May 5, 2016


In his acceptance speech for a 1945 Nobel Prize, Dr. Alexander Fleming, co-developer of penicillin, warned that overuse of the life-saving drug could lead to a bacterium’s ability to withstand the killing effects of antibiotic drugs.

According to the World Health Organization (WHO), we have reached the point of antibiotic resistance, resulting in a major public health threat in every region of the world. For that reason, in May 2015, WHO endorsed a global action plan “to tackle antimicrobial resistance, particularly antibiotic resistance, the most urgent drug-resistance trend.”

Many are aware of efforts by hospitals to reduce transmission of microorganisms, dubbed “super bugs,” because they are resistant to many treatments, even to drugs of last resort.

Mark D. Sobsey, PhD, Kenan Distinguished Professor of environmental sciences and engineering, has found these antimicrobial-resistant organisms in discharges of waste from industrial agricultural operations, particularly hog farms, and in nearby waterways in North Carolina, as well as in hospital and community raw sewage.

“We’re seeing the same problems in animal agricultural waste as we see in hospital waste, where we know that antibiotic use is very high,” says Sobsey.

“It was typical to find that between 10 percent and 100 percent of bacteria in the animal waste is resistant to antimicrobials,” he says. “They were not only resistant to one antimicrobial, but multiply resistant to as many as six or seven, meaning there were few to which they were not resistant.”

Sobsey, along with colleagues at Colorado State University, and in Nicaragua, Singapore and Mexico City, are finding the same bacteria throughout the world in environmental waters affected by these types of waste sources.

He says the best way to determine the origins of the bacteria – and work to minimize them – is for researchers to determine exactly which contaminants are in a given environment.

“While a lot of work has been done on antimicrobial-resistant bacteria in the environment, not enough attention has been given to those most resistant and of highest priority,” says Sobsey. “Where are the bacteria coming from? What hotspots do we suspect? How do we decide the best approaches to minimize their release from those sources?”

Sobsey is continuing the work, but finds it difficult to obtain funding for it.

Following Hurricane Floyd in 1999, which caused environmental devastation resulting from flooded waste lagoons on industrial hog farms, the State of North Carolina declared a moratorium on expansion of such farming operations. Two of the largest corporations with operations in the state supported a $13 million study of pathogens, odorants and excess nitrogen – and potential solutions to such contamination from industrial hog farming.

As Sobsey explains, even though the study produced recommendations for cost-effective ways to reduce the levels of environmental impacts, the companies chose not to implement any of the methods in North Carolina. Instead, they expanded their operations in states without a moratorium.

–Elizabeth Witherspoon


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Carolina Public Health is a publication of the University of North Carolina at Chapel Hill Gillings School of Global Public Health. To view previous issues, please visit sph.unc.edu/cph.