Characterization of antimicrobial resistance among canine urinary isolates in Western Canada
Date
2019-07-17
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
Background: Urinary tract infections (UTIs) are common in veterinary medicine. Escherichia coli (E. coli) and Staphylococcus pseudintermedius (S. pseudintermedius) are the two most common causes of canine UTIs. The emergence of resistance to first line antimicrobials in these pathogens has posed challenges for veterinarians to treat their patients. Surveillance to detect the emergence of antimicrobial resistance (AMR) in companion animal pathogens is lacking in Western Canada. The efficacy of alternative agents for treating canine UTIs is similarly under investigated. The objective of this study was to determine the frequency and characterize the mechanisms of AMR among canine urinary pathogens in Saskatoon, Canada.
Methods: Non duplicate canine urinary isolates (516 E. coli and 113 S. pseudintermedius) were collected from a diagnostic laboratory between November 1st, 2014 and October 31st, 2018. Susceptibility testing was performed by agar dilution or broth microdilution against 15 antimicrobials belonging to 8 different drug classes and interpreted according to published breakpoints. Molecular characterization of resistance was performed by polymerase chain reaction (PCR) and epidemiological relationships were assessed by multi-locus sequence typing (MLST).
Results: A substantial majority of isolates were susceptible to all antimicrobials tested. There was no significant increase in the frequency of resistance to any of the tested agents during the study period. Among E. coli, resistance to ampicillin was most common. Seven E. coli and four S. pseudintermedius were fosfomycin resistant. Overall, twelve isolates harbored CMY-2 type AmpC -lactamases, and seven produced CTX-M type extended spectrum -lactamases (ESBLs). Of the fosfomycin resistant E. coli, one also possessed an CMY-2 type AmpC -lactamase. Of the fosfomycin resistant S. pseudintermedius, three were methicillin resistant. One isolate produced the aac(6′)- Ib-cr gene. A single isolate belonging to the pandemic lineage ST131 was identified.
Conclusion: Canine urinary E. coli in Saskatchewan remain largely susceptible to first line therapies, though resistance, particularly to the aminopenicillins, warrants continued monitoring. Fosfomycin represents a viable alternative option for treating uncomplicated cystitis in canine patients, although continued surveillance is required to identify changes in resistance. This is the first description of E. coli ST131 from a companion animal pathogen in Canada.
Description
Keywords
E. coli, canine, urinary tract infections, antimicrobial resistance, surveillance, Saskatoon, Canada
Citation
Degree
Master of Science (M.Sc.)
Department
Western College of Veterinary Medicine
Program
Veterinary Microbiology