[The following is an exact transcript of this podcast.]

Seventy percent of all antibiotics in this country go to livestock like pigs and chickens. And concern is growing about drug-resistant bacteria that sprout up in crowded livestock facilities and may spread to humans. Now researchers suggest that a vector for that spread may be the common housefly.

Scientists from the Johns Hopkins Bloomberg School of Public Health collected samples of both flies and poultry litter at chicken houses along the Delmarva Peninsula. That's the region where Delaware, Maryland and Virginia meet up, and it has the highest concentration of what are known as broiler chickens in the U.S.

They isolated and analyzed antibiotic-resistant enterococci and staphylococci from both groups. The samples showed that the bacteria in both the flies and the litter have similar characteristics and genes for resistance. The researchers caution that they haven't shown conclusively that flies are in fact spreading the diseases. But more than 30,000 flies might enter a poultry house over six weeks. And flies are known to be vectors of viral and bacterial diseases such as cholera. Another study to add to the growing pile of research suggesting our cheap meat is not as cheap as it seems.

—Cynthia Graber 

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