mples. Cefotaxime-resistant bacteria (CRB) in the cows’ feces ranged from a prevalence per farm of 21 to 87.5 percent.
Due to the wide range in occurrence of CRB from farm to farm, Jeong suspects that husbandry methods were influencing the presence of CRBs in these cattle. Further analysis revealed that when cows’ water troughs were cleaned regularly, they tended to have among the lowest CRB counts of any samples in the study, and farms with fewer than 500 cows had a far lower prevalence of CRB than farms with greater numbers of cattle.
“A lot of my research can seem very disparate at first glance,” Jeong says. “But it is all connected under the umbrella of the one health concept, the idea that animal health and people health is connected. It is my hope that we can learn how to reduce harmful bacteria in food animals, to not only increase the safety of our animal foods, but also to increase our own human public health.”
How did antibiotic-resistant bacteria get into our soil?
Consider that bacteria are the most abundant microorganisms in soil, and that a single gram of backyard dirt may contain billions of these "bugs." There are many different types of bacteria which have evolved over eons to survive against predators such as other bacteria or fungi. They produce all kinds of materials to kill the “other guys,” which is where our modern arsenal of antibiotics come from. One of the self-defense survival tools bacteria have evolved is production of the extended-spectrum beta-lactamase (ESBL) enzyme — which protects them from having their cell walls destroyed by naturally-occurring antibiotic substances produced by other bacteria. As a side effect, ESBL-producing bacteria just happen to be mucking up modern medicine, because microorganisms that can emit this substance are resistant to many different types of antibiotic drug therapies — including penicillins and cephalosporins.
Written by DeLene Beeland; All photos by Tyler Jones/IFAS. Special thanks to KC Jeong for his time.
Read KC Jeong’s EPI profile here.
This article draws on the following published literature:
Reduction of Escherichia coli O157:H7 shedding in cattle by addition of chitosan microparticles to feed. Appl Environ Microbiol. 2011 Apr;77(8):2611-6. doi: 10.1128/AEM.02587-10. Epub 2011 Feb 18.
Underlying mechanism of antimicrobial activity of chitosan microparticles and implications for the treatment of infectious diseases. PLoS One. 2014 Mar 21;9(3):e92723. doi: 10.1371/journal.pone.0092723.
Chitosan Microparticles Exert Broad-Spectrum Antimicrobial Activity against Antibiotic-Resistant Micro-organisms without Increasing Resistance. ACS Appl Mater Interfaces. 2016 May 4;8(17):10700-9. doi: 10.1021/acsami.6b00894.
Application of chitosan microparticles for mitigation of Salmonella in agricultural water. J Appl Microbiol. 2017 Nov;123(5):1346-1358. doi: 10.1111/jam.13566.
Engineering of chitosan-derived nanoparticles to enhance antimicrobial activity against foodborne pathogen Escherichia coli O157:H7. Carbohydr Polym. 2018 Oct 1;197:623-630. doi: 10.1016/j.carbpol.2018.06.046.
Comprehensive in vitro and in vivo risk assessments of chitosan microparticles using human epithelial cells and Caenorhabditis elegans. J Hazard Mater. 2018 Jan 5;341:248-256. doi: 10.1016/j.jhazmat.2017.07.071. Aug 1.
Quantifying known and emerging uterine pathogens, and evaluating their association with metritis and fever in dairy cows. Theriogenology. 2018 Jul 1;114:25-33. doi: 10.1016/j.theriogenology.2018.03.016.
Application of chitosan microparticles for treatment of metritis and in vivo evaluation of broad spectrum antimicrobial activity in cow uteri. Biomaterials. 2016 Dec;110:71-80. doi: 10.1016/j.biomaterials.2016.09.016.
Identification and Characterization of Cefotaxime Resistant Bacteria in Beef Cattle. PLoS One. 2016 Sep 19;11(9):e0163279. doi: 10.1371/journal.pone.0163279.
Colonization of Beef Cattle by Shiga Toxin-Producing Escherichia coli during the First Year of Life: A Cohort Study. PLoS One. 2016 Feb 5;11(2):e0148518. doi: 10.1371/journal.pone.0148518.
Colonization 