Dynamics of extended-spectrum cephalosporin resistance in pathogenic Escherichia coli isolated from diseased pigs in Quebec, Canada.
The aim of this study was to investigate the evolution with time of ceftiofur-resistant Escherichia coli clinical isolates from pigs in Québec, Canada, between 1997 and 2012 with respect to pathotypes, clones and antimicrobial resistance. Eighty-five ceftiofur-resistant E. coli isolates were obtained from the OIE (World Organisation for Animal Health) Reference Laboratory for Escherichia coli. The most prevalent pathovirotypes were enterotoxigenic E. coli (ETEC):F4 (40%), extraintestinal pathogenic E. coli (ExPEC) (16.5%) and Shiga toxin-producing E. coli (STEC):F18 (8.2%). Susceptibility testing to 15 antimicrobial agents revealed a high prevalence of resistance to 13 antimicrobials, with all isolates being multidrug-resistant. blaCMY-2 (96.5%) was the most frequently detected β-lactamase gene, followed by blaTEM (49.4%) and blaCTX-M (3.5%). Pulsed-field gel electrophoresis (PFGE) applied to 45 representative E. coli isolates revealed that resistance to ceftiofur is spread both horizontally and clonally. In addition, the emergence of extended-spectrum β-lactamase-producing E. coli isolates carrying blaCTX-M was observed in 2011 and 2012 in distinct clones. The most predominant plasmid incompatibility (Inc) groups were IncFIB, IncI1, IncA/C and IncFIC. Resistance to gentamicin, kanamycin and chloramphenicol as well as the frequency of blaTEM and IncA/C significantly decreased over the study period, whereas the frequency of IncI1 and multidrug resistance to seven antimicrobial categories significantly increased. These findings reveal that extended-spectrum cephalosporin-resistant porcine E. coli isolates in Québec belong to several different clones with diverse antimicrobial resistance patterns and plasmids. Furthermore, blaCMY-2 was the major β-lactamase gene in these isolates. From 2011, we report the emergence of blaCTX-M in distinct clones.
OIE Reference Laboratory for Escherichia coli (EcL), Centre de recherche en infectiologie porcine et aviaire (CRIPA), Faculté de médecine vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada.
Seyedehameneh
S
Jahanbakhsh
School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy Campus, Mudla Wirra Road, Roseworthy, SA 5371, Australia.
Matthew G
MG
Smith
OIE Reference Laboratory for Escherichia coli (EcL), Centre de recherche en infectiologie porcine et aviaire (CRIPA), Faculté de médecine vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada.
Hamid-Reza
HR
Kohan-Ghadr
NSERC Industrial Research Chair in Meat Safety, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, QC, Canada.
Ann
A
Letellier
School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150, Australia.
Sam
S
Abraham
School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy Campus, Mudla Wirra Road, Roseworthy, SA 5371, Australia.
Darren J
DJ
Trott
OIE Reference Laboratory for Escherichia coli (EcL), Centre de recherche en infectiologie porcine et aviaire (CRIPA), Faculté de médecine vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada. Electronic address: john.morris.fairbrother@umontreal.ca.
John Morris
JM
Fairbrother
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018550:Cephalosporin Resistance; D002511:Cephalosporins / Q000494:pharmacology*; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D014644:Genetic Variation; D005838:Genotype; D058889:Molecular Typing; D015995:Prevalence; D011792:Quebec / Q000453:epidemiology; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000382:microbiology*
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; C053503:ceftiofur
Escherichia coli; Extended-spectrum cephalosporin resistance; Pig; Plasmid; blaCMY-2; blaCTX-M