Delineating the risk factors, sources of acquisition and clinical outcomes in neonates colonised with multidrug-resistant bacteria: the NeoCol study

Antimicrobial resistance contributes to neonatal mortality globally. Delineating transmission pathways resulting in neonatal colonisation with multidrug-resistant (MDR) bacteria is necessary to reduce this burden. We conducted a prospective cohort study of 189 mother-infant dyads to identify the risk factors associated with transmission of MDR bacteria, revealing a high prevalence of maternal colonisation with MDR bacteria at delivery (63%, 120/189), and in neonates by hospital discharge (61%, 115/189). However, maternal colonisation with carbapenem-resistant Enterobacterales (CRE) was low (3%, 6/189) whereas CRE acquisition occurred at a median time point of 13 days in hospitalised neonates (26%, 50/189), suggesting horizontal transmission of CRE predominates. Compared to non-colonised neonates, those colonised with MDR bacteria were more likely to have been exposed to antibiotics prior to colonisation (63%, vs 24%, p < 0.001), require a longer hospital stay (16 days vs 2 days, p < 0.001) and have episodes of sepsis following colonisation (62% vs 24%, p < 0.001). However, most culture-positive neonatal infections (91%, 10/11) were not caused by previously identified colonising bacteria. Our study reveals poor clinical outcomes associated with MDR neonatal colonisation, and suggests improved antibiotic stewardship strategies may reduce this burden.