Colistin use in a carbapenem-resistant Enterobacterales outbreak at a South African neonatal unit

Background: Colistin is increasingly prescribed for neonates with carbapenem-resistant Enterobacterales (CRE) infections. Objectives: We described patient demographics, infection episodes, treatment and clinical outcomes, colistin related adverse events and relatedness of isolates in neonates with clinically confirmed or clinically suspected CRE infections. Method: The authors retrospectively reviewed culture-confirmed and clinically suspected culture-negative CRE infections at a South African neonatal unit during a CRE outbreak. Results: Fifty-three neonates (median gestational age 29 weeks and birth weight 1185 g) were included. Twenty-three of 53 neonates (43%) had culture-confirmed CRE (17 received colistin; 6 died without receiving colistin) and 30 (57%) received colistin for clinically suspected CRE infection but were ultimately culture-negative. Prior respiratory support and surgical conditions were present in 37/53 (70%) and 19/53 (36%) neonates, respectively. Crude mortality was high (20/53; 38%) with no significant difference between culture-confirmed CRE versus clinically suspected culture-negative CRE groups (10/23 [44%] vs 10/30 [33%]; p = 0.45). Hypomagnesaemia (10/38; 26%) and hypokalaemia (15/38; 40%) were frequent; acute kidney injury was rare (1/44; 2%). Three CRE infection clusters were identified by genotypic analysis of 20 available isolates (18 [90%] blaNDM-1 [New Delhi metallo-beta-lactamase], 2 [10%] blaOXA [oxacillinase]-48). Conclusion: Neonates receiving colistin therapy were predominantly preterm, with multiple risk factors for infection. Colistin-associated electrolyte derangement was frequent. Over one-third of neonates died. BlaNDM-1 was the most frequent carbapenemase gene identified in the outbreak isolates. Contribution: Colistin was safely used during an Enterobacterales outbreak in predominantly premature and surgical neonates. The mortality was high.