Ciprofloxacin-Resistant Salmonella enterica Serovar Kentucky in Canada

Michael R. Mulvey

, David A. Boyd, Rita Finley, Ken Fakharuddin, Stacie Langner, Vanessa Allen, Lei Ang, Sadjia Bekal, Sameh El Bailey, David Haldane, Linda Hoang, Greg Horsman, Marie Louis, Lourens Robberts, and John Wylie

Author affiliations: Public Health Agency of Canada, Winnipeg, Manitoba, Canada (M. R. Mulvey, D. A. Boyd, K. Fakharuddin, S. Langner); Public Health Agency of Canada, Guelph, Ontario, Canada (R. Finley); Ontario Agency for Health Protection and Promotion, Toronto, Ontario, Canada (V. Allen); Queen Elizabeth Hospital, Charlottetown, Prince Edward Island, Canada (L. Ang); Institut National de Santé Publique du Quebec, Montreal, Quebec, Canada (S. Bekal); Saint John Regional Hospital, Saint John, New Brunswick, Canada (S. El Bailey); Provincial Public Health Laboratory Network of Nova Scotia, Halifax, Nova Scotia, Canada (D. Haldane); British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada (L. Hoang); Saskatchewan Disease Control Laboratory, Regina, Saskatchewan, Canada (G. Horsman); Alberta Provincial Laboratory for Public Health, Calgary, Alberta, Canada (M. Louis); Newfoundland Public Health Laboratory, St. John’s, Newfoundland, Canada (L. Robberts); Cadham Provincial Laboratory, Winnipeg, Manitoba (J. Wylie)

Abstract

We report emergence of ciprofloxacin-resistant Salmonella enterica serovar Kentucky in Canada during 2003–2009. All isolates had similar macrorestriction patterns and were multilocus sequence type ST198, which has been observed in Europe and Africa. Ciprofloxacin-resistant S. enterica serovar Kentucky represents 66% of all ciprofloxacin-resistant nontyphoidal Salmonella sp. isolates observed in Canada since 2003.

Infections with Salmonella spp. are a major health concern for humans and animals on a global scale. Although most cases of salmonellosis result in uncomplicated diarrhea, elderly and immunocompromised persons can be at risk for more severe invasive infections, which can be life-threatening and may require antimicrobial drug therapy (1). The drugs of choice for treating these invasive infections are fluoroquinolones (for adults) or cephalosporins.
One of the main drivers of antimicrobial drug resistance in Salmonella spp. is use of antimicrobial drugs in food-producing animals. For example, high rates of cephalosporin resistance in Salmonella enterica serovar Heidelberg isolated from poultry, retail chicken meat, and humans were observed in Quebec, Canada in 2003. After a voluntary withdrawal of cephalosporins was instituted by the Quebec broiler industry in 2005, rates of ceftiofur resistance dramatically decreased in animals and humans (2).
As with cephalosporin resistance, ciprofloxacin resistance in Salmonella spp. is a growing concern. Recently, S. enterica serovar Kentucky isolates have been described in Europe and Africa that were ciprofloxacin resistant (3). In addition, these isolates were resistant to multiple classes of antimicrobial drugs, which further complicates treatment options for invasive disease. No S. enterica serovar Kentucky isolates submitted to the National Antimicrobial Resistance Monitoring System in the United States were ciprofloxacin resistant (3). The purpose of this study was to describe the epidemiology and characterize isolates of ciprofloxacin-resistant S. enterica serovar Kentucky identified in Canada.

The Study

The Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS), established in 2003, monitors antimicrobial drug use and resistance in selected species of enteric bacteria from humans, animals, and animal-derived food sources across Canada (www.phac-aspc.gc.ca/ cipars-picra/surv-eng.php). Human Salmonella isolates were submitted by all provincial public health laboratories in Canada to the National Microbiology Laboratory for further characterization. Antimicrobial drug susceptibility testing was performed by using broth microdilution (Sensititer Automated Microbiology System; Trek Diagnostic Systems Ltd., Westlake, OH, USA) and breakpoints established by the Clinical Laboratory Standards Institute (4).