An outbreak of Carbapenemase-producing Enterobactericeae in a Neonatal Intensive Care Unit, NSW, Australia

Ms Sally Munnoch1, Mr Jeffrey Deane1, Dr Hemalatha Varadhan2, Dr Rodney  Givney2, Professor Jon Iredell3,4, Dr  Nouri Ben Zakour3, Dr Joanne McIntosh1, Dr John  Ferguson1

1Hunter New England Local Health District, New Lambton Heights, Australia
2NSW Health Pathology, New Lambton Heights, Australia
3Westmead Institute for Medical Research, Westmead, Australia
4The University of Sydney, Westmead, Australia


Introduction: The emergence of carbapenemase producing Enterobacteriaceae (CPE) represents an important and increasing threat to patients in acute care settings. In January 2018, we identified a small cluster of patients with Klebsiella pneumoniae, from the Neonatal Intensive Care Unit (NICU) in a large tertiary hospital in NSW. The presence of meropenem resistance in prompted molecular analysis by PCR which confirmed the presence of a blaIMP4 carbapenemase gene in patient isolates.

Methods: Identification of the outbreak prompted an epidemiological investigation into the possible risk factors associated with infection/colonisation, implementation of infection control, environmental sampling and additional patient screening. Whole genome sequencing (WGS) of isolates from this and a smaller CPE outbreak occurring in patients from the same unit in early 2017 was conducted.

Results: Seven patients were associated with the 2018 cluster, sharing two multi-crib rooms. WGS was successfully conducted on five isolates with four carrying an identical sequence type (ST26-1LV). Although isolates from the 2018 were distinct to the 2017 batch (different ST types), plasmid analysis indicate the isolates are genomically similar.  Environmental swabbing post enhanced cleaning did not identify an environmental source. Our microbiological and epidemiological investigations continue.

Conclusion: Our investigation emphasises the importance of early identification of patients with CPE and the timely use of WGS to identify plasmid transmission in the acute care setting. Microbiological analysis indicates that isolates from both clusters contain unique but clonal isolates, however an environmental source remains unidentified. An update on our formal epidemiological investigation and molecular analysis will be provided.


Sally Munnoch is the Infection Prevention Service Epidemiologist at Hunter New England Local Health District.

She has a strong interest in hospital epidemiology, outbreak management and control, and exploring novel methods for disease surveillance.

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