Assessing the cross contamination and transfer rates of Salmonella enterica from chicken to lettuce under different food-handling scenarios

Cross contamination of foodborne pathogens from raw meats to ready-to-eat foods has caused a number of foodborne outbreaks. The cross contamination and transfer rates of Salmonella enterica from chicken to lettuce under various food-handling scenarios were determined. The following scenarios were tested: in scenario 1, cutting board and knife used to cut chicken (10⁶ CFU/g) were also used for cutting lettuce, without washing; in scenario 2, cutting board and knife were washed with water separately after cutting chicken, and subsequently used for cutting lettuce; and in scenario 3, cutting board and knife were thoroughly washed with soap and hot water after cutting chicken, and before cutting lettuce. In each scenario, cutting board, knife, chicken and lettuce were sampled for population of S. enterica. For scenario 1, both before and after cutting lettuce, the cutting board and knife each had about 2 logs CFU/cm² of S. enterica, respectively. The cut lettuce had about 3 logs CFU/g of S. enterica. In scenario 2, fewer organisms (0.5-2.4 logs CFU/g or cm²) were transferred. The transfer rates in both scenarios ranged from 0.02 to 75%. However, in scenario 3, <1 log CFU/g or cm² organisms were detected on lettuce, cutting board or knife, after washing and cutting lettuce. This shows that the FDA recommended practice for cleaning cutting boards is effective in removing S. enterica and preventing cross contamination.