Experimental cross-contamination of chicken salad with Salmonella enterica serovars Typhimurium and London during food preparation in Cambodian households

PLoS One. 2022 Aug 1;17(8):e0270425. doi: 10.1371/journal.pone.0270425. eCollection 2022.

Abstract

Non-typhoidal Salmonellae are common foodborne pathogens that can cause gastroenteritis and other illnesses in people. This is the first study to assess the transfer of Salmonella enterica from raw chicken carcasses to ready-to-eat chicken salad in Cambodia. Twelve focus group discussions in four Cambodian provinces collected information on typical household ways of preparing salad. The results informed four laboratory experiments that mimicked household practices, using chicken carcasses inoculated with Salmonella. We developed four scenarios encompassing the range of practices, varying by order of washing (chicken or vegetables first) and change of chopping utensils (same utensils or different). Even though raw carcasses were washed twice, Salmonella was isolated from 32 out of 36 chicken samples (88.9%, 95% CI: 73.0-96.4) and two out of 18 vegetable samples (11.1%, 95% CI: 1.9-36.1). Salmonella was detected on cutting boards (66.7%), knives (50.0%) and hands (22.2%) after one wash; cross-contamination was significantly higher on cutting boards than on knives or hands (p-value < 0.05). The ready-to-eat chicken salad was contaminated in scenario 1 (wash vegetables first, use same utensils), 2 (wash vegetables first, use different utensils) and 3 (wash chicken first, use same utensils) but not 4 (wash chicken first, use different utensils) (77.8%, 11.1%, 22.2% and 0%, respectively). There was significantly higher Salmonella cross-contamination in scenario 1 (wash vegetables first, use same utensils) than in the other three scenarios. These results show how different hygiene practices influence the risk of pathogens contaminating chicken salad. This information could decrease the risk of foodborne disease in Cambodia and provides inputs to a quantitative risk assessment model.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Asian People
  • Chickens
  • Colony Count, Microbial
  • Food Contamination / analysis
  • Food Contamination / prevention & control
  • Food Handling / methods
  • Food Microbiology
  • Humans
  • London
  • Salads*
  • Salmonella enterica*
  • Salmonella typhimurium
  • Serogroup
  • Vegetables

Grants and funding

This study was under the Safe Food, Fair Food for Cambodia project granted by the American people through the United States Agency for International Development (USAID) and its’s Feed the Future Innovation Lab for Livestock Systems managed by the University of Florida and the CGIAR Research Program on Agriculture for Nutrition and Health (A4NH).