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.
Keywords: Gram-negative; antimicrobial resistance; dysbiosis; erythromycin; preterm prelabour rupture of membrane.
© 2019 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.