Dataset Information

Molecular and Genomic Analysis of the Virulence Factors and Potential Transmission of Hybrid Enteropathogenic and Enterotoxigenic Escherichia coli (EPEC/ETEC) Strains Isolated in South Korea.

ABSTRACT: Hybrid strains Escherichia coli acquires genetic characteristics from multiple pathotypes and is speculated to be more virulent; however, understanding their pathogenicity is elusive. Here, we performed genome-based characterization of the hybrid of enteropathogenic (EPEC) and enterotoxigenic E. coli (ETEC), the strains that cause diarrhea and mortality in children. The virulence genes in the strains isolated from different sources in the South Korea were identified, and their phylogenetic positions were analyzed. The EPEC/ETEC hybrid strains harbored eae and est encoding E. coli attaching and effacing lesions and heat-stable enterotoxins of EPEC and ETEC, respectively. Genome-wide phylogeny revealed that all hybrids (n = 6) were closely related to EPEC strains, implying the potential acquisition of ETEC virulence genes during ETEC/EPEC hybrid emergence. The hybrids represented diverse serotypes (O153:H19 (n = 3), O49:H10 (n = 2), and O71:H19 (n = 1)) and sequence types (ST546, n = 4; ST785, n = 2). Furthermore, heat-stable toxin-encoding plasmids possessing estA and various other virulence genes and transporters, including nleH2, hlyA, hlyB, hlyC, hlyD, espC, espP, phage endopeptidase Rz, and phage holin, were identified. These findings provide insights into understanding the pathogenicity of EPEC/ETEC hybrid strains and may aid in comparative studies, virulence characterization, and understanding evolutionary biology.

SUBMITTER: Lee W

PROVIDER: S-EPMC10454139 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature

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Molecular and Genomic Analysis of the Virulence Factors and Potential Transmission of Hybrid Enteropathogenic and Enterotoxigenic Escherichia coli (EPEC/ETEC) Strains Isolated in South Korea.

Lee Woojung W Sung Soohyun S Ha Jina J Kim Eiseul E An Eun Sook ES Kim Seung Hwan SH Kim Soon Han SH Kim Hae-Yeong HY

International journal of molecular sciences 20230812 16

Hybrid strains Escherichia coli acquires genetic characteristics from multiple pathotypes and is speculated to be more virulent; however, understanding their pathogenicity is elusive. Here, we performed genome-based characterization of the hybrid of enteropathogenic (EPEC) and enterotoxigenic E. coli (ETEC), the strains that cause diarrhea and mortality in children. The virulence genes in the strains isolated from different sources in the South Korea were identified, and their phyl ...[more]

PMID: 37628911

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Project description:BackgroundEnterohaemorrhagic E. coli (EHEC) can cause severe disease such as bloody diarrhoea and haemolytic uraemic syndrome in humans. Besides production of Shiga toxins, the presence of LEE (eae-gene) and non-LEE (nle) encoded effector genes harboured on O-islands OI-122, OI-71 and OI-57 is associated with EHEC virulence and their frequency in outbreaks. Genes encoded by the EHEC-plasmid are putative virulence markers of EHEC. EHEC-plasmids, LEE and non-LEE effector genes have also been detected in some strains of enteropathogenic E. coli (EPEC). The objective of this study was to analyze the relationship between EHEC and EPEC for virulence genes encoded by genomic O-islands and by the EHEC-plasmids.ResultsNle genes ent/espL2, nleB and nleE (OI-122), nleA, nleF and nleH1-2 (OI-71), nleG5-2 and nleG6-2 (OI-57), espK (CP-933N) and the EHEC-plasmid encoded genes ehxA, espP, etpD and katP were searched in 73 typical and in 235 atypical enteropathogenic E. coli (EPEC) strains. Typical and atypical EPEC each fall into two clusters. Cluster 1 typical (n = 46) and atypical (n = 129) EPEC strains were characterized by the presence of OI-122 encoded genes and grouped together with 64 investigated EHEC strains. Cluster 2 typical (n = 27) and atypical (n = 106) strains grouped together with 52 LEE-negative, Shiga toxin-producing E. coli (STEC) and with 21 apathogenic E. coli strains. Typical EPEC Cluster 1 strains belonged to serotypes frequently involved in severe illness and outbreaks in children (O111:H2, O114:H2, O55:H6, O127:H6 and O142:H6). Atypical EPEC Cluster 1 strains were characterized by serotypes related to EHEC (O26:H11, O55:H7, O145:H28, O103:H2 and O103:H25).ConclusionThe OI-122 encoded nleB gene was found to be most closely associated with Cluster 1 strains and may serve as a diagnostic tool for the identification of virulent EHEC and EPEC seropathotypes. OI-71 encoded genes nleA, nleF and nleH1-2 are less associated with Cluster 1 strains. EHEC-plasmid, OI-57 and CP-933 associated genes showed only weak similarities with virulent Cluster 1 EHEC and EPEC strains.

