View Full Version : Organic farming reduces antibiotic resistant bacteria.

09-27-11, 08:52 PM
Sep 26, 2011

Sapkota, AR, RM Hulet, G Zhang, P McDermott, RL Kinney, KJ Schwab and SW Joseph. 2011. Lower prevalence of antibiotic-resistant Enterococci on U.S. conventional poultry farms that transitioned to organic practices. Environmental Health Perspectives http://dx.doi.org/10.1289/ehp.1003350 (http://dx.doi.org/10.1289/ehp.1003350).

Synopsis by Renee Gardner (http://www.environmentalhealthnews.org/ehs/Members/rgardner)

When compared to farms that maintain conventional chicken-raising practices, farmers who switch to organic farming methods reduce antibiotic-resistant bacteria – especially those resistant to more than one antibiotic – that can cause infection in people.

Antibiotic-resistant bacteria were less common on chicken farms that had recently switched to organic farming practices when compared to those that continued to use conventional farming practices, finds a study of organic poultry farms in the Mid-Atlantic region of the United States. The results are published online in the journal Environmental Health Perspectives.
The results show that reducing nontherapeutic use of antibiotics also reduces antibiotic-resistant bacteria in chickens and their waste materials. It is one of the first to examine the changes on farms in the United States. The findings agree with prior studies from Europe and Asia that report similar results: less antibiotic use means fewer resistant bacteria in the animals and food products.
In conventional chicken farming, antibiotic use goes beyond just treating sick chickens. The drugs are often added to feed to promote the growth of chickens living in crowded poultry houses. Antibiotics use increased during the 1990s and a large portion of that increase was due to these so-called nontherapeutic uses.
However, this kind of overuse can increase antibiotic-resistant bacteria in the facilities. The bacteria can then spread to people by either direct contact with the animals, through the handling and eating of meat products and via manure spread on crops and farmland.
This can be a problem because medical complications due to antibiotic-resistant bacteria are becoming more commonplace in hospitals. An infection with antibiotic-resistant bacteria generally means a longer and more serious illness for the patient, as well as more complicated and often more expensive treatments.
Demand for organic chicken is increasing at a time when the prevalence of antibiotic-resistant bacteria is gaining more attention from scientists and the public. Sales of organic chicken quadrupled between 2003 and 2006, making poultry one of the fastest growing organic products. The demand is due in part to consumers' preference and perception that organically-grown poultry is safer than conventionally-raised poultry. This demand has also prompted more farmers to switch from conventional to organic methods.
In this study, a team of researchers from University of Maryland, Pennsylvania State University, the U.S. Department of Agriculture and the Johns Hopkins University took advantage of mid-Atlantic farms that were transitioning to organic practices. The researchers compared five formerly conventional farms that were producing their first flock of certified organic chickens to five farms that continued conventional farming practices, including adding up to six different antibiotics to the feed.
The researchers sampled water, feed and poultry litter – a combination of bedding material such as straw or sawdust, manure, feathers and spilled feed. They cultured bacteria from these samples and tested each for bacteria resistant to a wide variety of antibiotics.
The authors found the same strains of bacteria on both organic and conventional farms. Antibiotic-resistant bacteria were less common in samples from the organic farms. Most of the antibiotic-resistant bacteria were found in the poultry litter samples, though some were also found in food and water samples.
Bacteria that were multi-drug resistant – that is, resistant to three or more kinds of antibiotics – were also less common in samples from organic farms. Forty-two percent of samples isolated from conventional poultry houses were multi-drug resistant, compared to 10 percent of samples isolated from organic farms. Bacteria isolated from conventional farms were more likely to be resistant to antibiotics routinely used for people with infections, such as cyprofloxacin, tetracycline, penicillin and gentamicin.

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