Monday, March 16, 2009

Husbandry: Houseflies at Poultry Farms Carrying Drug-Resistant Bacteria

Houseflies congregating around broiler poultry farms have once again been linked to drug-resistant bacteria, creating increased risk for human exposure.

The findings of researchers at the Johns Hopkins Bloomberg School of Public Health demonstrate another potential link between industrial food animal production and exposures to antibiotic resistant pathogens. Previous studies have linked antibiotic use in poultry production to antibiotic resistant bacteria in farm workers, consumer poultry products and the environment surrounding confined poultry operations, as well as releases from poultry transport.

"Flies are well-known vectors of disease and have been implicated in the spread of various viral and bacterial infections affecting humans, including enteric fever, cholera, salmonellosis, campylobacteriosis and shigellosis," said Dr. Jay Graham. "Our study found similarities in the antibiotic-resistant bacteria in both the flies and poultry litter we sampled. The evidence is another example of the risks associated with the inadequate treatment of animal wastes."

Graham and his colleagues collected flies and samples of poultry litter from poultry houses along the Delmarva Peninsula, a coastal region shared by Maryland, Delaware and Virginia that has one of the highest densities of broiler chickens per acre in the United States. The analysis by the research team isolated antibiotic-resistant enterococci and staphylococci bacteria from both flies and litter. The bacteria isolated from flies had very similar resistance characteristics and resistance genes to bacteria found in the poultry litter.

Flies have ready access to both stored poultry waste and to poultry houses. A study by researchers in Denmark estimated that as many as 30,000 flies could enter a poultry house over the course of a six-week period.

Source: Johns Hopkins University Bloomberg School of Public Health

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