Shiga Toxin–Producing Escherichia coli: Pre- and Postharvest Control Measures To Ensure Safety of Dairy Cattle Products

Abstract

The large number of cases of human illness caused by Shiga toxin-producing Escherichia coli (STEC) worldwide has raised safety concerns for foods of bovine origin. These human illnesses include diarrhea, hemorrhagic colitis, hemolytic uremic syndrome, and thrombotic thrombocytopenic purpura. Severe cases end with chronic renal failure, chronic nervous system deficiencies, and death. Over 100 STEC serotypes, including E. coli O157:H7, are known to cause these illnesses and to be shed in cattle feces. Thus, cattle are considered reservoirs of these foodborne pathogens. Because beef and dairy products were responsible for a large number of STEC outbreaks, efforts have been devoted to developing and implementing control measures that assure safety of foods derived from dairy cattle. These efforts should reduce consumers' safety concerns and support a competitive dairy industry at the production and processing levels. The efficacy of control measures both before harvest (i.e., on-farm management practices) and after harvest (i.e., milk processing and meat packing) for decreasing the risk of STEC contamination of dairy products was evaluated. The preharvest measures included sanitation during milking and management practices designed to decrease STEC prevalence in the dairy herd (i.e., animal factors, manure handling, drinking water, and both feeds and feeding). The postharvest measures included the practices or treatments that could be implemented during processing of milk, beef, or their products to eliminate or minimize STEC contamination.

Foodborne Pathogens in In-Line Milk Filters and Associated On-Farm Risk Factors in Dairy Farms Authorized To Produce and Sell Raw Milk in Northern Italy

“…Wet and dirty bedding and dirty and encrusted water troughs can be reservoirs for VTEC because they create an optimal environment for their growth and survival (21,37,50,54,64). Daily routine interventions such as a frequent cleaning of water troughs, regular cleaning of feed bunks, and the assessment of dryness of bedding offer signifi cant potential to decrease VTEC contamination (28,37) and might also reduce the risk for other pathogens (19). Manure and its handling play a critical role in VTEC prevalence and in the safety of food from dairy cattle (23,28).…”

Prevalence and sources of cheese contamination with pathogens at farm and processing levels

“…has been found to vary substantially, with reported prevalence from 2% to 52% (Husu, Seppänen, Sivelä, & Rauramaa, 1990). The prevalence of Salmonella faecal shedding varied from 1.4% to 27.5% in U.S.A (Kabagambe et al, 2000;Losinger, Wells, Garber, & Hurd, 1995;Wells, Fedorka-Cray, Dargatz, Ferris, & Green, 2001) whereas the prevalence of pathogenic E. coli O157:H7 in faecal samples ranged from 0.2% to 48.8% (Hussein & Sakuma, 2005). Studies have shown that E. coli O157:H7 can persist in manure, water troughs, and other places on farms (Hancock et al, 1998).…”

Regulation of Cell Division, Biofilm Formation, and Virulence by FlhC in Escherichia coli O157:H7 Grown on Meat

“…The severe forms of disease result from the bacterium's capability to produce Shiga toxin (53). Infection in cattle does not produce overt disease (e.g., diarrhea), but cattle can serve as a primary reservoir for humans (24). Transmission occurs via consumption of contaminated meat or meat products, drinking contaminated water, or personal contact (16,35,54).…”