title: Colonisation dynamics and virulence of two clonal groups of multidrug-resistant Escherichia coli isolated from dogs.
abstract: The study established the virulence potential of multidrug-resistant Escherichia coli (MDREC) isolates from nosocomial infections in hospitalised dogs. The isolates were resistant to fluoroquinolones, belonged to two distinct clonal groups (CG1 and CG2) and contained a plasmid-mediated AmpC (CMY-7) beta-lactamase. CG1 isolates (n=14) possessed two of 36 assayed extraintestinal virulence genes (iutA and traT) and belonged to phylogenetic group A, whereas CG2 isolates (n=19) contained four such genes (iutA, ibeA, fimH and kpsMT K5) and belonged to group D. In a mouse gastrointestinal tract colonisation model, colonisation by index CG1 strain C1 was transient, in contrast to the index CG2 strain C2b, which persisted up to 40days post-inoculation. In a mouse subcutaneous challenge model, both strains were less virulent than archetypal group B2 extraintestinal pathogenic E. coli (ExPEC) strain CFT073; strain C1 caused no systemic signs and strain C2b was lethal to only one of six mice. In a mouse urinary tract infection model, strain C2b colonised the mouse bladder over 2 logs higher compared to strain C1. Whilst both groups of canine MDREC appear less virulent than a reference human ExPEC strain, CG2 strains have greater capacity for colonisation and virulence.
authors.affiliation: School of Veterinary Science, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Hanna E
authors.initials: HE
authors.lastname: Sidjabat
authors.forename: James J-C
authors.initials: JJ
authors.lastname: Chin
authors.forename: Toni
authors.initials: T
authors.lastname: Chapman
authors.forename: Kent
authors.initials: K
authors.lastname: Wu
authors.forename: Glen C
authors.initials: GC
authors.lastname: Ulett
authors.forename: Cheryl Y
authors.initials: CY
authors.lastname: Ong
authors.forename: Mark A
authors.initials: MA
authors.lastname: Schembri
authors.forename: James R
authors.initials: JR
authors.lastname: Johnson
authors.forename: Darren J
authors.initials: DJ
authors.lastname: Trott
mesh_terms: D000818:Animals; D016470:Bacteremia / Q000382:microbiology; D004195:Disease Models, Animal; D004283:Dog Diseases / Q000382:microbiology*; D004285:Dogs; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D029968:Escherichia coli Proteins / Q000235:genetics*; D005260:Female; D041981:Gastrointestinal Tract / Q000382:microbiology; D006801:Humans; D051379:Mice; D008808:Mice, Inbred CBA; D010802:Phylogeny; D014552:Urinary Tract Infections / Q000382:microbiology; D014774:Virulence / Q000235:genetics
chemical_list: D029968:Escherichia coli Proteins