Detection of Escherichia Coli O157: H7 in Fecal Samples in Meat Goats
Mobley, Ray, Madden, Uford, Brooks-Walter, Alexis, Education
Pathogenic Escherichia coli (E. coli) is recognized as one of the most important food borne human pathogens (Anonymous, 1994; Cray, & Moon, 1995, FDA/CFSAN, 1992). Specifically, E. coli O157: H7 was responsible for 17 of the reported 24 cases of food borne illness in humans in the United States between 1982 and 1993 (Anonymous, 1994; Cray & Moon, 1995). Reed and Kaplan, in 1996, estimated 10,000 to 20,000 cases of E. coli O157:H7 infections occurred annually with 500 deaths (Ohio State University Fact Sheet; Reed & Kaplin, 1996). In 2001, the Centers for Disease Control and Prevention (CDC) estimated that E. coli O157:H7 causes 73,000 cases of diarrheal illnesses each year (ARS, 2001).
Although the organism is primarily detected in cattle and sheep, it has also been found in water, raw milk, unpasteurized apple juice, lettuce, sprouts, and yogurt (Agard, Alexander et al, 2002; Dev, Main, and Gould, 1991; Luedtke & Powell, 2002; Samadpour et al, 2002; Savell, & Smith, 2000; Wang & Doyle, 1998). In the United States over the past decade, the number of cases of human foodborne illnesses related to consumption of beef, and fresh produce has increased (FDA/CFSAN; 1992, Luedtke & Powell, 2002). E. coli O157: H7 is a gram-negative bacterium that has principally been found in the digestive tract of cattle and sheep, but has been isolated from other animals including deer, horses, dogs and birds. Feces from theses animals may be the potential primary source for E. coli O157:H7 contamination of numerous food products (Kudva, Blanch, & Hovde, 1998). E. coli O157: H7 has also been isolated from pork, lamb and poultry products (Cray & Moon, 1995; Doyle & Schoeni, 1987).
The bacterium is transmitted to food products primarily through the fecal-oral route or by cross-contamination. This occurs when the organism is deposited in the food from direct or cross contamination during slaughter, processing and preparation. Kudva et al (1998) conducted a study in which cattle and sheep manure was inoculated with E. coli O157:H7 to determine survivability. The study found that the bacterium survived in sheep manure for 21 months and positive culture was found in bovine manure at 47 days. The bacterium in bovine manure frozen at -20[degrees]C survived for at least 100 days, whereas it survived for 100 days in bovine manure incubated at 4[degrees]C or 10[degrees]C (Keene et al, 1997; Kudva, Blanch, & Hovde, 1998; Rice, Hancock & Besser, 1995; U.S. Department of Agriculture Animal and Plant Inspection Service, 1997; Wallace, Cheasty & Jones, 1997). Feeding studies involving human volunteers indicated that colonization of the small intestine may require a large dose (100 million to 10 billion bacteria) of enterotoxigenic E. coli (FDA/CFSAN). The organism is however known to be very virulent and may require as low an infectious dose of less than 100 cfu. In dairy herds, the prevalence and mechanism of transmission of E. coli O157: H7 are poorly understood (Samadpour, Ongerth & Liston, 1990).
The long-term survival of the bacterium in manure also raises concerns for goat feces to serve as a primary source of contamination of goat meat and goat meat products. There have been limited studies conducted to determine the presence of E. coli O157:H7 in goats and sufficient quantities to cause illness. The consumption of goat meat is increasing and is expected to become a significant alternative food source in the United States. Goat milk and goat milk products are used instead of cow's milk by many lactose intolerant consumers, particularly, black infants who cannot digest regular cow's milk. Therefore, there is a need to determine if this organism will constitute a significant hazard for meat and milk products from this species. The purpose of this study was to determine if E. coli O157:H7 is a naturally occurring bacterium in goats and to determine the prevalence of the organism and the related food safety risks that may be associated with the production and consumption of goat meat, and goat meat products. …