Prevalence and Spatial Variation of Antimicrobial-Resistant Commensal Bacteria in Poultry and Cattle Farms

Maureen Syokau Nzomo, Tennessee State University


The use of antibiotics in food-producing animals has been a significant cause of the emerging and progressively antibiotic resistance in humans. This study evaluated the prevalence and spatial variation of antimicrobial-resistant profiles of Escherichia coli, Klebsiella, and Enterococcus in cattle and poultry farms in Tennessee and Alabama. The bacteria were subjected to susceptibility testing against 12 clinically relevant antibiotics by Kirby-Bauer disk diffusion. Using ArcGIS map software, maps showing antimicrobial-resistant profiles in the different locations on the cattle and poultry farms were generated. To assess the best management practices by cattle and poultry farmers, surveys were administered and data collected from 26 and 29 farms in Alabama and Tennessee respectively. Overall, Enterococcus (80%), E.coli (55.6%) and Klebsiella (22.8%) were significantly prevalent at (p< 0.05) in cattle and poultry farms. Generally, the highest resistance (p<0.05) was exhibited to erythromycin, nalidixic, ampicillin, and vancomycin at (80-100%) in soil, water, and manure. Nevertheless, all the bacteria showed relatively low resistance (p>0.05) to doxycycline, chloramphenicol, and gentamicin at (0-50%) in all the sample types. Notably, in all the seasons, the bacteria were multi-drug resistant as displayed by the AMR patterns on the maps. The multiple antibiotic resistance (MAR) index value for the three commensal bacteria range was between 0.25 to 0.92 in Tennessee and 0.33 to 0.83 in Alabama. However, none of the bacteria had a MAR index value of 1.0 to indicate resistance to all the antibiotics tested. The survey analysis indicated that 82.8% and 92.4% of farmers in Alabama and Tennesee respectively used antibiotics to treat sick animals and prevent diseases. These data reveal that cattle and poultry farms harbor antimicrobial-resistant bacteria which could potentially be transmitted to humans. Consequently, there’s a need to implement antimicrobial stewardship programs to educate farmers on antibiotics use and the application of good agricultural practices on their farms.

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Recommended Citation

Maureen Syokau Nzomo, "Prevalence and Spatial Variation of Antimicrobial-Resistant Commensal Bacteria in Poultry and Cattle Farms" (2021). ETD Collection for Tennessee State University. Paper AAI28650999.