A new study of pigs who are given low-dose antibiotics, as at factory farms, shows yet again that any of us who are still eating these animals should be seriously concerned for our own health – not to mention theirs.
Discovery News explains that just two weeks of low-dose antibiotics boosted the number of E. coli in the guts of pigs and the bacteria had more drug-resistant genes:
After giving pigs a low-dose of antibiotics for just two weeks, researchers saw a drastic rise in the number of E. coli bacteria in the guts of the animals. And those bacteria showed a large jump in resistance to antibiotics.
The particular strain of E. coli detected in the study was not pathogenic to pigs or humans. But the results add to concerns that regular use of antibiotics in farm animals could spread dangerous and drug-resistant varieties of bacteria throughout the environment and into our food and water.
Pigs and other animals like cows and chickens are given antibiotics throughout their short lives in order to ward off the rampant infection that’s inevitable in these Concentrated Animal Feeding Operations (CAFOs), as they’re known in the trade. The antibiotics also cause the animals to grow faster.
But studies have long shown that antibiotic use leads to an increase in antibiotic resistance in animals taking the drugs as well as in people working on the farms where those animals live. Even when farmers stop using the drugs, resistance persists for years, as mothers pass their drug-resistant flora down to their offspring for generations.
The pigs who were studied in this laboratory experiment were divided into two groups – one received the daily antibiotics (as at a factory farm) and the other did not.
Within two weeks, the proportion of a group of bacteria called Proteobacteria had increased from one percent to 11 percent in the poop of the medicated pigs. E. coli accounted for the majority of that rise.
In other words, the antibiotics actually caused a rise in bacteria. That’s because the continued medication enables new adaptations of E. coli to become increasingly resistant to the antibiotics.
Treatment with antibiotics produced a detectable rise in resistance, and not just to the drugs the pigs were eating. Genes also flourished that could resist other kinds of antibiotics as well, and researchers are now puzzling over the details of how using just a few antibiotics might lead to multiple drug resistances.
The study is reported in the Proceedings of the National Academy of Sciences, where the researchers also discuss other potential ways of coping with bacteria at factory farms. But the best way we can avoid ingesting both the increasingly resistant forms of E. coli and also the low-dose antibiotics is to not eat any kind of meat from factory farms.