Last week’s 800,000-pound beef recall, in response to an outbreak of antibiotic-resistant strain of Salmonella, now found in 11 states, is yet another warning about the potential dangers of pervasive non-therapeutic antibiotic use in livestock. A recent study by the United States Department of Agriculture’s Agricultural Research Service (ARS) found that the prevalence of Salmonella in beef might be greater than was previously thought. The ARS estimated that the total Salmonella prevalence in ground beef in packing plants is 4.2 percent, which is far greater than FSIS’s 2.4 percent estimate. The same study found a 0.6 percent prevalence of antibiotic-resistant Salmonella. According to the Pew Campaign on Human Health and Industrial Farming, out of the nearly 1.4 million in the U.S. who contract Salmonella annually, approximately one fifth, or 272,000, of those infections are antibiotic-resistant. Over a third of these are multi-drug resistant, with resistance to five or more drugs. Of the 2.4 million Campylobacter infections in the U.S., roughly half are resistant to at least one antibiotic and nearly fourteen percent of those cases are resistant to two or more drugs. Widespread non-therapeutic use of antibiotics is often cited as a key factor in the development of antibiotic-resistance, though many experts admit more research is needed in the area. The Pew Commission on Industrial Farm Animal Production recently released a comprehensive report looking at these issues. Robert P. Martin, the executive director of the Commission, cited a confluence of factors that likely contribute to drug-resistant Salmonella in beef. Martin explains that dairy cows are being pulled out of the dairies and into the slaughterhouses at a more rapid rate than usual in an effort to control sagging milk prices. Dairy calves are usually given a hefty dose of antibiotics in their infant formula. The antibiotics help them grow and help to ward off bacterial infections, but it can cause the cows to develop resistant Salmonella in their gut. When the cow is eventually slaughtered, bacteria from its intestine can become mixed in with the ground beef, resulting in an antibiotic-resistant Salmonella burger. Martin points out that even though dairy farmers do not routinely use antibiotics on their cows while they produce milk–the FDA tests for antibiotic levels and milk will be thrown out if antibiotics are found–the protocol with young calves is enough to fuel the problem. According to Martin, “the chances are pretty high that this is how [the current outbreak] happened.” Though, Martin pointed out, the routine use of antibiotics on beef cattle, especially during the time spent at massive feedlots just prior to slaughter, also contributes to the development of resistant pathogens like E. coli, Campylobacter, and Salmonella. Photo courtesy CDC/ Dawn Arlotta.