The efficacy of interventions applied during primary processing on contamination of beef carcasses with Escherichia coli: A systematic review-meta-analysis of the published research

Results from primary processing intervention strategies for Escherichia coli reduction on beef carcasses are often inconsistent or contradictory. Our objective was to identify, critically evaluate and synthesize published intervention research reporting treatment efficacy at the abattoir on E. coli contamination of beef carcasses using systematic review (SR)–meta-analysis (MA) methodology to recommend effective practices and determine knowledge gaps. Four electronic bibliographic databases were searched for intervention studies in English. Two independent reviewers performed all SR steps. Risk of bias was assessed and separate random-effects MAs conducted on datasets. A stochastic simulation model using MA effect estimates evaluated combined effects of potable water carcass wash, steam or hot water pasteurization and a 24h dry chill. The SR-MA included 36 citations (202 trials). Although 44 interventions were identified at nine stages of processing, MA was precluded for most due to small study numbers, high risk of bias and heterogeneity. Reduced odds of generic E. coli carcass contamination demonstrated by MA: final carcass washing (OR 0.56, CI: 0.41–0.77), pasteurization (OR 0.09, CI: 0.06–0.14) and 24h dry chilling (OR 0.17, CI: 0.11–0.24). Combining effects of potable water carcass wash, steam or hot water pasteurization and a 24h dry chill, assuming no additional contamination and all variables constant, resulted in a reduced prevalence of 1.22% (CI 0.17, 3.57). The predicted risk difference in carcass contamination was 14, 42 and 35 per 100 carcasses upon application of final wash, carcass pasteurization and 24h dry chill, respectively. Existing research indicates that final wash, hot water or steam pasteurization, and dry chilling are beneficial for reducing the contamination of beef carcasses with generic E. coli and potentially pathogenic strains.