A COMMUNITY OUTBREAK OF SALMONELLA-BERTA ASSOCIATED WITH A SOFT CHEESE PRODUCT

In September 1994, a complaint was registered at a public health unit concerning a cheese product. In addition, public health laboratories i n Ontario reported an increase in the number of isolates of Salmonella berta from patients with diarrhoeal illness. A clinical, environmenta l and laboratory investigation was initiated to determine the nature o f this outbreak. Isolates of Salmonella berta were compared using larg e fragment genomic fingerprinting by pulsed-held gel electrophoresis ( PFGE), By late October, 82 clinical cases had been identified includin g 35 confirmed, 44 suspected and 3 secondary. The investigation linked illness to consumption of an unpasteurized soft cheese product produc ed on a farm and sold at farmers' markets. Subtyping results of patien t, cheese and chicken isolates were indistinguishable, suggesting that the cheese was contaminated by chicken carcasses during production. T he outbreak illustrates the potential role of uninspected home-based f ood producers and of cross-contamination in the transmission of foodbo rne bacterial pathogens.