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ORIGINAL RESEARCH article

Front. Vet. Sci.
Sec. Veterinary Epidemiology and Economics
Volume 11 - 2024 | doi: 10.3389/fvets.2024.1504640
This article is part of the Research Topic Antimicrobial Resistance in Veterinary Medicine: Epidemiology, Economic Impact, and Mitigation Strategies View all articles

Antimicrobial drug use and its association with antimicrobial resistance in fecal commensals from cows on California dairies

Provisionally accepted

The final, formatted version of the article will be published soon.

    The objective of this study was to investigate the risk factors associated with isolation of antimicrobial resistant Escherichia coli, and Enterococcus spp. and Streptococcus spp. (ES) from feces of California (CA) cows distributed across California. A longitudinal study was conducted on ten dairies, and a random sample of cattle (late pregnant heifers and dry cows) stratified by each herd's parity distribution were followed monthly from closeup to 120 days in milk during fall to winter 2018 (winter season) and spring to summer 2019 (summer season). Gastrointestinal commensals were isolated from fecal samples and tested for antimicrobial susceptibility using the broth microdilution method against a selected panel of antimicrobial drugs (AMD). Eight dairies reported use of blanket AMD dry cow therapy at dry-off for all lactating cows, while the remaining two dairies did not use any AMD to treat their cows at dry-off. Clinical mastitis was the most common indication for AMD use on the study dairies. Intramuscular administration of ceftiofur hydrochloride for treatment of lameness and unknown disease during lactation was significantly associated with isolating fecal E. coli resistant to tetracycline. Ceftiofur, tetracycline, or trimethoprim-sulfamethoxazole resistance in fecal E. coli were significantly higher in the winter compared to the summer season. In contrast, tetracycline, florfenicol, tilmicosin, tildipirosin, or tiamulin resistance in fecal gram-positive commensals were significantly higher in the summer compared to the winter season. In conclusion, AMD use practices and regional difference were associated with AMR of E. coli and ES in the feces of dairy cattle.

    Keywords: antimicrobial resistance, Antimicrobial drug use, antibiotics, dairy cows, California, Season, Region, Dose

    Received: 01 Oct 2024; Accepted: 30 Dec 2024.

    Copyright: © 2024 Abdelfattah, Ekong, Okello, Chamchoy, Karle, Black, ElAshmawy, Sheedy, Williams, Lehenbauer, Byrne and Aly. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Sharif Shafik Aly, University of California, Davis, Davis, United States

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