Pathogenic characteristics of an aggregated diarrhea event caused by Plesiomonas shigelloides from stream

TL;DR

This study identified Plesiomonas shigelloides as the cause of a foodborne disease outbreak in Huzhou, using genomic and molecular methods to trace its origin and resistance patterns.

Contribution

The first reported outbreak of Plesiomonas shigelloides in Huzhou, demonstrating the utility of whole genome sequencing in outbreak investigations.

Findings

Seven Plesiomonas shigelloides strains were isolated, showing identical PFGE patterns and resistance to multiple antibiotics.

Genomic analysis revealed 11 mutation sites and homology among outbreak strains.

Whole genome sequencing proved effective as a complementary tool to PFGE for outbreak tracing.

Abstract

This study aimed to investigate the cause of a foodborne disease outbreak in Huzhou on August 14, 2023. Multiple enteropathogens were detected using FilmArray, and the pathogen was subsequently isolated and cultured from anal swabs of the cases and stream water. The isolated strains were identified using VITEK MS, and antimicrobial susceptibility test, pulsed field gel electrophoresis (PFGE) molecular typing, and whole genome sequencing (WGS) were performed on the isolates of Plesiomonas shigelloides. Gene annotation and sequence alignment were used to analyze the virulence genes and drug resistance genes of the strains. A phylogenetic tree was constructed based on single nucleotide polymorphism (SNP), and homology analysis was conducted to trace the origin of P. shigelloides. A total of 7 strains of P.shigelloides were isolated, with 3 from stream water and 4 from anal swabs. All 7 strains exhibited the same PFGE pattern and showed resistance to amikacin, trimethoprim-sulfamethoxazole, chloramphenicol, tetracycline, cefazolin, streptomycin, and florfenicol. The isolated strains carried the same resistance genes and virulence factors. In the sequences of the isolated strains from this outbreak, 11 mutation sites were detected. The phylogenetic tree based on SNP sites showed that these strains were homologous. This foodborne disease outbreak caused by P.shigelloides was the first reported in Huzhou. WGS can be used as a complementary method to PFGE for epidemiological investigations of disease outbreaks.

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