Identification of bla(CMY-7) and associated plasmid-mediated resistance genes in multidrug-resistant Escherichia coli isolated from dogs at a veterinary teaching hospital in Australia.
OBJECTIVE
To determine clonality and identify plasmid-mediated resistance genes in 11 multidrug-resistant Escherichia coli (MDREC) isolates associated with opportunistic infections in hospitalized dogs in Australia.


METHODS
Phenotypic (MIC determinations, modified double-disc diffusion and isoelectric focusing) and genotypic methods (PFGE, plasmid analysis, PCR, sequencing, Southern hybridization, bacterial conjugation and transformation) were used to characterize, investigate the genetic relatedness of, and identify selected plasmid-mediated antimicrobial resistance genes, in the canine MDREC.


RESULTS
Canine MDRECs were divided into two clonal groups (CG 1 and 2) with distinct restriction endonuclease digestion and plasmid profiles. All isolates possessed bla(CMY-7) on an approximately 93 kb plasmid. In CG 1 isolates, bla(TEM), catA1 and class 1 integron-associated dfrA17-aadA5 genes were located on an approximately 170 kb plasmid. In CG 2 isolates, a second approximately 93 kb plasmid contained bla(TEM) and unidentified class 1 integron genes, although a single CG 2 strain carried dfrA5. Antimicrobial susceptibility profiling of E. coli K12 transformed with CG 2 large plasmids confirmed that the bla(CMY-7)-carrying plasmid did not carry any other antimicrobial resistance genes, whereas the bla(TEM)/class 1 integron-carrying plasmid carried genes conferring resistance to tetracycline and streptomycin also.


CONCLUSIONS
This is the first report on the detection of plasmid-mediated bla(CMY-7) in animal isolates in Australia. MDREC isolated from extraintestinal infections in dogs may be an important reservoir of plasmid-mediated resistance genes.
Sidjabat
Hanna E
HE
School of Veterinary Science, The University of Queensland, Brisbane, QLD 4072, Australia.
Townsend
Kirsty M
KM
Hanson
Nancy D
ND
Bell
Jan M
JM
Stokes
H W
HW
Gobius
Kari S
KS
Moss
Susan M
SM
Trott
Darren J
DJ
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001315:Australia; D001483:Base Sequence; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000235:genetics; D004283:Dog Diseases / Q000382:microbiology*; D004285:Dogs; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D005798:Genes, Bacterial; D006762:Hospitals, Animal; D006784:Hospitals, Teaching; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D016133:Polymerase Chain Reaction
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial