Abstract

JIMENEZ MEJIA, Rafael; GUDINO SOSA, Luis Fernando; AGUILAR LOPEZ, José Antonio  and  LOEZA LARA, Pedro Damián. Molecular characterization of antibiotic resistant Escherichia coli isolated from bovine mastitis in Michoacán, México. Rev. mex. de cienc. pecuarias [online]. 2017, vol.8, n.4, pp.387-396. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v8i4.4251.

In the present study the antibiotic resistance patterns of E. coli isolated from bovine mastitis, as well as the presence of Extended-spectrum β-lactamases (ESBL), tetracycline, streptomycin, and quinolone resistance genes were analyzed. From mastitic cows, milk samples were obtained, of which E. coli were isolated and identified biochemically and confirmed at the molecular level. Genetic analysis revealed that 11.8 % of the E. coli contained a virulence gene encoding intimin (eaeA). All E. coli were resistant to one or more antibiotics, with higher rates of resistance to tetracycline, ampicillin, and cephalothin. In addition, 73.5 % of E. coli were resistant to three or more antibiotics. Of eleven resistance genes analyzed, seven were detected in 79.4 % of the bacterial isolates. Of these, bla CTX-M was found in 16 isolates, tetB in 11, tetA, strA and strB in nine, qnrB in four, and bla TEM in one isolate. About 5.9 % of the E. coli isolates carried class 1 integron integrase gene. In conclusion, a high prevalence of antibiotic resistance in E. coli isolated from bovine mastitis was identified. The bacteria also harbor a virulence gene related to human pathogens and genes conferring resistance to beta-lactam antibiotics, tetracycline, streptomycin, and quinolones.

Keywords : Bovine mastitis; E. coli; Antibiotic resistance; Virulence genes; PCR.

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