Abstract
BACKGROUND: The Shiga toxin-producing Escherichia coli (STEC) represented a great risk to public health. In this study, 60 STEC strains recovered from broiler and duck fecal samples, cow's milk, cattle beef, human urine, and ear discharge were screened for 12 virulence genes, phenotypic and genotypic antimicrobial resistance, and multiple-locus variable-number tandem-repeat analysis (MLVA). RESULTS: The majority of strains harbored Shiga toxin 1 (stx(1)) and stx(1d), stx(2) and stx(2e), and ehxA genes, while a minority harbored stx(2c) subtype and eaeA. We identified 10 stx gene combinations; most of strains 31/60 (51.7%) exhibited four copies of stx genes, namely the stx(1), stx(1d), stx(2), and stx(2e), and the strains exhibited a high range of multiple antimicrobial resistance indices. The resistance genes blaCTX-M-1 and blaTEM were detected. For the oxytetracycline resistance genes, most of strains contained tetA, tetB, tetE, and tetG while the tetC was present at low frequency. MLVA genotyping resolved 26 unique genotypes; genotype 21 was highly prevalent. The six highly discriminatory loci DI = 0.9138 are suitable for the preliminary genotyping of STEC from animals and humans. CONCLUSIONS: The STEC isolated from animals are virulent, resistant to antimicrobials, and genetically diverse, thus demands greater attention for the potential risk to human.