ESBL K. oxytoca outbreak in a Special Care Nursery: investigation, control and the utility of real-time Whole Genome Sequencing

Dr. Paul Chapman1,2, Debra Vesey1, Haakon Berge3, Dr. Amy Jennison3, Dr Patrick Harris3,4, Leah Roberts5, Dr.  Brian Forde5, Associate Professor Scott Beatson5

1Caboolture Hospital, Caboolture, Australia

2QIMR-Berghofer, Herston, Australia

3Pathology Queensland, Herston, Australia

4UQCCR, Herston, Australia, 5School of Chemistry and Molecular Biosciences, UQ, St. Lucia, Australia



The investigation into an outbreak of extended spectrum beta-lactamase (ESBL) producing Klebsiella oxytoca in a special care nursery (SCN) revealed contaminated washing detergent as the source.  Here we detail the investigation, management and elimination of this outbreak.


Patients in SCN with ESBL K. oxytoca cultured from any source were defined as cases.  Occupants of SCN were screened for multi-resistant gram negatives (MRGN) every 48 hours.  Extensive environmental sampling was performed.  Observation of infection control procedures and policy compliance was performed.  Whole genome sequencing (WGS) was performed on all isolates of K. oxytoca.


There were ten cases of K. oxytoca colonisation with no clinical infections.  The outbreak lasted 203 days. Extensive environmental sampling of SCN failed to reveal a source.  Sampling was therefore extended to maternity and birthsuite areas.   A drain and later detergent in a multi-purpose room were found to harbour the ESBL K. oxytoca.  7 of 12 sampled hospital detergent bottles were also positive.  WGS confirmed a novel sequence type (ST) and minimal genetic distance between cases and detergent suggesting the independent colonisation of each patient from an environmental source rather than patient-to-patient.  Isolates from Case 2, 10 and detergent from SCN were identical at core-genome level.  7 of 10 mothers were contactable, of which 6 reported using detergent to wash breast-expressing equipment.


Contamination of detergent resulted in colonisation of 10 patients with ESBL K. oxytoca.  The control of the outbreak required intensive infection control investigation.  Real-time WGS confirmed the source and likely transmission characteristics.


Debra is a dedicated Infection Control and Prevention CNC at Caboolture hospital.

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