Antimicrobial Resistance in Escherichia coli Isolated from Wild Animals in Poland

Antimicrobial resistance was tested in Escherichia coli isolated from feces ( n = 660) of red deer, roe deer, fallow deer, European bison, and wild boar shot in regional forests in Poland during two winter hunting seasons. Indicator E. coli ( n = 542) was resistant against 11 of 14 tested compounds, mostly sulfamethoxazole, streptomycin, ampicillin, trimethoprim, and tetracycline (1.3–6.6% range). No significant differences were observed between boar and ruminant isolates. Most of deer and bison isolates showed no resistance. Selective screening of wildlife samples revealed 1.7% prevalence of cephalosporin-resistant E. coli found mostly in wild boars. They produced extended-spectrum beta-lactamases ( bla CTX-M-1 , bla CTX-M-15 ) and plasmid–mediated AmpC-type cephalosporinase ( bla CMY-2 ). The majority of the isolates originated from boars shot in a narrow time frame and space; therefore, common antimicrobial selection pressure in the environment was assumed. Three E. coli isolates carried plasmid–mediated quinolone resistance genes ( qnrS1/S3 ). No transferable colistin resistance mechanisms were found in two resistant E. coli . Transferability of resistance was proved in a single pAmpC-positive isolate carrying IncI1-alpha 95 kb plasmid. No cephalosporin-resistant E. coli harbored pathogenicity markers; therefore, they might be considered a vector of resistance determinants, but not a pathogen themselves.