Sugar solution fights infection in dairy cows just as well as antibiotics

The discovery has the potential to reduce reliance on antibiotics and ultimately help combat the growing threat of antimicrobial resistance in both humans and animals, said Adrian Barragan, associate research professor and extension veterinarian at Penn State and co-lead author on the paper.

The findings are particularly significant for the organic dairy industry where antibiotic use is restricted, he added, and may also pave the way for future studies in humans on the use of sugar-based formulations for uterine infections such as endometritis.

"The disease is an infection of the uterus that occurs after calving and it's one of the top diseases that affect dairy cattle in the United States," said Erika Ganda, assistant professor of food animal microbiomes at Penn State and co-lead author on the study. "We treat cows with antibiotics only when necessary to ensure their welfare, following strict withdrawal periods to prevent residues in milk. Minimizing antibiotic use helps reduce the risk of resistant bacteria that can impact farm workers, families and communities. Antimicrobial resistance in human and veterinary medicine is a growing public health concern, so the main goal of this research was to test an antibiotic-free alternative option against the current gold standard for treating this prevalent disease."

The study compared two treatments for a common uterine infection, called clinical metritis, that can lead to serious health problems for dairy cows. The condition is typically treated using systemic antibiotics, like ceftiofur, which are effective in treating the condition, but may contribute to the growing antimicrobial resistance in food-producing animals.

"We have been searching for alternative therapies that can effectively treat metritis without relying on antibiotics," Barragan said. "We asked two main questions when studying an alternative: Do the animals get cured with this treatment? And do treated animals have similar performance? Although the alternative treatment had the same clinical cure rate as the antibiotics, the answer wasn't as clear cut as expected since performance between treatment groups differed based on disease severity."

The study focused on using intrauterine dextrose, a sugar solution, as a possible alternative treatment. Dextrose has been extensively studied in animal and human clinical research for its ability to plasmolyze harmful bacteria, essentially the strong sugar solution pulls water out of the bacteria, causing them to dry out and die, Barragan explained. The approach had shown some promise in human wound healing, but previous studies in cattle yielded mixed results.

"We were hopeful that we would find positive results, but we were definitely not expecting to find that both treatments worked similarly for mild cases of metritis," Barragan said. "That was a very exciting discovery."

To investigate the effectiveness of dextrose, the researchers conducted a study on a dairy farm in central Pennsylvania. They enrolled 77 cows diagnosed with clinical metritis and randomly assigned them to one of two treatment groups: intrauterine dextrose or systemic ceftiofur. The researchers then monitored the cows' recovery and analyzed their uterine microbial communities using advanced DNA sequencing to better understand the overall health of their microbiomes.

Although the sample size was not ideal for assessing clinical cure rate, Barragan said, the results suggested that both treatments had similar clinical cure rates, meaning dextrose could be just as effective as antibiotics in treating mild metritis cases.

Additionally, the analysis of the cows' microbiomes revealed that dextrose does not significantly disrupt the bacterial balance of bacteria in the reproductive tract, unlike antibiotics, which can alter microbial communities and potentially impact the long-term health of the cow, Ganda explained.

Further research is needed to understand the full potential of dextrose as an alternative to antibiotic treatment, Barragan said, but one day that potential could even extend to treating humans.

"Our findings may be applicable for reproductive disease in human medicine," he said. "In fact, we were inspired by medical literature and sugar-based wound treatments for people."

The other Penn State authors on the paper are Jennine Lection, who earned a doctoral degree from Penn State and is currently an assistant professor at North Carolina State University; Emily Van Syoc, postdoctoral scholar; Asha Miles, former postdoctoral research associate who is currently a research geneticist at the U.S. Department of Agriculture (USDA); Julia Hamilton, undergraduate student; Marcela Martinez, research technologist; and Justin Silverman, assistant professor of statistics and of medicine and faculty fellow of the Institute for Computational and Data Science. Santiago Bas of the Germany-based feed company Phytobiotics Futterzusatzstoffe GmbH also contributed to the paper.

The USDA National Institute of Food and Agriculture and Hatch Appropriations, the Pennsylvania Department of Agriculture, and the National Institutes of Health funded this research.