In an interesting article published online today, the author discusses the growing threat to the public health posed by the presence of methicillin-resistant Staphylococcus aureus (MRSA) in our food supply. See Stephanie Woodard, Concerns Over Superbugs in our Food Supply, available at www.msnbc.msn.com/id/31766160/ns/health-food_safety/ Although this threat is not new, nor are the warnings be raised about it, I thought it was worth raising the issue here in light of the article posted yesterday about Legislative efforts to restrict the widespread use of antibiotics in food animals. (To read that article, see here: www.foodpoisonjournal.com/2009/07/articles/food-poisoning-watch/antibiotic-use-in-food-animals-addressed-by-house-committee/#comments ) I think that one passage in particular is worth paying attention to, because it shows just how far we need to go to both understand this growing risk, but to stop it.
Until recently, the CDC has acknowledged the presence of MRSA in meat but downplayed the danger. In 2008, then CDC director Julie Louise Gerberding, MD, MPH, wrote that foodborne transmission of MRSA is "possible" but, if it happens, "likely accounts for a very small proportion of human infections in the US." Liz Wagstrom, DVM, assistant vice president of science and technology for the National Pork Board, agrees, saying that this kind of transmission would be extremely rare. Neither group could provide an estimate when queried by Prevention, but considering the high numbers of MRSA infections, even a tiny percentage could be a lot of people.
One reason the CDC and the National Pork Board must guess about transmission rates — and why we don’t know exactly how many MRSA-related infections occur — is that the federal government doesn’t collect data on MRSA outbreaks, says Karen Steuer, director of government operations for the Pew Environment Group. According to the US Government Accountability Office, there’s no testing for MRSA on farms. And the National Antimicrobial Resistance Monitoring System tests just 400 retail cuts of meat each month for four drug-resistant bacteria — which don’t include MRSA.
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Research done in the European Union is increasingly confirming the presence of MRSA in meat products. For example, in a study published in the CDC-journal, Emerging Infectious Diseases, researchers found 36 different strains of S. Aureus in 79 samples of meat, including two that were methicillin-resistant. See van Loo, et al. Methicillin-resistant Staphylococcus aureus in meat products, the Netherlands. Emerg Infect Dis [serial on the Internet]. 2007 Nov [Available from www.cdc.gov/EID/content/13/11/1753.htm Recently-published research has confirmed the same thing among pigs and pig farmers in the United States, finding MRSA present in nearly half of the pigs and pig farmers tested. See Smith TC, Male MJ, Harper AL, Kroeger JS, Tinkler GP, et al. (2009) Methicillin-Resistant Staphylococcus aureus (MRSA) Strain ST398 Is Present in Midwestern U.S. Swine and Swine Workers. PLoS ONE 4(1): e4258. Available from www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0004258
Dr. Tara Smith, the scientist that did the study that found MRSA so widely present in Iowa is on record as saying the federal government has a huge role to play in addressing this problem. "The studies should be expanded nationwide to examine hundreds of farms in Iowa and other swine-farming states and see how common MRSA is on a national level." Dr. Smith also states that here study is a real reminder of need for safe food handing and cooking procedures. As quoted, she states: "It’s likely that cooking will kill any MRSA present on the surface of meats, but anyone handling raw meats should be careful about cross-contamination of cooking areas or other food products, and should make sure hands are washed before touching one’s face, nose, lips, etc."
(Note: These quotations from Dr. Smith are from the an excellent blog-post on this same topic, which can be found here: blog.seattlepi.com/secretingredients/archives/160278.asp )