OBJECTIVES: There are limited data on Enterobacter cloacae outbreaks and fewer describing these in association with NDM-1. With whole-genome sequencing, we tested the hypothesis that a cluster of 16 E. cloacae bacteraemia cases in a Nepali neonatal unit represented a single clonal outbreak, using a wider set of epidemiologically unrelated clinical E. cloacae isolates for comparison. METHODS: Forty-three isolates were analysed, including 23 E. cloacae and 3 Citrobacter sp. isolates obtained from blood cultures from 16 neonates over a 3 month period. These were compared with two contemporaneous community-associated drug-resistant isolates from adults, a unit soap dispenser isolate and a set of historical invasive isolates (n=14) from the same geographical locality. RESULTS: There were two clear neonatal outbreaks and one isolated case in the unit. One outbreak was associated with an NDM-1 plasmid also identified in a historical community-associated strain. The smaller, second outbreak was likely associated with a contaminated soap dispenser. The two community-acquired adult cases and three sets of historical hospital-associated neonatal isolates represented four additional genetic clusters. CONCLUSIONS: E. cloacae infections in this context represent several different transmission networks, operating at the community/hospital and host strain/plasmid levels. Wide sampling frames and high-resolution typing methods are needed to describe the complex molecular epidemiology of E. cloacae outbreaks, which is not appropriately reflected by routine susceptibility phenotypes. Soap dispensers may represent a reservoir for E. cloacae and bacterial strains and plasmids may persist in hospitals and in the community for long periods, sporadically being involved in outbreaks of disease.

Original publication

DOI

10.1093/jac/dku521

Type

Journal article

Journal

J Antimicrob Chemother

Publication Date

04/2015

Volume

70

Pages

1008 - 1015

Keywords

NDM, carbapenemases, epidemiology, whole-genome sequencing, Adult, Bacteremia, Blood, Cluster Analysis, DNA, Bacterial, Disease Outbreaks, Disease Transmission, Infectious, Enterobacter cloacae, Enterobacteriaceae Infections, Environmental Microbiology, Genome, Bacterial, Genotype, High-Throughput Nucleotide Sequencing, Humans, Infant, Newborn, Intensive Care Units, Neonatal, Molecular Epidemiology, Molecular Sequence Data, Nepal, Retrospective Studies