Clonal group distribution of fluoroquinolone-resistant Escherichia coli among humans and companion animals in Australia.
OBJECTIVE
To determine the phylogenetic group distribution and prevalence of three major globally disseminated clonal groups [clonal group A (CGA) and O15:K52:H1, associated with phylogenetic group D, and sequence type ST131, associated with phylogenetic group B2] among fluoroquinolone-resistant extra-intestinal Escherichia coli isolates from humans and companion animals in Australia.


METHODS
Clinical extra-intestinal fluoroquinolone-resistant E. coli isolates were obtained from humans (n = 582) and companion animals (n = 125), on Australia's east coast (October 2007-October 2009). Isolates were tested for susceptibility to seven antimicrobial agents, and for phylogenetic group, O type and clonal-group-specific single nucleotide polymorphisms by PCR.


RESULTS
The fluoroquinolone-resistant isolates were typically resistant to multiple agents (median of four). Analysis revealed that clonal group ST131 accounted for a large subset of the human isolates (202/585, 35%), but for a much smaller proportion of the companion animal isolates (9/125, 7.2%; P <or= 0.001). In contrast, CGA and O15:K52:H1 were uncommon among both human (7.2%) and companion animal (0.8%) isolates.


CONCLUSIONS
In Australia, a large proportion (42%) of recent fluoroquinolone-resistant extra-intestinal E. coli isolates from humans are represented by three major globally disseminated clonal groups, predominantly ST131, which by contrast is comparatively rare among fluoroquinolone-resistant E. coli from companion animals. In conjunction with Australia's ban on fluoroquinolone use in livestock, these results argue against a major domestic food animal or companion animal source for fluoroquinolone-resistant extra-intestinal E. coli among humans in Australia. However, both humans and companion animals are involved in the intercontinental emergence and dissemination of ST131.
Platell
Joanne L
JL
School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia. j.platell@uq.edu.au
Cobbold
Rowland N
RN
Johnson
James R
JR
Trott
Darren J
DJ
D000818:Animals; D000829:Animals, Domestic / Q000382:microbiology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001315:Australia / Q000453:epidemiology; D015373:Bacterial Typing Techniques; D002415:Cats; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D004285:Dogs; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000145:classification* / Q000187:drug effects / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology* / Q000662:veterinary*; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D010802:Phylogeny
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D024841:Fluoroquinolones