title: Quantification and variability analysis of bacterial cross-contamination rates in common food service tasks.
abstract: This study investigated bacterial transfer rates between hands and other common surfaces involved in food preparation in the kitchen. Nalidixic acid-resistant Enterobacter aerogenes B199A was used as a surrogate microorganism to follow the cross-contamination events. Samples from at least 30 different participants were collected to determine the statistical distribution of each cross-contamination rate and to quantify the natural variability associated with that rate. The transfer rates among hands, foods, and kitchen surfaces were highly variable, being as low as 0.0005% and as high as 100%. A normal distribution was used to describe the variability in the logarithm of the transfer rates. The mean +/- SD of the normal distributions were, in log percent transfer rate, chicken to hand (0.94 +/- 0.68), cutting board to lettuce (0.90 +/- 0.59), spigot to hand (0.36 +/- 0.90), hand to lettuce (-0.12 +/- 1.07), prewashed hand to postwashed hand (i.e., hand washing efficiency) (-0.20 +/- 1.42), and hand to spigot (-0.80 +/- 1.09). Quantifying the cross-contamination risk associated with various steps in the food preparation process can provide a scientific basis for risk management efforts in both home and food service kitchens.
authors.affiliation: Food Risk Analysis Initiative, Rutgers-the State University of New Jersey, New Brunswick 08901-8520, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
authors.forename: K M
authors.initials: KM
authors.lastname: Jackson
authors.forename: F P
authors.initials: FP
authors.lastname: Chea
authors.forename: D W
authors.initials: DW
authors.lastname: Schaffner
mesh_terms: D000818:Animals; D002645:Chickens; D015169:Colony Count, Microbial; D021902:Enterobacter aerogenes; D005069:Evaluation Studies as Topic; D005260:Female; D005506:Food Contamination / Q000517:prevention & control; D005511:Food Handling; D005516:Food Microbiology; D006225:Hand / Q000382:microbiology; D006801:Humans; D007700:Kinetics; D018545:Lactuca / Q000382:microbiology; D008297:Male; D008460:Meat / Q000382:microbiology; D012308:Risk Management; D016008:Statistical Distributions