What question did this study set out to answer?

This research investigates the prevalence of antimicrobial resistance in E. coli from dairy cattle and its association with local antimicrobial use practices.

March 10, 2026Open Access

Antimicrobial resistance of Escherichia coli from dairy cattle farms with different antimicrobial use practices in Ethiopia

Key Points

This research investigates the prevalence of antimicrobial resistance in E. coli from dairy cattle and its association with local antimicrobial use practices.
Conducted a cross-sectional study in six Ethiopian districts with varied dairy farming systems.
Selected 83 farms using stratified sampling and collected 1,149 samples from cattle and the environment.
Isolated E. coli using standard methods and tested 310 isolates for antimicrobial susceptibility.
Calculated multidrug resistance and multiple antibiotic resistance index values.
Assessed associations between antimicrobial use, production systems, and AMR using mixed-effects regression models.
Detected ≥ 1 antimicrobial resistance in 89% of E. coli isolates.
High resistance rates were observed for tetracycline (65%), streptomycin (56%), and sulfisoxazole (43%).
46.5% of isolates showed multidrug resistance.
Intensive systems and sulfonamide use were linked to higher quinolone resistance.
MARI values were higher in central districts and correlating with specific antimicrobial uses.

Abstract

• Penstrep use is higher in central Ethiopian dairy farms, while oxytetracycline use is lower in intensive farming systems. • Commensal Escherichia coli show high AMR prevalence in Ethiopian dairy farms. • Resistance is high to commonly used antibiotics, particularly tetracycline and streptomycin. • MARI values significantly associate with geographical location and farm-level antimicrobial use. • Strong link between farm-level antimicrobial use and multiclass resistance, underscoring the need for targeted stewardship. This study investigated antimicrobial resistance (AMR) in commensal Escherichia coli from Ethiopian dairy farms and assessed associations with farm-level antimicrobial use (AMU). A cross-sectional study was conducted in six districts across intensive, semi-intensive, and extensive dairy systems. Eighty-three farms were selected using stratified sampling, and 1,149 cattle and environmental samples (feces, udder milk, bulk tank milk, and udder, bucket and floor swabs) were collected. E. coli was isolated using standard methods, and 310 isolates were tested for susceptibility to nine antimicrobials using Bauer-Kirby disk diffusion method. Multidrug resistance (MDR) and multiple antibiotic resistance index (MARI) were calculated. Associations between AMU, production system, and location with AMR/MARI were assessed using mixed-effects regression models. Oxytetracycline (80%) and penicillin-streptomycin (73%) were the most used antimicrobials. Penstrep use was significantly higher in central districts, while oxytetracycline use was lower in intensive systems. Resistance to ≥ 1 antimicrobial was detected in 89% of isolates, with high rates to tetracycline (65%), streptomycin (56%), and sulfisoxazole (43%). MDR was observed in 46.5% of isolates. Intensive systems and sulfonamide use were statistically associated with higher odds of quinolone resistance, while oxytetracycline use was associated with aminoglycoside resistance. Farms in central Ethiopia had substantially higher odds of resistance to antifolates. MARI values were significantly higher in central districts and on farms using penicillin and sulfonamides. AMR in E. coli is widespread in Ethiopian dairy farms, with AMU strongly associated with MDR. Targeted interventions are urgently needed to mitigate AMR and safeguard public health.

Read Full Paperexternally

اسأل الذكاء الاصطناعي

Bookmark

View Full Paper