Researchers in a joint study from Kansas State University and North Carolina State University have discovered a high prevalence of antibiotic-resistant bacteria in insects on two hog farms in Kansas and North Carolina.

The study reveals scientists isolated entercoccus bacteria from the digestive tract of house flies and the feces of German cockroaches and pigs.

Kansas State researchers commented entercocci were common from all three sources and frequently carried antibiotic resistance genes.

But University of Minnesota epidemiologist Randall Singer, an expert on antibiotic resistance, says there is nothing new in reporting that insects carry antibiotic-resistant bacteria mechanically and in their digestive system.

Singer stresses the findings in the study do not establish any relationship between antibiotic use in agriculture and the selection for resistance.

“It has been known for a long time that insects can carry the bacteria they contact and ingest on farms. Sometimes these bacteria are resistant to antibiotics,” Singer says. Importantly, the study says nothing about the relationship between antibiotic use and antibiotic resistance because antibiotic usage over time in these herds wasn’t even measured. The antibiotic resistance they observed is very common. They didn’t identify some new resistance pattern or some new resistance gene. They found some very common resistance patterns within entercocci.”

For agriculture, the lesson is simply that this study confirms the need for insect control on farms as a critical step in controlling the threat of disease, Singer says.

“We have been pushing insect control for a long time, and this study shows us again why insect control is important. While this study supports the already known fact that insects can carry and potentially disseminate antibiotic-resistant bacteria, it says nothing about the development of antibiotic resistance in pigs.”