACLE I trial, evidence is emerging that this may encourage a state of antenatal genital tract dysbiosis. In addition, erythromycin’s lack of efficacy toward Gram‐negative microorganisms may promote colonisation and infection, conveying more significant unrecognised risk for very and extremely preterm newborns.

Aims
To define patterns of placental infection or colonisation in newborns born before 30 completed weeks gestation following PPROM.

Materials and Methods
Retrospective cohort study of mother‐infant dyads who delivered at < 30 completed weeks gestation following PPROM in a South Australian tertiary perinatal centre between January 2012 and December 2015. Main outcome measures included placental and neonatal culture and sensitivities within 72 h of delivery and histologic chorioamnionitis. Categorical characteristics were analysed using two‐sided Fisher’s exact test and numerical characteristics via analysis of variance. Results During the four years studied, 126 infant‐mother dyads were identified. Where a placental swab was taken, 23.9% cultured Gram‐negative organisms and the majority (58.8%) were antimicrobial‐resistant. Those that received erythromycin had increased incidence of antimicrobial‐resistant Gram‐negative organisms on placental swab (P = 0.02). All cases of neonatal early‐onset sepsis (EOS), including two cases of multi‐resistant Gram‐negative EOS, occurred in those who received erythromycin. Conclusions The current antibiotic recommendations for PPROM may promote selection of unhindered antimicrobial‐resistant Gram‐negative organisms and may increase risk of Gram‐negative EOS in very and extremely preterm newborns. Further wide‐scale examination of antibiotic recommendations in PPROM is necessary.