Escherichia coli (E. coli) infection continues to be a challenge in the nursery, causing morbidity and mortality in weaned pigs. Antimicrobial-resistant E. coli is becoming a prevalent concern as multi-drug treatments are not yielding successful results, explained Rachel Retterath, a second-year student in the University of Minnesota College of Veterinary Medicine, at the Allen D. Leman Swine Conference.
One alternative treatment of E. coli is to acidify the drinking water to decrease and prevent the growth of E. coli. Previous research shows that E. coli is least likely to colonize in a pH between 4 and 5.
“I wanted to find a specific pH value for producers to target,” she says. “With antimicrobial resistance on the rise, it is important that we are working on prevention strategies to mitigate the effects of these diseases and outbreaks. Therefore, if a flow is known to have E. coli, we can give them a concrete target to aim for with water acidification.”
Her research project consisted of finding the inhibitory pH point for E. coli. This involved making solutions of different pH levels: 4.0, 4.2, 4.4, 4.6, 4.8, and 5.0. She completed the project twice for accuracy and confirmed the levels using a pH meter.
Then, she incubated these and performed a serial dilution on each pH level before plating three different dilutions and incubated the plates. After incubation, she was able to quantify and visualize surface growth of each plate. This showed that a pH of 4.0 yielded no surface growth, while all other levels had significant amounts of growth.
“My biggest takeaway from this project is that there are many other areas we can continue to research to help our industry decrease antimicrobial resistance,” Retterath says.
She hopes her research can help producers by giving them a specific target to use when acidifying drinking water for inhibiting E. coli growth.
Retterath was one of seven students competing for the 2024 Morrison Swine Innovator Prize.
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