A multi-state outbreak of Salmonella bredeney food poisoning: a case control study

Objective: To investigate a multi-state outbreak of Salmonella bredeney: Design: Case: interviews followed by an age and neighbourhood matched case control study. Participants: People with laboratory-confirmed S. bredeney and controls matched on age and geographical location in New South Wales, the Australian Capital Territory, Queensland and Victoria. Results: We identified 157 persons with S. bredeney spread throughout the eastern states and the ACT. In the matched analysis, cold meat and chicken demonstrated a significant odds ratio of 4.4 (p=0.017) and 4.2 (p=0.02) respectively. Among primary cases, the odds ratio for chicken was 6.0 (p=0.01) and for ground pepper was 3.75 (p=0.04). Conclusions: The most likely source of this outbreak was a product contaminated at the point of manufacture and distributed widely within NSW and the ACT and, to a lesser extent, Queensland (Brisbane) and Melbourne. The most probable food is a meat or chicken product, followed by substantial cross contamination of other meat products at retail outlets, which served to amplify the outbreak.