A few weeks ago I wrote a post highlighting the book, Superbug by Maryn Mckenna. The book tracks the emergence of antibiotic-resistant MRSA and claims that the heavy use of antibiotics in industrial animal agriculture has contributed to the rise of these resistant strains of bacteria.

Mckenna has an article at Wired.com today that reports on a new scientific study on the presence of drug-resistant bacteria in meat for sale in stores. She reports:

A team of researchers from Arizona bought meat and poultry in five cities across the United States, tested them for bacteria, and found this: 47 percent of the samples contained the very common pathogen Staphylococcus aureus, and 96 percent of those isolates were resistant to at least one antibiotic. Of more concern: 52 percent of those staph isolates were resistant to at least three antibiotics that are commonly used in both veterinary and human medicine.

That is: Roughly one in four packages of meat and poultry from across the US contained multi-drug resistant staph.

Here's the breakdown of how different types of meat compared:

Among the types of meat tested, turkey carried the most resistance, with 77 percent of the meat samples showing at least some; that was followed by pork (42 percent), chicken (41 percent) and beef (37 percent). Interestingly, it wasn’t all the same staph. Though there was a great diversity of staph types, each animal species seemed to carry mostly one sequence type or strain of staph: ST1 in pigs, ST5 in chickens and ST398 in turkey.

Perhaps the most important finding in the study is that the source of the bacteria was not human contamination, rather the bacteria came from the animals themselves. Mckenna quotes study team member Lance Price:

“There’s an important second point: We found that each of the meat and poultry types had their own distinctive staph on them. That provides strong evidence that food animals were the primary source of the resistant staph. The source wasn’t human contamination of the meat at slaughter, or when it was packaged for retail sale.”

This is an important data point in the debate about the impact of antibiotic use in raising farm animals. The Ag. community has argued for years that no one has been able to prove a link between such use and the emergence of drug-resistant bacteria that is harmful to humans. The evidence is mounting that concentrated animal operations are not only bad for animals, but they are bad for humans as well.

Go here for a previous post on safety issues with America's meat supply.

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