Abstract
BackgroundThe 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).ResultsThe majority of strains harbored Shiga toxin 1 (stx1) and stx1d, stx2 and stx2e, and ehxA genes, while a minority harbored stx2c subtype and eaeA. We identified 10 stx gene combinations; most of strains 31/60 (51.7%) exhibited four copies of stx genes, namely the stx1, stx1d, stx2, and stx2e, 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.ConclusionsThe STEC isolated from animals are virulent, resistant to antimicrobials, and genetically diverse, thus demands greater attention for the potential risk to human.
Highlights
The Shiga toxin-producing Escherichia coli (STEC) represented a great risk to public health
Isolation of STEC and detection of serogroups and serotypes A total of sixty STEC isolates were identified in the 207 collected samples (29%); these were distributed as follows: 7/15 (50%), 14/20 (70%), 5/10 (50%), 6/12 (50%), 19/50 (38%), and 9/100 (9%) from broilers, duck, cattle meat, cow’s milk, human urine, and human ear discharge, respectively
In our analysis of human samples, we found that O15:H2 was the highest and identified in 8/60 (13.3%) of human urine (5 isolates) and ear discharge (3 isolates); O17:H18 was detected in 6/60 (10%) of human urine (3 isolates) and ear discharge (3 isolates); O7:H2 in 3/60 (5%) of human urine, and O8:H21 in 5/60 (8.3%) of human urine (2 isolates) and ear discharge (3 isolates)
Summary
The Shiga toxin-producing Escherichia coli (STEC) represented a great risk to public health. 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 multiplelocus variable-number tandem-repeat analysis (MLVA). Shiga toxin-producing Escherichia coli (STEC) is a pathotype of E. coli that produces Shiga toxins which show molecular similarity to that produced by Shigella dysenteriae type 1 [1]. Many human outbreaks were caused by the top six STEC serogroups, notably O26, O45, O103, O111, O121, and O145 [4]. The incidence of infections caused by one of the top six STEC serogroups in the USA soared from 0.19 per 100.000 in the year 2007 to 0.79 per 100.000 in the year 2014 [1]. The lipopolysaccharide antigen enables E. coli to colonize bladders and increases bacterial resistance against hydrophobic antibiotics [5, 6]
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