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ARS Home » Midwest Area » Bowling Green, Kentucky » Food Animal Environmental Systems Research » Research » Publications at this Location » Publication #380617

Research Project: Developing Safe, Efficient and Environmentally Sound Management Practices for the Use of Animal Manure

Location: Food Animal Environmental Systems Research

Title: Prevalence and detection of antimicrobial-resistant bacteria in dairy cattle farm environments in East Tennessee

item ENSERMU, D - University Of Tennessee
item VANCUREN, M - University Of Tennessee
item GILLESPIE, B - University Of Tennessee
item Agga, Getahun
item D'SOUZA, D - University Of Tennessee
item OKAFOR, C - University Of Tennessee
item KERRO, DEGO - University Of Tennessee
item GELALCHA, B - University Of Tennessee

Submitted to: Conference Research Workers Disease Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 11/12/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The extensive use of antimicrobials in dairy farms could lead to the emergence and spread of resistant bacteria in the farm environments. Monitoring of antimicrobial-resistant (AMR) bacteria in dairy farms is helpful to implement appropriate control and mitigation measures. The objective of this study was to determine the prevalence of AMR representative Gram-positive (Enterococcus and Staphylococcus species) and Gram-negative bacteria (Escherichia coli) and Salmonella spp) in four dairy cattle farms in East Tennessee. Four different sample types (bulk tank milk, pooled feces from farm floor, dairy manure fertilized soil, and prairie soil; n=40 for each sample type) were collected from dairy cattle farms. The bacteria were isolated and tested for resistance against tetracycline, cefotaxime, nalidixic acid, ceftiofur, and erythromycin. A subset of phenotypically resistant and susceptible isolates was tested for the presence of a resistance gene using each gene primer pairs by PCR.Results All four bacterial isolates displayed the highest prevalence of resistance to tetracycline (ranges from 17.1 - 79.5%) than to other antimicrobials. Almost half (49%) of the bacterial isolates were resistant to at least one of the antimicrobials. Most of the resistant bacterial isolates 74% (70/94) were isolated from fecal samples. E. coli showed the highest prevalence of resistance (79.5%) compared to the other three bacteria. Both E. coli and Salmonella spp showed the highest resistance to tetracycline, followed by cefotaxime. PCR result showed the presence of extended-spectrum beta-lactamase (blaCTX-M), tetA, and tetB resistance genes in E. coli; and tetM and ermB in Enterococcus spp. The results of this study indicated that antimicrobial-resistant bacteria are widespread in dairy cattle farm environments. Thus, further investigation to determine the extent of AMR and factors driving the emergence and spread of resistance in dairy farms is of paramount importance.