Survival of Campylobacter jejuni in frozen chicken meat and risks associated with handling contaminated chicken in the kitchen

Abstract

Most Campylobacter infections in humans are sporadic cases, often connected to private households. Chicken meat is believed to be the main source of human exposure to Campylobacter and there are significant risks of cross-contamination when handling Campylobacter -contaminated chicken in the kitchen. One post-harvest preventive measure to reduce Campylobacter concentrations on chicken meat is freezing. This study examined survival of different sequence types of C. jejuni during freezing and risk factors during handling of C. jejuni –contaminated chicken meat in the kitchen. Chicken fillets were artificially contaminated before freezing with two different sequence types of C. jejuni (ST-257 and ST-918), at concentrations in the meat of 4.1 log 10 CFU/g (low) and 5.3 log 10 CFU/g (high). Risk factors in the kitchen were assessed by swabbing gloves before and after washing, to simulate hands before and after washing. Utensils such as scissors and forceps used for cutting were also sampled, while a cutting board was sampled twice to simulate before and after wiping. The greatest decrease in Campylobacter concentrations in the freezer occurred in the first four days and the decrease then flattened off. After 49 days in the freezer, concentrations on meat contaminated with high and low levels of ST-257 decreased by 2.0 log 10 CFU/g and 1.5 log 10 CFU/g, respectively, while concentrations on chicken meat contaminated with a high and low level of ST-918 decreased by 1.0 log 10 CFU/g and 0.7 log 10 CFU/g, respectively. Campylobacter was isolated from all simulated environmental samples. The highest load in the environment of both sequence types was unwashed gloves and the first sampling of the unwiped cutting board. Transfer from gloves and the cutting board was lower after washing/wiping, but high concentrations (≥2 log 10 CFU/mL rinse fluid) of Campylobacter persisted for all samples contaminated with ST-918 and for 18 of 20 samples contaminated with ST-257. In conclusion, there are differences between Campylobacter sequence types in their ability to withstand freezing stress and Campylobacter remaining on hands after washing and on cutting boards after wiping is a likely source of cross-contamination in the kitchen. Highlights • High levels of C. jejuni remain on hands and cutting board after cleaning. • Ability to withstand stress such as freezing differ between C. jejuni sequence types. • Hands and cutting boards have the highest load of C. jejuni in kitchen. • The greatest decrease in C. jejuni occurs in the first four days of freezing. • The C. jejuni reduction during freezing is lower for low-contaminated meat.