Genetic Characterization of AmpC and Extended-Spectrum Beta-Lactamase Phenotypes in and From Alberta Broiler Chickens.

Horizontal gene transfer is an important mechanism which facilitates bacterial populations in overcoming antimicrobial treatment. In this study, a total of 120 and 62 subsp. isolates were isolated from broiler chicken farms in Alberta. Fourteen serovars were identified among isolates. Thirty one percent of isolates (37/120) were multiclass drug resistant (resistant to ≥ 3 drug classes), while only about 16% of isolates (10/62) were multiclass drug resistant. Among those, eight isolates had an AmpC-type phenotype, and one isolate had an extended-spectrum beta-lactamase (ESBL)-type beta-lactamase phenotype. We identified both AmpC-type () and ESBL-type () genes in both and isolates. Plasmids from eight of nine and isolates were transferred to recipient strain J53 through conjugation. Transferable plasmids in the eight and isolates were also transferred into a lab-made sodium azide-resistant recipient through conjugation. The class 1 integrase gene, , was detected on plasmids from two isolates. Further investigation of class 1 integron cassette regions revealed the presence of an gene encoding streptomycin 3''-adenylyltransferase, an / gene encoding aminoglycoside 3''-O-adenyltransferase, and a putative adenylyltransferase gene. This study provides some insight into potential horizontal gene transfer events of antimicrobial resistance genes between and in broiler chicken production.