Applied and Environmental Microbiology, November 2009, p. 6955-6962, Vol. 75, No. 22
0099-2240/09/$08.00+0 doi:10.1128/AEM.00375-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Pathotype and Antibiotic Resistance Gene Distributions of Escherichia coli Isolates from Broiler Chickens Raised on Antimicrobial-Supplemented Diets
,
Claudie Bonnet,1
Fatoumata Diarrassouba,2
Roland Brousseau,1,3
Luke Masson,1,3
Edward Topp,4 and
Moussa S. Diarra2*
National Research Council of Canada, Biotechnology Research Institute, Montreal, Quebec, Canada H4P 2R2,1 Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, Agassiz, British Columbia, Canada V0M 1A0,2 Département de Microbiologie et Immunologie, Université de Montréal, Montréal, Québec, Canada H3T 1J42,3 Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada N5V 4T34
Received 16 February 2009/ Accepted 29 August 2009
The impact of feed supplementation with bambermycin, monensin, narasin, virginiamycin, chlortetracycline, penicillin, salinomycin, and bacitracin on the distribution of Escherichia coli pathotypes in broiler chickens was investigated using an E. coli virulence DNA microarray. Among 256 E. coli isolates examined, 59 (23%) were classified as potentially extraintestinal pathogenic E. coli (ExPEC), while 197 (77%) were considered commensal. Except for chlortetracycline treatment, the pathotype distribution was not significantly different among treatments (P > 0.05). Within the 59 ExPEC isolates, 44 (75%) were determined to be potentially avian pathogenic E. coli (APEC), with the remaining 15 (25%) considered potentially "other" ExPEC isolates. The distribution within phylogenetic groups showed that 52 (88%) of the ExPEC isolates belonged to groups B2 and D, with the majority of APEC isolates classified as group D and most commensal isolates (170, 86%) as group A or B1. Indirect assessment of the presence of the virulence plasmid pAPEC-O2-ColV showed a strong association of the plasmid with APEC isolates. Among the 256 isolates, 224 (88%) possessed at least one antimicrobial resistance gene, with nearly half (107, 42%) showing multiple resistance genes. The majority of resistance genes were distributed among commensal isolates. Considering that the simultaneous detection of antimicrobial resistance tet(A), sulI, and blaTEM genes and the integron class I indicated a potential presence of the resistance pAPEC-O2-R plasmid, the results revealed that 35 (14%) of the isolates, all commensals, possessed this multigene resistance plasmid. The virulence plasmid was never found in combination with the antimicrobial resistance plasmid. The presence of the ColV plasmid or the combination of iss and tsh genes in the majority of APEC isolates supports the notion that when found together, the plasmid, iss, and tsh serve as good markers for APEC. These data indicate that different resistant E. coli pathotypes can be found in broiler chickens and that the distribution of such pathotypes and certain virulence determinants could be modulated by antimicrobial agent feed supplementation.
* Corresponding author. Mailing address: P.O. Box 1000, 6947 Highway 7, Agassiz, BC, Canada V0M 1A0. Phone: (604) 796-2221. Fax: (604) 796-0359. E-mail: Moussa.Diarra{at}agr.gc.ca
Published ahead of print on 11 September 2009.
In memory of Roland Brousseau.
Applied and Environmental Microbiology, November 2009, p. 6955-6962, Vol. 75, No. 22
0099-2240/09/$08.00+0 doi:10.1128/AEM.00375-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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