Disease resistance: down on the farm

Our recent post has been about India doing foolish things with antibiotics.   They at least were treating people.  Now we show that the antibiotic practices in agricultural are spreading resistances across species.

Seven years ago, Dutch researchers were finding drug resistant staff strain in toddlers. What was odd, was that it was resistant to a drug that it likely never would have faced. Further research connected it to the pig-farms where they were living. The pigs were on a regular basis being given lots and lots of antibiotics to help fatten them up, and keep them healthy. The resistance to the antibiotic had crossed over from the pigs.

In a study that received very little cooperation from the public, taking very minimal samples from a community in Iowa, they were able to show similar results.  The big difference was the immunities involved.

Farm Antibiotics: ‘Pig Staph’ in a Daycare Worker

Maryn McKenna, Wired, 9 May 2011 siting: Livestock-associated Staphylococcus aureus in Childcare Worker, CDC Vol. 17 No. 4, April 2011

From that first discovery unrolled the microbiological equivalent of a car-chase scene, complete with unpredictable turns, skids around corners, and unexpected dead ends. Researchers have identified ST398 in animals, people and retail meat in most of the EU; in pigs, farmers and hospital patients in Canada, and in pigs and a few farm workers, and most recently supermarket meat, in the United States. (You’ll find a long archive of posts on ST398, and more here.)

The group, headed by Tara Smith at University of Iowa, report in the April issue of Emerging Infectious Diseases that they got permission to conduct MRSA surveillance in a daycare facility in Iowa....There’s an important detail in the Iowa team’s results. Technically, this drug-resistant ST398 was not MRSA. That is, it was not resistant to beta-lactam antibiotics: semi-synthetic penicillins such as methicillin (the “M” in MRSA) and cephalosporins. It was resistant to other drug classes, including erythromycin.

This is not unusual. Remember the big news from a couple of weeks back, about one in four samples of supermarket meat being contaminated with drug-resistant staph. Most of that staph — some of which was ST398 — also was not MRSA, that is, not resistant to the beta-lactam class. In people, the biggest single finding has probably been the discovery a few years ago that people from a few villages in the Dominican Republic were carrying ST398 with them as them moved back and forth between the Caribbean and New York City. The single most poignant finding is probably the discovery last year that an ST398 with a similar pattern to this Iowa one killed a French child.

At times you would almost think they are trying to kill us off.  Of course if the zombie-strain crosses over, presumably we would still be able to show up for work.

Pulsed-field gel electrophoresis of Staphylococcus aureus (from here)