AUTHOR=Gelalcha Benti D. , Gelgie Aga E. , Kerro Dego Oudessa 

TITLE=Prevalence and antimicrobial resistance profiles of extended-spectrum beta-lactamase-producing Escherichia coli in East Tennessee dairy farms

JOURNAL=Frontiers in Veterinary Science

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2023.1260433

DOI=10.3389/fvets.2023.1260433

ISSN=2297-1769

ABSTRACT=<sec><title>Introduction</title><p>The extended-spectrum beta-lactamase (ESBL)-producing <italic>Enterobacteriaceae,</italic> such as <italic>Escherichia coli</italic>, are emerging as a serious threat to global health due to their rapid spread and their multidrug-resistant (MDR) phenotypes. However, limited information is available regarding the prevalence and antimicrobial resistance (AMR) profile of ESBL-<italic>E. coli</italic> in the United States dairy farms. This study aimed to determine the prevalence and AMR pattern of ESBL-<italic>E. coli</italic> in East Tennessee dairy cattle farms.</p></sec><sec><title>Methods</title><p>Rectal fecal samples from dairy cattle (<italic>n</italic> = 508) and manure (<italic>n</italic> = 30), water (<italic>n</italic> = 19), and feed samples (<italic>n</italic> = 15) were collected from 14 farms. The presumptive <italic>E. coli</italic> was isolated on CHROMagar™ ESBL and confirmed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Antimicrobial susceptibility testing was performed on the ESBL-<italic>E. coli</italic> isolates.</p></sec><sec><title>Results and discussion</title><p>From 572 fecal and farm environmental samples, a total of 233 (41%, <italic>n</italic> = 572) ESBL-<italic>E. coli</italic> were identified. The prevalence of fecal ESBL-<italic>E. coli</italic> was 47.5% (95% CI: 46.2–49.2). The within-farm prevalence of ESBL-<italic>E. coli</italic> ranged from 8 to 100%. Recent treatment history with third-generation cephalosporins (3GC), cow parity ≥3, and calves were the independent risk factors associated (<italic>P</italic> &lt; 0.05) with fecal carriage of ESBL-<italic>E. coli</italic>. Overall, 99.6% (<italic>n</italic> = 231) ESBL-<italic>E. coli</italic> tested were phenotypically resistant to at least one of the 14 antimicrobial agents tested. The most common AMR phenotypes were against beta-lactam antibiotics, ampicillin (99.1%; <italic>n</italic> = 231 isolates), and ceftriaxone (98.7%, <italic>n</italic> = 231). Most ESBL-<italic>E. coli</italic> isolates (94.4%) were MDR (resistance to ≥3 antimicrobial classes), of which 42.6% showed co-resistance to at least six classes of antimicrobials. ESBL-<italic>E. coli</italic> isolates with concurrent resistance to ceftriaxone, ampicillin, streptomycin, tetracycline, sulfisoxazole, and chloramphenicol are widespread and detected in all the farms. The detection of MDR ESBL-<italic>E. coli</italic> suggests that dairy cattle can be a reservoir for these bacteria, highlighting the associated public health risk.</p></sec>