TV stations find MRSA in retail pork in Pacific Northwest

In the comments, Coilin Nunan of the UK's Soil Association (which published the wonderful 2007 report MRSA in Farm Animals and Meat report) calls attention to a report that I also spotted over the weekend.

A network of TV stations in Washington, Idaho, Oregon and California did a joint report in which they bought 97 packages of ground pork or pork cutlets and sent them to a laboratory for testing. The lab found that three of the packages, all ground pork, contained MRSA.

I believe this is the first time anyone has found (or, perhaps, looked for) MRSA in retail pork in the US. You'll remember that MRSA ST 398 has been found in meat in Canada and Europe, and in hospital patients in Scotland and the Netherlands, and in pigs in Iowa; and MSSA ST 398 in humans in New York City.

There are some important unanswered questions about this report:

• We aren't told the strain. If it's ST 398, that would be information on the spread of ST 398 in the US. If it's USA300, on the other hand, it could be contamination from an infected or colonized human, perhaps someone in the preparation chain.
• We aren't told the provenance of the pork. Was it bought from a variety of markets, or one chain of supermarkets that might have one regional supplier? Was it organic v. conventional? Small-farm versus feedlot?
• We can't draw any broad conclusions from this. I am a poor biostatistician, but to me, this is purely a convenience sample. (If anyone disagrees with me, please weigh in.) In other words, it's one data point. It says: There is MRSA in these packages of pork — which is an important piece of information — but it doesn't say: 3% of all US pork contains MRSA.

Also, while the written version of the report that I linked above isn't bad, overall, it contains one significant error. It says:

This drug-resistant bacteria is already responsible for more deaths in the US than AIDS. What makes MRSA so potentially dangerous is the bacteria can cause sickness just by touching it.

Well, not exactly. The concern with MRSA in meat is that, if you handle it without strict cleanliness, you might become colonized with the bacteria. That is not at all the same as developing a MRSA infection, much less the invasive MRSA the first sentence of that quote refers to. And yes, colonization can lead to infection. But to say that touching MRSA-contaminated meat will inevitably cause an invasive MRSA infection is alarmist.

I'm assuming the stations undertook this because it is sweeps month. (For those who have so far been spared the internals of TV news, "sweeps" are months — usually February, May, July and November — when stations' audiences are measured to determine market rank and advertising rates. Because it is in the stations' interest to attract as much audience as possible during those months, sweeps is usually when news stations run big investigative projects.) Interesting that they chose this topic. I think we can take this as an indicator — again, just one data point, but an interesting one — of emerging US concern over MRSA in meat.