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Updated: Sep 7, 2025
An Allelotyping PCR for Identifying Salmonella enterica serovars Enteritidis, Hadar, Heidelberg, and Typhimurium
Published on: July 22, 2011
Salmonella enterica subsp. II serovar 4,5,12:a:- may cause gastroenteritis infections in humans
Meiying Yan1, Yongming Zhou2, Yang Cao1
1State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Beijing, China.
Abstract:
Some serovars of Salmonella are not or rare found to cause salmonellosis in human. In our clinic-based surveillance, three rare Salmonella 4,5,12:a:- strains were recovered from three patients with diarrhea. To explore their genetic and epidemiological characteristics and pathogenesis, we conducted whole-genome sequencing, in vitro invasion assays in mammalian cells, and in vivo virulence assays in an animal model. The three isolates had indistinguishable molecular patterns and similar genome sequences, and clustered together with an isolate from edible fish traded among countries. The isolates had biochemical reactions identical with those of Salmonella subspecies enterica but belonged to subspecies salamae according to genome phylogeny, revealing a new serovar, S. enterica subsp. II serovar 4,5,12:a:-. The strains contained multiple virulence genes, elicited temporary bacteremia and enteritidis and caused cell damage in the mouse liver and cecum. This study provides evidence that this new Salmonella salamae serovar can infect humans and cause clusters of cases, and whole-genome sequencing detection and surveillance of Salmonella can help to accurately define Salmonella classification and clonality, improve diagnosis, facilitate outbreak detection and aid in the source tracing of salmonellosis epidemics.
Insights
A new Salmonella salamae serovar, identified as S. enterica subsp. II serovar 4,5,12:a:-, was found to cause human diarrhea. Whole-genome sequencing aids in accurate Salmonella classification and outbreak detection.
Area of Science:
- Microbiology
- Genomics
- Infectious Diseases
Background:
- Some Salmonella serovars rarely cause human salmonellosis.
- Three rare Salmonella 4,5,12:a:- strains were identified in patients with diarrhea.
Purpose of the Study:
- To investigate the genetic, epidemiological, and pathogenic characteristics of rare Salmonella 4,5,12:a:- strains.
- To determine if these strains represent a new Salmonella serovar capable of human infection.
Main Methods:
- Whole-genome sequencing
- In vitro invasion assays in mammalian cells
- In vivo virulence assays in a mouse model
Main Results:
- The three isolates were genetically indistinguishable and belonged to Salmonella subspecies salamae, representing a new serovar: S. enterica subsp. II serovar 4,5,12:a:-.
- These strains infected humans, causing diarrhea, temporary bacteremia, and organ damage in mice.
- The isolates clustered with a strain from edible fish, suggesting a potential foodborne source.
Conclusions:
- A novel Salmonella salamae serovar can infect humans and cause disease clusters.
- Whole-genome sequencing is crucial for accurate Salmonella classification, diagnosis, and outbreak surveillance.
