CAFO Farms Boost Multi-Drug Resistant Bacteria, Study Says

A CAFO discharge to a canal. Credit: IdahoCARE, Flickr

CAFOS, aka concentrated animal feeding operations and factory or mega farms, are known for water pollution. What that pollution does, beyond being disgusting, is still being studied. The latest finding shows multi-drug resistance is more than three times greater near CAFOs than in agricultural streams not impacted by the farms.
The CAFO research, from Eastern Michigan University's Center for Aquatic Microbial Ecology, was published recently in the Water, Air, & Soil Pollution journal. Oh, and there's more: The researchers found that sites near CAFO farms had poor water quality, with elevated total phosphorus and turbidity. And multi-drug-resistant bacteria were significantly more common at sites impacted by CAFO farms.

"Our results indicate that CAFO farms not only impair traditional measures of water quality but may also increase the prevalence of multi-drug-resistant bacteria in natural waters," according to an abstract.

As for the "three times" finding, the researchers found that the proportion of multi-drug resistance at "agriculturally impaired" sites near CAFOs was 41.6%, or almost three times greater than that at "agriculturally unimpaired sites" away from the big farms.

Speaking of big farms, six of 10 sites examined in the study were located near an agricultural area in Hudson, Michigan. That area is home to a dozen "livestock factories," according to Environmentally Concerned Citizens of South Central Michigan, which has a website with the catchy address of The group keeps track of environmental violations by factory farms in Michigan, where there's an ongoing struggle between state environmental regulators and bad actors in the agricultural industry.

What does the latest study mean? That will probably be debated for some time, especially with comparisons between discharges from farms to faulty septic systems and other "nonpoint sources."

The researchers conclude: "The risk to human and animal health posed by the high incidence of antibiotic resistance and gene transfer is unknown. Traditional measures of chemical and biological water quality do not appear to be direct surrogates for detection of the prevalence of antibiotic resistance ... We echo previous suggestions ... that testing for antibiotic resistance genes in bacterial strains become part of the standard methods for examining and regulating water quality and wastewater discharge in areas at high risk for pollution from human and animal waste."

Another idea: Moving back to more traditional forms of farming.

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