Project Summary

The prevalence of Escherichia coli O157:H7 and indicator organisms on the surface of intact beef sub-primals prior to further processing

Principle Investigator(s):
James E. Kennedy Jr., Sally K. Williams, Ted Brown, and Phil Minerich
University of Florida
Completion Date:
May 2006



In January 1999, the United States Department of Agriculture Food Safety Inspection Service (USDA FSIS) published a statement clarifying that public health risk posed by E. coli O157:H7 was not limited to raw ground beef products, but included intact raw beef such as trimmings that are to be further processed into non-intact products. FSIS determined that if these types of intact beef products are positive for E. coli O157:H7, then they must be processed into ready-to-eat products or be deemed adulterated (14, 15). This notice was a result of concerns that intact cuts of beef that are further processed into non-intact products may have pathogens introduced below the meat surface, and therefore, require a higher internal cook temperature to render the product safe for consumption. In October 1994, FSIS declared E. coli O157:H7 to be an adulterant in raw ground beef and began a sampling program to test for the pathogen in federally inspected establishments and retail stores (15). E. coli O157:H7 was first recognized as a pathogen in 1982 when it was identified as the causative agent of two outbreaks involving the consumption of undercooked ground beef leading to hemorrhagic colitis (5, 9). The organism also achieved notoriety in 1993 after a multi-state outbreak resulted in four deaths (13). The Center for Disease Control estimated that more than 73,000 cases of infection and 61 deaths occur in the United States each year due to E. coli O157:H7 (4). 

Cattle have been implicated as a primary reservoir for the transmission of verocytotoxigenic E. coli (11, 16). It has been reported that the pathogen can be carried in the rumen (10, 11, 13), on the hide (1) and excreted in feces (6). The prevalence of E. coli O157:H7 on hides may reflect many sources of contamination such as soil, feces from other animals and lairage (2). In a study conducted in three large U.S. Midwestern fed-beef processing plants, E. coli O157:H7 was recovered from 5.9% of fecal samples, 60.6% of hide samples, and 26.7% of carcasses sampled before the pre-evisceration wash (2). The pathogen also was recovered from 1.2% (15 of 1,232) of carcasses sampled at chilling (postintervention) at approximate levels of 3.0 cells per 100 cm2 (2). 

Exposure to E. coli O157:H7 has been linked with life-threatening human illnesses that include hemorrhagic colitis and hemolytic uremic syndrome (3). In general, the organism colonizes the gastrointestinal tract of ruminants, including healthy adult cattle (7). Consequently, the beef carcasses may become contaminated during slaughter and processing (5). Since cattle are considered the main reservoir of E. coli O157:H7 and many outbreaks are associated with the consumption of undercooked beef, it is necessary to determine the extent to which E. coli O157:H7 is present on the surface of intact sub-primal cuts prior to mechanical tenderization/enhancement. The objectives of this study were to determine the prevalence of E. coli O157:H7 and indicator organisms (generic E. coli, total coliforms and aerobic plate count organisms) on the surface of intact beef sub-primals prior to the enhancement process.

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