Background: How best to target intrapartum antibiotic prophylaxis (IAP) to minimise both Early-Onset Group B Streptococcus (EOGBS) neonatal infection and maternal/fetal antibiotic exposure is uncertain, with both routine-screening and risk-factor approaches available.
Aims: This retrospective cohort study was undertaken to examine the outcomes of a hybrid risk-and-screen approach to EOGBS prevention using GBS polymerase chain reaction (PCR). The target population was women with term prelabour rupture of membranes (TermPROM) having the risk factor of prolonged rupture of membranes (ROM) ≥18 h.
Materials and methods: Non-labouring TermPROM women had rapid GBS PCR testing at presentation. GBS screen-positive women proceeded to induction of labour and received IAP. GBS screen-negative women were allowed home to await spontaneous labour and not given IAP regardless of duration of ROM, unless other risk factors developed. For all other women, the risk-factor approach was followed.
Results: From 2009 to 2018, there were 20 cases of culture-positive EOGBS, a rate of 0.36/1000 live births (95% CI 0.22-0.56/1000), comparable to other recent reports. Over 2010-2018 when laboratory data were available, 1120 TermPROM women with ROM ≥18 h avoided antibiotics because they were GBS PCR-negative (2.3% of all births, 3.6% of vaginal births) while 338 TermPROM women with ROM <18 h received targeted antibiotics for being GBS-positive. No cases of EOGBS occurred in TermPROM women, those with ROM ≥18 h, or due to protocol-compliance failure.
Conclusions: A hybrid approach involving risk-factor-based IAP and intrapartum GBS PCR screening of non-labouring TermPROM women delivers acceptably low rates of EOGBS while minimising and better targeting antibiotic exposure.
Keywords: PCR; antibiotic prophylaxis; group B streptococcal infection; term premature rupture of fetal membranes.
© 2020 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.