You took my comment out of context. In their paper, which I quoted, the scientists admitted they don't know definitively where the staph came from. To then implicate the farms in a report for the general public when they don't have the scientific proof to back it up is indeed junk science.
And, yes, it's the law that each meat packing line be disassembled each night and sterilized. Besides my own personal knowledge of the meat industry, I've seen documentaries on it, including one episode of "Modern Marvels". You might also want to look at
http://www.foodsafetymagazine.com/article.asp?id=569&sub=sub1 and
http://www.beaverfish.com/index.php/services/meat-processing.html . What have you got to prove otherwise?
And you misread my original post. I never denied that animals are the source of bacteria. My point is that once an animal comes through the line with a specific bug with identifiable DNA, that particular bug can be spread by workers throughout the meat packing plant (gloves and aprons won't make any difference since they often contain blood and other liquids which can transmit bacteria), and hence show up in many different grocery stores. Another possible source I didn't mention originally are the trucks used to haul these animals to the meat packing plants. These aren't sterilized between different farm pickups, so a bug from one farm can contaminate the truck and any animals shipped on the truck afterwards. I am definitely NOT claiming that I know the source of the staph; I am just saying there are many plausible alternatives that the scientists who wrote the original paper haven't considered (which they themselves admitted). If you understand science at all, you will know you can't make claims of scientific proof until all possible alternatives have been examined and eliminated.
You are naive if you think it's easy to trace the source of an infection. Just look at the current E. coli scare in Europe (and previous ones here in the US). They still don't know the source of the outbreak. See
http://online.wsj.com/article/SB10001424052702304432304576369163252964714.html .
