Abstract
Diarrheagenic Escherichia coli is the causative agent of diarrhea in infants and animals worldwide. Many isolated strains recovered from pigs with postweaning diarrhea are multidrug resistance (MDR), and hybrids of E. coli are potentially more virulent, as enterotoxigenic E. coli (ETEC)/Shiga-toxigenic E. coli (STEC) hybrids. Here, we used whole-genome sequencing to analyze clinical isolates of the five colistin-resistant E. coli. The E. coli CAU15104, CAU15134, and CAU16060 belonged to ETEC/STEC hybrids, displaying the same serotype O3:H45 and sequence type ST4214. The E. coli CAU16175 and CAU16177 belonged to atypical enteropathogenic E. coli (aEPEC), display O4:H11 and O103:H2, ST29, and ST20, respectively. The E. coli CAU16175 carries six plasmids. An IncHI2-type plasmid, pCAU16175_1, harbors an IS26-enriched MDR region, which includes 16 antimicrobial-resistant genes. An IncFII-type plasmid, pCAU16175_3, harbors mcr-1.1, tet(M), and blaTEM−1B, whereas mcr-1.1 is located within a Tn2 derivative. Our findings indicate that the ETEC/STEC strains of the O3:H45 serotype as well as the aEPEC strains of the O4:H11 and O103:H2 serotypes are associated with postweaning diarrhea in swine and that some of diarrheagenic E. coli contains IS26-enriched MDR region and the mcr-1 gene located within a Tn2 derivative on IncFII plasmid.
Highlights
Diarrheagenic Escherichia coli (DEC) is a leading cause of infectious diarrhea in humans and animals around the world [1, 2]
The clinical isolates of the E. coli CAU15104, CAU15134, and CAU16060 belonged to enterotoxigenic E. coli (ETEC)/Shiga-toxigenic E. coli (STEC) hybrid strains, display the same serotype O3:H45 and sequence type ST4214, which are identical sequence type with the strains swine19 (LVMV00000000), swine22 (LVMY00000000), swine54 (LVMV00000000), and swine67 (LVOR00000000) from the NCBI database, all carrying fedA, fedF, iha, stb, ltcA, sepA, stx2A, and stx2B virulence genes and antimicrobial-resistant
Most of the isolates belonged to ETEC, followed by atypical enteropathogenic E. coli (EPEC) (aEPEC), which is similar to the report in Spain; that is, most cases of postweaning diarrhea (PWD) are significantly associated with ETEC (67%) and aEPEC
Summary
Diarrheagenic Escherichia coli (DEC) is a leading cause of infectious diarrhea in humans and animals around the world [1, 2]. Diarrheagenic E. coli has six well-described pathotypes: enteropathogenic E. coli (EPEC), which is subdivided into typical EPEC (tEPEC) and atypical EPEC (aEPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli, enteroaggregative E. coli, diffusely adherent E. coli, and enterohemorrhagic E. coli, which is subgroup of Shiga-toxigenic E. coli (STEC) [3, 4]. All of these DECs possess diverse virulence factors, which are encoded by virulence genes and are responsible for their pathogenicity [5]. Enteropathogenic E. coli strains are defined as forming the attaching and effacing (A/E) lesions mediated by genes located on the locus of enterocyte effacement (LEE) pathogenicity island (including eae) in the intestinal epithelium but not produce Shiga-like toxin
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