Comparative Analysis of Antimicrobial Resistance in Escherichia coli Isolated from Household and Ornamental Pigeons in Isfahan, Iran: A One Health Perspective

Introduction: Antimicrobial resistance (AMR) is a major global health threat. Household pigeons, due to their close contact with human habitats and waste, can act as reservoirs for resistant E. coli strains, while ornamental pigeons are kept as pets in controlled environments. No study in Iran has directly compared AMR patterns between these two pigeon populations. This study aimed to compare the AMR profiles of E. coli isolated from household and ornamental pigeons in Isfahan, Iran.

Methods: In this cross-sectional comparative study, 150 fresh fecal samples were collected (80 from household pigeons in urban areas, 70 from ornamental pigeons in breeding centers) from October 2025 to February 2026. E. coli was isolated using MacConkey and EMB agar and confirmed by IMViC tests. Antimicrobial susceptibility was tested using the Kirby-Bauer disk diffusion method for 12 antibiotics according to CLSI M100 2024 guidelines. MDR was defined as resistance to ≥3 antibiotic classes. Data were analyzed using Fisher's exact test (p < 0.05).

Results: E. coli was isolated from 68 of 80 household pigeons (85%) and 12 of 70 ornamental pigeons (17.1%) (p < 0.001). Household isolates showed significantly higher resistance to ampicillin (73.5% vs. 25%, p = 0.002), tetracycline (86.8% vs. 33.3%, p < 0.001), and trimethoprim-sulfamethoxazole (82.4% vs. 16.7%, p < 0.001). Notably, all isolates were completely susceptible to ciprofloxacin. MDR prevalence was significantly higher in household pigeons (47.1%) compared to ornamental pigeons (8.3%) (p = 0.014; OR = 9.8).

Conclusions: Household pigeons harbor significantly higher rates of E. coli and MDR strains compared to ornamental pigeons. This highlights the potential role of urban pigeons as overlooked reservoirs of AMR bacteria within the One Health framework. Enhanced surveillance of urban wildlife for AMR is urgently needed.