Latest Study Finds More MRSA in Grocery Pork, Even When it’s Antibiotic-Free

A recent study by the University of Iowa’s School of Public Health that discovered a dangerous prevalence of antibiotic-resistant bacteria lurking in pork on grocery store shelves could lead to an even more dangerous conclusion.

The study found that the incidence of methicillin-resistant Staphylococcus aureus (MRSA) bacteria in 36 grocery stores in three states (Iowa, Minnesota, and New Jersey) was considerably higher than what had previously been assumed. Of the 395 samples collected and tested in the study, 26 of them, or 7 percent contained MRSA. That’s about one out of every 15 samples.

The other interesting finding was that the level of MRSA was about the same in meat raised without antibiotics as meat raised using the more conventional industrial methods. This finding is counter-intuitive and must be interpreted with caution.

Maryn McKenna, author of the book Superbug,  becomes alarmed when she hears indifferent reactions to the study, or worse yet, those that use the results to undermine the push to eliminate the widespread use of antibiotics in otherwise healthy animals.

According to McKenna, this is a faulty conclusion and a dangerous one to be spreading, especially at a time when the FDA appears to be backing off on their commitment to regulate anti-biotic use in livestock.

Her take on the question was more nuanced as she described in this interview in Grist.

My takeaway is that, in its underlying data, the study proves what campaigners against ag[ricultural] antibiotic use keep saying: that once you use antibiotics indiscriminately and drive the emergence of resistant organisms, you have no way of predicting where that resistance DNA will end up.

The problem with massively dispensing livestock antibiotics stems from the same faulty logic behind genetically modified organisms (GMOs). Treating living organisms, whether they are  staphylococcus bacteria, insects or weeds, as industrial nuisances that can be manipulated at will, fails to take into account the fact that biological organisms are continuously evolving, especially when they are placed under stress.

As they exist right now, industrial meat operations are an unsustainable house of cards. Take away the use of pre-emptive antibiotics, the only thing keeping these animals alive in the unsanitary disease-ridden environments they are held in, and the whole system will collapse. And yet if we continue dispensing millions of pounds of antibiotics to livestock, which are then handled by human workers, the prevalence of these and other new resistant strains of bacteria are bound to keep emerging and the likelihood of them infecting people will keep increasing.

Recent studies find that the bacteria are transmittable between animals and humans. It’s true that the strains that infect pigs are not the same as those that infect humans, though both strains were found among the samples collected in the Iowa study and in fact most of it was not the livestock kind. Incidentally, pigs bound for slaughter are not currently tested for MRSA in the US (though they are in Denmark where they found that 13 percent of all pigs test positive for MRSA).

The National Pork Board quickly got on the defensive, pointing out that that not all MRSA strains are harmful to people. In general, livestock strains of the bacteria show little effect on people.

But Tara Smith, lead author of the Iowa study, came right back with, "These are common human strains," Smith said. "These strains do cause infections in people."

Jennifer Koeman, the National Pork Board’s Director of Public Health claims that, "the prevalence is comparable or less than seen in other countries," as if to suggest that makes it okay.

Careful examination of the data, according to McKenna, shows that the first MRSA that went from pigs to humans was tetracycline resistant. Tetracycline is a drug that is rarely used to treat MRSA in humans though it is routinely given to livestock. So these organisms likely emerged as the result of the preventative dosing the animals were given.

“Once you stimulate the emergence of resistant organisms by using antibiotics in inappropriate ways on farms, some percentage of those organisms — exactly how much we don’t know because we’re not allowed to measure on farms — end up in the farms’ manure lagoons. And then they blow off in dust or get into waste water or otherwise end up in the environment of the farm.

From there they get carried off by the farm workers or they infect [other] workers. Those organisms then go all over the place. In the wake of this study, people were saying, ‘Since as much resistant bacteria is on meat without antibiotics, the whole concern about antibiotic use on farms is misplaced.’ That’s only true if you think that retail meat is the only place where the resistant organisms show up. But it’s not.”

No organic meat was included in the study.

The plain fact is that using antibiotics stimulates the emergence of potentially deadly resistant strains. What happens after that simply cannot be completely controlled.

On a final safety note, even though MRSA is killed by cooking, infection can occur from handling the meat if the bacteria should get on your skin or in your nostrils, so please remember to always use care and wash your hands after handling raw meat.

[Image credit: thornypup:Flickr Creative Commons]

RP Siegel, PE, is the President of Rain Mountain LLC. He is also the co-author of the eco-thriller Vapor Trails, the first in a series covering the human side of various sustainability issues including energy, food, and water. Now available on Kindle.

Follow RP Siegel on Twitter.