Project description:BackgroundShigatoxigenic Escherichia coli (STEC) and enterotoxigenic E. coli (ETEC) cause serious foodborne infections in humans. These two pathogroups are defined based on the pathogroup-associated virulence genes: stx encoding Shiga toxin (Stx) for STEC and elt encoding heat-labile and/or est encoding heat-stable enterotoxin (ST) for ETEC. The study investigated the genomics of STEC/ETEC hybrid strains to determine their phylogenetic position among E. coli and to define the virulence genes they harbor.MethodsThe whole genomes of three STEC/ETEC strains possessing both stx and est genes were sequenced using PacBio RS sequencer. Two of the strains were isolated from the patients, one with hemolytic uremic syndrome, and one with diarrhea. The third strain was of bovine origin. Core genome analysis of the shared chromosomal genes and comparison with E. coli and Shigella spp. reference genomes was performed to determine the phylogenetic position of the STEC/ETEC strains. In addition, a set of virulence genes and ETEC colonization factors were extracted from the genomes. The production of Stx and ST were studied.ResultsThe human STEC/ETEC strains clustered with strains representing ETEC, STEC, enteroaggregative E. coli, and commensal and laboratory-adapted E. coli. However, the bovine STEC/ETEC strain formed a remote cluster with two STECs of bovine origin. All three STEC/ETEC strains harbored several other virulence genes, apart from stx and est, and lacked ETEC colonization factors. Two STEC/ETEC strains produced both toxins and one strain Stx only.ConclusionsThis study shows that pathogroup-associated virulence genes of different E. coli can co-exist in strains originating from different phylogenetic lineages. The possibility of virulence genes to be associated with several E. coli pathogroups should be taken into account in strain typing and in epidemiological surveillance. Development of novel hybrid E. coli strains may cause a new public health risk, which challenges the traditional diagnostics of E. coli infections.

Project description:BackgroundEnteropathogenic Escherichia coli (EPEC) are classified into typical and atypical strains based on the presence of the E. coli adherence factor (EAF) plasmid. The EAF plasmid contains the bfp (bundle-forming pilus) operon and the perABC (plasmid encoded regulator) gene cluster. A 1-kb cryptic region of EAF plasmid has been widely used as a genetic probe for EPEC detection. However, some EPEC strains may harbor an EAF plasmid lacking the EAF probe sequence, which makes the differentiation between typical and atypical a complex task. In this study, we report the genetic analysis of the EAF plasmid-encoded genes in a collection of EPEC clinical isolates.MethodsA total of 222 EPEC clinical isolates, which were previously classified as typical (n=70) or atypical (n=152) by EAF probe reactivity, were screened for the presence of different EAF sequences by PCR and DNA hybridization.ResultsAll typical strains possessed intact bfpA and perA genes, and most of them were positive in the PCR for EAF probe sequence. However, a subset of 30 typical strains, 22 of which belonged to O119 serogroup, presented a 1652 pb deletion in the region between 1093-bp downstream perC and 616-bp of the EAF fragment. The bfpA, bfpG, and per genes were found in all typical strains. In addition, 32 (21%) atypical strains presented the perA gene, and 20 (13.2%) also presented the bfpA gene. Among the 32 strains, 16 belonged to the O119:H2, O119:HND, and ONT:HND serotypes. All 32 atypical strains contained perA mutation frameshifts and possessed an IS1294 element upstream of the per operon as detected by PCR followed by restriction fragment length polymorphism (RFLP) typing and multiplex PCR. Among the 20 bfpA probe-positive strains, eight O119 strains possessed deletion in the bfp operon at the 3'end of bfpA due to an IS66 element.ConclusionOur data show that typical O119 strains may contain a deletion within the EAF probe sequence not previously reported. This new finding suggests that care should be taken when using the previously described EAF PCR assay in epidemiological studies for the detection of typical O119 strains. In addition, we were able to confirm that some atypical strains carry vestiges of the EAF plasmid.

Dataset Information

Molecular and Genomic Analysis of the Virulence Factors and Potential Transmission of Hybrid Enteropathogenic and Enterotoxigenic Escherichia coli (EPEC/ETEC) Strains Isolated in South Korea.

Publications

Molecular and Genomic Analysis of the Virulence Factors and Potential Transmission of Hybrid Enteropathogenic and Enterotoxigenic <i>Escherichia coli</i> (EPEC/ETEC) Strains Isolated in South Korea.

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