“Down the drain”: carbapenem-resistant bacteria in intensive care unit patients and handwashing sinks

Despina Kotsanas, W R P L I Wijesooriya, Tony M Korman, Elizabeth E Gillespie, Louise Wright, Kylie Snook, Natalie Williams, Jan M Bell, Hua Y Li and Rhonda L Stuart
Med J Aust 2013; 198 (5): 267-269. || doi: 10.5694/mja12.11757


Objectives: Clinical utility of carbapenem antibiotics is under threat because of the emergence of acquired metallo-β-lactamase (MBL) genes. We describe an outbreak in an intensive care unit (ICU) possibly associated with contaminated sinks.

Design, setting and participants: Four clusters of gram-negative bacteria harbouring the MBL gene blaIMP-4 were detected in the ICU at Dandenong Hospital between November 2009 and July 2012. Epidemiological investigations were undertaken in order to identify a common point source. During September 2012, screening using rectal swabs for all ICU patients, and environmental swabs targeting all ICU handwashing sinks and taps were collected. Samples were cultured onto selective carbapenem-resistant Enterobacteriaceae (CRE) agar. Suspected CRE isolates were further characterised using the modified Hodge test and VITEK 2 and confirmed by polymerase chain reaction and sequencing of MBL genes. Clinical and environmental CRE isolates were typed by pulsed-field gel electrophoresis.

Results: Ten clinical isolates and one screening isolate of CRE (consisting of Klebsiella pneumoniae [5], Serratia marcescens [4], Enterobacter cloacae [1] and Escherichia coli [1]) were detected with the blaIMP-4 gene over the 30-month period. S. marcescens was isolated persistently from the grating and drain of eight central sinks. Molecular typing confirmed that clinical and environmental isolates were related. Tap water cultures were negative. Several attempts to clean and decontaminate the sinks using detergents and steam cleaning proved unsuccessful.

Conclusion: This report highlights the importance of identification of potential environmental reservoirs, such as sinks, for control of outbreaks of environmentally hardy multiresistant organisms.

  • Despina Kotsanas1
  • W R P L I Wijesooriya1
  • Tony M Korman1
  • Elizabeth E Gillespie2
  • Louise Wright2
  • Kylie Snook2
  • Natalie Williams2
  • Jan M Bell3
  • Hua Y Li4
  • Rhonda L Stuart1,5

  • 1 Monash Infectious Diseases, Southern Health, Melbourne, VIC.
  • 2 Infection Control and Epidemiology, Southern Health, Melbourne, VIC.
  • 3 Microbiology and Infectious Diseases, Women’s and Children’s Hospital, Adelaide, SA.
  • 4 Microbiological Diagnostic Unit, University of Melbourne, Melbourne, VIC.
  • 5 Department of Medicine, Southern Clinical School, Monash University, Melbourne, VIC.

Competing interests:

No relevant disclosures.

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