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Journal article
Epidemiology of antimicrobial resistance in commensal E. coli from healthy dairy cattle on a Mediterranean pasture-based system of Australia: A cross-sectional study
Journal of dairy science, Vol.108(1), pp.803-820
2024
PMID: 39369890
Abstract
This study aimed to determine the prevalence of antimicrobial resistance (AMR) in commensal E. coli from healthy lactating cows and calves in the Mediterranean pasture-based feeding dairy system of Western Australia (WA). Fecal samples were collected from healthy adult lactating cows and healthy calves from dairy farms in WA. Presumptive commensal E. coli was isolated from these samples and confirmed using matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Broth microdilution was used to assess the prevalence and the phenotypic AMR profiles of the E. coli isolates to 8 antimicrobial agents of dairy industry and human importance. The minimum inhibitory concentration (MIC) for each isolate was interpreted using the Epidemiologic Cutoff (ECOFF) and Clinical and Laboratory Standards Institute (CLSI) breakpoints. Genomic characterization provided multi-locus sequence types and AMR genes for a selection of isolates categorised as non-wild type (NWT) by ECOFF values for the combination of ampicillin, trimethoprim-sulfamethoxazole, and tetracycline. From a total of 1,117 fecal samples (633 adult, 484 calf) collected across 26 randomly selected farms, 891 commensal E. coli isolates were recovered (541 adult, 350 calf). Commensal E. coli classified as NWT was highest for ampicillin for both adult (68.8%; 95% CI = 64.7 – 72.7) and calf feces (67.1%; 95% CI = 62.0 – 72.0). A large proportion of tetracycline NWT and trimethoprim-sulfamethoxazole NWT organisms were also identified from calf feces, being 44.0% (95% CI = 38.7 – 49.4) and 24.6% (95% CI = 20.2 – 29.4) respectively. Clinical resistance prevalence was low, being higher for calves than for adult feces (ampicillin (adult: 7.8% (95% CI = 5.7 – 10.3); calf: 30.0% (95% CI = 25.2 – 35.1), tetracycline (adult: 6.3% (95% CI = 4.4 – 8.7); calf: 40.3% (95% CI = 35.1 – 45.6), and trimethoprim-sulfamethoxazole (adult: 2.6% (95% CI = 1.4 – 4.3); calf: 22.0% (95% CI = 17.7 – 26.7)). Commensal E. coli originating from calf feces was significantly higher in NWT prevalence compared with adult feces for ciprofloxacin (P = 0.023), gentamicin (P = 0.02), tetracycline (P < 0.001), and trimethoprim-sulfamethoxazole (P < 0.001). The overall number of antimicrobials an isolate was classified as NWT toward varied among farms and was significantly higher for isolates originating from calf than adult feces (P < 0.001). The strain type and sampling source of the commensal E. coli investigated were both associated with the commonality of the resultant resistance genome. Clinical resistance and NWT classification were highest for ampicillin, tetracycline, and trimethoprim-sulfamethoxazole, all antimicrobials commonly used in the treatment of dairy cattle in Australia. Though highly variable across farms, commensal E. coli isolated from healthy dairy calf feces had significantly higher NWT and multidrug resistance (MDR) prevalence compared with feces from healthy adult lactating dairy cows. The resistant genome identified in MDR isolates, though not always consistent with the phenotype, included QnrS1 and genes encoding AmpC β-lactamase and aminoglycoside phosphotransferase.
Details
- Title
- Epidemiology of antimicrobial resistance in commensal E. coli from healthy dairy cattle on a Mediterranean pasture-based system of Australia: A cross-sectional study
- Authors/Creators
- M. Tree - Murdoch UniversityT.J.G.M. Lam - Utrecht UniversityS. McDougall - Statistics New ZealandD.S. Beggs - The University of MelbourneIan D Robertson - Murdoch UniversityAnne L Barnes - Murdoch UniversityAbha Chopra - Murdoch UniversityR. Ram - Institute for Immunology and Infectious Diseases, 390, Discovery Way, Murdoch University 6150, Western Australia, AustraliaC.A. Stockman - Murdoch UniversityTayler Catherine Kent - Murdoch UniversityJoshua W Aleri - Murdoch University
- Publication Details
- Journal of dairy science, Vol.108(1), pp.803-820
- Publisher
- Elsevier Inc.
- Identifiers
- 991005707149307891
- Copyright
- © 2024 The Authors.
- Murdoch Affiliation
- Centre for Animal Production and Health; Centre for Biosecurity and One Health; Centre for Molecular Medicine and Innovative Therapeutics; School of Medical, Molecular and Forensic Sciences; School of Veterinary Medicine
- Language
- English
- Resource Type
- Journal article
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