Prevalence and Genetic Characterization of Antimicrobial-resistant Escherichia coli from Wild Boar Meat in Japan.

Antimicrobial-resistant bacteria must be controlled from a "One Health" perspective, including in wild animals and associated products. We examined the prevalence and genetic characteristics of antimicrobial-resistant Escherichia coli in wild boar meat from a local market in Japan. A total of 152 E. coli isolates were recovered from 51 of 62 wild boar meat samples (82.3%). Among these isolates, 11 (7.2%) were resistant to one or more antimicrobial agents, including ampicillin, streptomycin, gentamicin, kanamycin, and tetracycline. Representative genes for antimicrobial resistance, such as the blaTEM, strA, strB, aacC2, aphA1, tetA, and tetB genes, from E. coli isolates exhibiting antimicrobial resistance were detected using PCR. Plasmid sequencing revealed that three representative multidrug-resistant isolates (WB18-2, WB39-2 and WB48-1) carried conjugable plasmids (such as IncF, IncX1, IncY, and IncR) that harbored antimicrobial resistance genes and Tn3 family transposons. The aph(6)-Id, aph(3")-Ib, and tetB genes were found on Tn5393-like transposons; the tetA gene, on Tn1721-like transposons; and the blaTEM gene, on Tn5393-like or Tn3.1 transposons. In contrast, the aacC2, aadA1, aadA2, sul2, sul3, and dfrA12 genes were independent of Tn3 family transposons. These data indicated that the prevalence of antimicrobial-resistant E. coli in wild boar meat was low; however, antimicrobial resistance factors have the potential to be transferred among bacteria via conjugative plasmids.