A new study suggests that when compared to conventionally raised beef cattle, organic and natural production systems do not impact antibiotic susceptibility of Escherichia coli O157:H7. This discovery emphasizes that although popular for their suggested health benefit, little is actually known about the effects of organic and natural beef production on foodborne pathogens. The researchers from KansasState University detail their findings in the August 2009 issue of the journal Applied & Environmental Microbiology.

Increased outbreaks of foodborne illness, as well as the growing awareness and popularity of organic and natural foods, have forced many cattle farmers to adopt new production methods to meet consumer demand for safe and healthy beef. Organic food sources receive only certified organic feed, are raised without the use of antibiotics, hormones and other veterinary products, and are regulated by the U.S. Department of Agriculture. Natural production guidelines completely restrict the use of antibiotics and hormones but do allow non-organic food sources and are only regulated by the brand name owner.

Cattle are major reservoirs of E. coli O157:H7 and their feces are the main source of food and water contamination that lead to foodborne illness in humans. In the study, fecal samples were collected from organically and naturally raised cattle and tested for the presence of E. coli O157:H7. Results showed prevalence rates of 14.8% in organically raised and 14.2% in naturally raised cattle. These E. coli O157:H7 levels were comparable to those previously identified in conventionally raised cattle, the researchers said. Additionally, the minimum inhibitory concentration of a variety of antibiotics for E. coli O157:H7 isolates were analyzed to determine the effects of all three production systems and no significant difference in antibiotic susceptibility was noted.

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