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.

Genetic and virulence characteristics of hybrid Shiga toxin-producing and atypical enteropathogenic Escherichia coli strains isolated in South Korea

“…Real-time PCR was performed using a PowerCheckTM 20/15 Pathogen Multiplex Real-time PCR kit (Kogen Biotech Co., Ltd., Seoul, Republic of Korea) to detect virulence genes in different DEC pathogens, including VT1 and VT2 (STEC); bfpA and eaeA (EPEC); LT , STh and STp (ETEC); aggR (EAEC); ipaH (EIEC) ( Lee et al, 2023a , b ).…”

“…We conducted a comparative genomic analysis of 32 hybrid STEC/aEPEC strains isolated in South Korea and 187 other pathogenic E. coli strains ( Lee et al, 2023a , b ). To analyze the pan-genome, we used the bacterial pan-genome analysis (BPGA) tool (v1.3) with default parameters.…”

“…Diarrheal disease outbreaks associated with various DEC pathotypes occurred in Germany in 2011 ( Buchholz et al, 2011 ), Japan in 2016 ( Furukawa et al, 2018 ) and 2020 ( Kashima et al, 2021 ), Nottingham, UK in 2014 ( Newitt et al, 2016 ), South Korea in 2018 ( Lim et al, 2020 ), and the United Kingdom in 2020 ( Mulchandani et al, 2021 ). Hybrid strains are characterized by the presence of virulence genes unique to multiple E. coli pathotypes, typically detected via PCR or comprehensive whole-genome sequencing (WGS) ( Jesser and Levy, 2020 ; Lee et al, 2023a , b ). Cell-based assays have also been used to assess the virulence potential of hybrid strains ( Valiatti et al, 2020 ).…”

Pandemic ST131Escherichia colipresenting the UPEC/EAEC and ExPEC/EAEC hybrid pathotypes recovered from extraintestinal infections in a clinical setting of the Brazilian Amazon region

“…Strains harbouring a blend of virulence markers of different pathotypes have been described worldwide in both high-risk and local lineages, however, most of them correspond to hetero-pathogenic strains (characterized by a combination of virulence markers from DEC pathotypes) [7–9]. A recent study in South Africa demonstrated the high prevalence of several different DEC hybrid pathotypes, including strains sharing three virulence markers of three different DEC pathotypes, which were recovered from inanimate surfaces and presented a higher resistance profile compared to the classic pathotypes identified [8].…”