The Effects of Cleaning and Disinfection in Reducing Salmonella Contamination in a Laboratory Model Kitchen

Aims: To establish a laboratory model to compare the effectiveness of detergent-based disinfection procedures for reducing cross-contamination risks during handling of contaminated chicken.

Methods And Results: During handling of chickens, artificially contaminated with Salmonella enteritidis PT4, the organism was widely spread to hands, cloths, and hand- and food-contact surfaces. Hygiene procedures were assessed on the basis of their ability to reduce the number of recoverable salmonellas to <1 CFU. Although detergent-based cleaning using a typical bowl-wash routine without rinsing produced some risk reduction (from 100 to 61.4% of contaminated surfaces), it was insufficient to consistently restore surfaces to a hygienic state. By combining detergent-based cleaning with a rinsing step or with hypochlorite at 500 ppm (of available chlorine) some further reduction in microbial risk was achieved, but was not considered satisfactory for food hygiene purposes. By contrast the risk reduction produced by hypochlorite at 5000 ppm was highly significant and was sufficient to reduce the number of contaminated surfaces to 2.9%.

Conclusions: A key step in achieving a hygienic state through detergent-based cleaning is rinsing but even this will not produce a 'hygienic' result for difficult surfaces such as the chopping board or the dishcloth. Disinfectant compounds should be considered in order to reduce the potential for foodborne cross infection within the home environment.

Significance And Impact Of The Study: Although tests are available to determine the performance of disinfectants, there are no quantitative procedures available to compare the risk reduction achieved by disinfection with that produced by detergent-based procedures. This study describes a reproducible laboratory method which can be used to differentiate the effectiveness of different hygiene procedures for reducing cross-contamination risks during food handling.