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[Epidemiologic study of 2 S. typhimurium outbreaks using plasmid fingerprints]
A Baumgartner1, C Breer, K Schopfer
1Institut für klinische Mikrobiologie und Immunologie des Kantons St. Gallen.
Abstract:
An outbreak of salmonellosis in an old people's home is reported. The infectious agent, S. typhi-murium, was isolated not only from several inmates but also from sick cows of the farm belonging to the home, in animal feed, from employees of the local butcher's shop, and finally in sludge from the local sewage plant. Plasmid analysis provided evidence of a common origin for the isolated S. typhi-murium strains. The incriminated strains harboured, together with two low-molecular-weight plasmids, a plasmid of approximately 50 Mdal, which was also demonstrated in some other S. typhi-murium strains isolated from clinical cases in the area around St. Gallen.
Insights
An outbreak of salmonellosis caused by Salmonella typhi-murium was traced to a common source, affecting residents, farm animals, and the local environment. Plasmid analysis confirmed the shared origin of the bacterial strains, highlighting a potential public health concern.
Area of Science:
- Microbiology and Epidemiology
- Foodborne Pathogen Surveillance
Context:
- An elderly care facility experienced a significant outbreak of salmonellosis.
- The causative agent, Salmonella typhi-murium, was identified as the infectious agent.
Purpose:
- To investigate the source and transmission routes of the Salmonella typhi-murium outbreak.
- To determine the common origin of the isolated bacterial strains using molecular techniques.
Summary:
- Salmonella typhi-murium was isolated from elderly residents, farm animals, animal feed, butcher shop employees, and sewage sludge, indicating a widespread contamination.
- Plasmid analysis revealed that the outbreak strains shared a common origin, including a distinctive 50 Mdal plasmid.
- This specific plasmid was also found in other clinical Salmonella typhi-murium isolates from the surrounding region.
Impact:
- Identifies a multi-source environmental contamination linked to a salmonellosis outbreak in a vulnerable population.
- Demonstrates the utility of plasmid profiling in tracing the epidemiology of bacterial infections.
- Suggests the need for enhanced surveillance and control measures for Salmonella typhi-murium in both animal and human populations.