Enumeration of Escherichia coli Cells on Chicken Carcasses as a Potential Measure of Microbial Process Control in a Random Selection of Slaughter Establishments in the United States

• Published in: Applied and Environmental Microbiology Vol. 75; no. 11; pp. 3522 - 3527
• Main Authors: Altekruse, Sean F, Berrang, Mark E, Marks, Harry, Patel, Bharat, Shaw, William K. Jr, Saini, Parmesh, Bennett, Patricia A, Bailey, J. Stan
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01-06-2009; American Society for Microbiology (ASM)
• Subjects: Abattoirs; Animals; bacterial contamination; bacterial counts; Bacteriology; Biological and medical sciences; Campylobacter; Campylobacter - isolation & purification; carcass evaluation; carcass postchill; carcass rehang; carcass rinses; Carcasses; Cells; chicken carcasses; Chickens - microbiology; Colony Count, Microbial; E coli; Escherichia coli; Escherichia coli - isolation & purification; Food Inspection - methods; Food Microbiology; Food-Processing Industry; Fundamental and applied biological sciences. Psychology; Measurement; Microbiology; monitoring; Poultry; prevalence; process control; quantitative analysis; Random Allocation; Salmonella; Salmonella - isolation & purification; slaughterhouses; statistical models; United States; United States; North America; America; United States > US; Enumeration; Process control; Escherichia coli; Selection; Carcass; Enumeration(counting); Vertebrata; Bacteria; Chicken; Microorganism; Aves; Slaughter; Enterobacteriaceae
• ISSN: 0099-2240; 1098-5336; 1098-6596
• DOI: 10.1128/AEM.02685-08

To evaluate whether the number of Escherichia coli bacteria in carcass rinses from chicken slaughter establishments could be monitored for the purpose of microbial process control, we drew a random sample from 20 of 127 large USDA-inspected operations. In 2005, every 3 months, two sets of 10 carcass rinses, 100 ml each, were collected from establishments, netting 80 sample sets from the rehang and postchill stages. E. coli and Campylobacter numbers and Salmonella prevalence were measured. Mixed-effect models were used to estimate variance of mean log₁₀ E. coli cell numbers of 10-carcass rinse sample sets. Relationships between E. coli and Campylobacter and Salmonella were examined. For 10-carcass rinse sets, at both the rehang and postchill stages the mean log₁₀ E. coli CFU/ml fit the logistic distribution better than the normal distribution. The rehang overall mean log₁₀ E. coli was 3.3 CFU/ml, with a within-sample set standard deviation of 0.6 CFU/ml. The overall postchill mean log₁₀ E. coli was 0.8 CFU/ml, with 13 establishments having mean log₁₀ E. coli CFU/ml values of less than 1.0 and 7 having mean values of 1.2 or more. At the midpoint separating these establishments, a mean log₁₀ E. coli CFU/ml of 1.1, the within-sample set standard deviation was 0.5 CFU/ml, with smaller standard deviations as means increased. Postchill sample sets with mean log₁₀ E. coli counts less than or equal to 1.1 CFU/ml had lower overall prevalence of Salmonella and mean log₁₀ Campylobacter CFU/ml than sample sets with higher means. These findings regarding reductions in E. coli numbers provide insight relevant to microbial process control.