Outbreak of Carbapenem-Resistant Enterobacteriaceae Containing blaNDM-1, Ontario, Canada

Background. New Delhi metallo-beta-lactamase (NDM) has emerged worldwide in clinically relevant gram-negative bacteria. We report an outbreak of NDM-producing Klebsiella pneumoniae in patients with no prior travel history to endemic regions. Methods. Five NDM-1-producing K. pneumoniae colonizing and/or clinically infecting patients in a community tertiary hospital were detected between October and November 2011. NDM-1-producing Enterobacteriaceae (K. pneumoniae and Escherichia coli) were clinically and epidemiologically characterized, including susceptibility profiles, molecular typing, and molecular characterization of plasmids and resistant determinants. Results. Five patients were identified carrying NDM-1-producing K. pneumoniae, all of them epidemiologically linked with each other. K. pneumoniae were confirmed to belong to the same clone, exhibiting multidrug-resistant phenotypes. One patient was positive for NDM-1-producing E. coli in blood and E. coli and K. pneumoniae in rectal specimens, both containing the same bla(NDM) plasmid, suggesting horizontal transfer between species in the patient. No environmental sources of these strains were found. Detection of positive isolates directly from rectal specimens allowed the rapid identification and isolation of colonized patients. Conclusions. We report a NDM-1-producing K. pneumoniae outbreak in Ontario, Canada. Implementation of standard infection control practices, including active screening was able to contain the spread of this organism in the hospital setting. Of concern is the potential loss of a travel history to identify patients that are at high risk of being colonized or infected with this organism and the lack of an accurate, cost-effective test that can be implemented in the hospital setting to identify these multidrug-resistant organisms.