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A community outbreak of Salmonella berta associated with a soft cheese product

A Ellis1, M Preston, A Borczyk

  • 1Bureau of Surveillance and Field Epidemiology, Laboratory Centre for Disease Control, Health Canada, Ottawa, Ontario.

Epidemiology and Infection
|April 7, 1998
PubMed

Insights

A 1994 Salmonella berta outbreak in Ontario was linked to unpasteurized cheese. Genomic analysis revealed chicken cross-contamination, highlighting risks from home-based food producers and food safety practices.

Area of Science:

  • Foodborne Pathogen Research
  • Microbial Outbreak Investigation
  • Public Health Surveillance

Background:

  • An increase in Salmonella berta isolates from diarrheal patients in Ontario was reported in 1994.
  • A public health complaint regarding a cheese product coincided with the rise in cases.

Purpose of the Study:

  • To investigate a foodborne illness outbreak linked to a specific cheese product.
  • To identify the causative agent and transmission route of Salmonella berta.

Main Methods:

  • Clinical, environmental, and laboratory investigations were conducted.
  • Pulsed-field gel electrophoresis (PFGE) was used for large fragment genomic fingerprinting of Salmonella berta isolates.
  • Epidemiological data was collected to link illness to specific food consumption.

Main Results:

  • Eighty-two clinical cases of Salmonella berta infection were identified.
  • Illness was strongly linked to the consumption of unpasteurized soft cheese from a farm-based producer.
  • PFGE subtyping indicated indistinguishable isolates from patients, cheese, and chicken, suggesting chicken carcass contamination during cheese production.

Conclusions:

  • Unpasteurized cheese from home-based producers can be a source of foodborne pathogens.
  • Cross-contamination, particularly from poultry, is a significant risk factor in food production.
  • Effective public health surveillance and investigation are crucial for controlling foodborne outbreaks.

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