IAFP 2013: What Do We Know About Antibiotic Resistance?

Curbing antibiotic resistance in the food supply is a complex task, said Dr. Hua Wang, associated professor of food science and technology at Ohio State University, in her address at a symposium on antibiotic resistance at IAFP Monday. Wang and her colleagues are working on a nuanced solution to this nuanced problem by pinpointing the places in food production where resistance is most likely to appear and focusing preventive efforts there.

Wang presented her talk as a sort of state-of-antimicrobial-resistance address. First, without downplaying the threat of antibiotic resistance, she tried to provide some context:

"Pathogens account for a small amount of the microbial population," Wang said. "When talking about antibiotic-resistant pathogens, that number is even smaller."

When it comes to antibiotic-resistant (AR) pathogens in the food supply, that number gets even smaller. Narrow that to antibiotic-resistant pathogens that don't get cooked to death, and we've got a very small sliver of the overall microbial biomass.

But having a limited presence should not suggest AR pathogens don't pose a serious threat to public health and a challenge to food manufacturers. In fact, the presence of AR pathogens in food is accelerating, she said.

A recent study conducted by Wang and her colleagues found that commensal bacteria (the bacteria that hitches a free ride in your body without causing you harm) might greatly contribute to the spread of AR genes. Other studies have backed up that conclusion, Wang said.

"These studies show that antibiotic-resistant bacteria can persist even without direct exposure to antibiotics in the host's system," she said.

Scientists are having a hard time getting access to farms to study AR among livestock. Instead, Wang and her team chose to collaborate with the cheese industry to get access to production facilities where they could measure for AR along critical control points.

Once they found the points that made the biggest difference in the presence of AR microbes, they made a number of mitigation recommendations to the cheese industry. By following these recommendations, the industry removed problematic AR strains and reduced the AR gene pool "significantly," Wang said.

"It is important to recognize that prudent use of antibiotics does not mean a ban of use or not use," Wang said, "but knowing what, when, and how to use the antibiotics."

In another realm, scientists are finding that AR bacterial genes can be passed from the microflora of a mother onto those of her newborn child. Infants never directly exposed to antibiotics can be shown to harbor bacteria with AR genes immediately after birth.

Despite everything we know, Wang pointed out, AR emergence "is still a puzzle."

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