r fight them. Often working with UF College of Veterinary Medicine associate professor Klibs Galvao, Jeong challenged dogma concerning which uterine bacteria are responsible for causing metritis.
Jeong and Galvao’s teamwork revealed that applying chitosan nanoparticles to the infected uteri of cows drastically altered the microflora to a healthier composition. The particles were effective against pathogenic Fusobacteriaceae and Bacteroidaceae, both of which are associated with acute infectious processes and are resistant to penicillin-based antibiotics.
Jeong and his collaborator, Klibs Galvao, at a dairy cow research center where the pair are investigating novel ways of treating drug-resistant infections in food animals.
A recent $460,000 grant from the USDA National Institute for Food and Agriculture brings Jeong’s funding sum close to $1 million for investigating chitosan nanoparticles as a next-gen antimicrobial. His newest phase of inquiry will examine how to attach the best broad-spectrum antibiotics and drug extenders to chitosan nanoparticles to deliver a three-pronged infection-fighting punch directly to infection sites.
“We are very excited about testing this combination therapy,” Jeong says. “Medical doctors don’t have many antibiotics in reserve, so they are beginning to use two or three different antibiotics together in combination to fight highly resistant infections. My lab is taking this idea but repurposing it within the chitosan nanoparticle framework to bring a combination of drugs right into the uterus of cows infected with metritis.”
KC Jeong with Zhengxin Ma, a post-doctoral researcher, looking at a nematode, Caenorhabditis elegans, using a microscope.
The goal is to investigate how to amplify the antimicrobial properties of chitosan nanoparticles by coupling them with two other agents used to fight antibiotic resistant bacteria: third generation cephalosporin antibiotics and β-lactamase inhibitors. Cephalosporin antibiotics are one of the best broad-spectrum antibiotics on the market today, but drug-reistant bacteria threaten their usefulness. Jeong intends to test if combining them with specific nanoparticles will extend their effectiveness.
“Our work is innovative and significant because outcomes of this project are expected to lead to practical, effective new treatment options using nanotechnology,” Jeong says. “Overall, we expect that development of the new, value-added nano-antimicrobials will help improve animal and human health.”
While the trend amongst locavores is “farm to table,” Jeong’s research takes him on a less traveled path from laboratory to farm and back again. A significant part of his research agenda has focused on learning how beef cattle acquire pathogenic E. coli and antibiotic resistant bacteria.
“Our findings show that even animals grown without exposure to antibiotics, animals that have no history of antibiotic use in their feed or for treating infections, they have some baseline of antibiotic resistant bacteria in their gastro-intestinal tracts,” Jeong says. “Which led us to ask, ‘How did it get there?’” That seemingly simple question has led to more than $2.2 million in funding for his research between 2015 and 2020 from the U.S. Department of Agriculture.
Often working with EPI Director John G. Morris, and EPI researchers Judith Johnson and Volker Mai, Jeong’s team sampled a network of northcentral Florida farms to tease out whether antibiotic-resistant bacteria found in grass-fed cows originates in the environment (soil or water), or if it is a natural component of healthy cows’ intestinal microbiota. They identified nine bacterial isolates resistant to cefotaxime (a type of cephalosporin), six of which were identical to those found in people, and many of which also harbored high levels of multi-drug resistance.
Another of Jeong’s studies revealed that beef cattle, sampled every three months after birth, are colonized with Shiga toxin-producing E. coli within their first year of life. This is a particularly virulent strain of E. coli, and learning how it gets into cows