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 Kansas State
University detail their findings
in the August 2009 issue of the journal Applied & Environmental
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
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.
"The prevalences of E.
coli O157:H7 that we observed in organically and naturally raised beef
cattle were similar to the previously reported prevalence in conventionally
raised cattle," the researchers said. "No major differences in
antibiotic susceptibility patterns among the isolates were observed."
The article citation is
S. Reinstein, J.T. Fox, X. Shi, M.J. Alam, D.G. Renter and T.G. Nagaraja.
2009. Prevalence of Escherichia coli O157:H7 in organically and naturally
raised beef cattle. Applied & Environmental Microbiology