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The aim of this research was to identify the presence of integrons among Escherichia coli strains isolated from poultry and swine and to characterize the topological association of these integrons with resistance genes and assess their potential ability to transfer these elements by conjugation. One hundred and seventy-two strains of E. coli were isolated. Their resistance to tetracycline, streptomycin, sulfamethoxazole-trimethoprim, ciprofloxacin, and enrofloxacin was studied by plate dilution. In resistant strains the presence of integrons and resistance genes was assessed by PCR. In the variable region, genes aadA1, dfrA1, and qnr were analyzed. Also, presence of tetA, tetB, and sul1 was assessed. Transference of these genes and integrons in vitro was evaluated by conjugation assays, using E. coli J53 Az^r as recipient strain. Seventy-eight percent and 83% of the poultry and swine strains, respectively, were …