Widespread distribution of CTX-M and plasmid-mediated AmpC β-lactamases in Escherichia coli   from Brazilian chicken meat

The dissemination of plasmid-mediated antimicrobial resistance genes may pose a substantial public health risk. In the present work, the occurrences of bla_CTX-M and plasmid-mediated ampC and qnr genes were investigated in Escherichia coli from 16 chicken carcasses produced by four commercial brands in Brazil. Of the brands tested, three were exporters, including one of organic chicken. Our study assessed 136 E. coli isolates that were grouped into 77 distinct biotypes defined by their origin, resistance profiling, the presence of β-lactamase and plasmid-mediated quinolone resistance genes and enterobacterial repetitive intergenic consensus-polimerase chain reaction typing. The bla_CTX-M-15, bla_CTX-M-2 and bla_CTX-M-8 genes were detected in one, 17 and eight different biotypes, respectively (45 isolates). Twenty-one biotypes (46 isolates) harboured bla_CMY-2. Additionally, bla_CMY-2 was identified in isolates that also carried either bla_CTX-M-2 or bla_CTX-M-8. The qnrB and/or qnrS genes occurred in isolates carrying each of the four types of β-lactamase determinants detected and also in oxyimino-cephalosporin-susceptible strains. Plasmid-mediated extended-spectrum β-lactamase (ESBL) and AmpC determinants were identified in carcasses from the four brands tested. Notably, this is the first description of bla_CTX-M-15 genes in meat or food-producing animals from South America. The bla_CTX-M-8, bla_CTX-M-15 and bla_CMY-2 genes were transferable in conjugation experiments. The findings of the present study indicate that plasmid-mediated ESBL and AmpC-encoding genes are widely distributed in Brazilian chicken meat.