Comparative epidemiology of multidrug-resistant Escherichia coli ST131 across human, poultry, and companion animal hosts in Iran
- 1Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
Abstract
Background: Escherichia coli ST131 is a globally prevalent multidrug-resistant pathogen, mainly linked to human infections but increasingly found in animals. Its spread is largely driven by the O25b-ST131 sublineage carrying the CTX-M-15 ESBL. However, limited data exist on its prevalence, transmission, resistance, and genetics in Iran.
Methods: A total of 360 E. coli isolates from human urinary tract infections (UTIs), poultry colibacillosis, and fecal samples from companion animals were collected (2021–2024). Molecular typing identified ST131 clones and determined phylogenetic groups. Antimicrobial agent susceptibility was tested using the CLSI disk diffusion method. Key resistance genes (e.g., blaCTX−M, blaOXA, aac(6’)-Ib-cr) and plasmid replicon types were investigated.
Results: Among 360 isolates, 21 (5.8%) were identified as ST131, with significantly higher prevalence in human UTIs 19/120 (15.8%) compared to poultry 1/120 (0.83%) and companion animal 1/120 (0.83%) sources (p < 0.001). Among ST131 isolates, 94.7% (18/19) from human sources belonged to the O25b clonal group, while 5.3% (1/19) were O16. Both animal-derived ST131 isolates 2/2 (100%) were O25b clonal group. All ST131 isolates 21/21 (100%) belonged to phylogroup B2 and demonstrated multidrug resistance. High resistance rates were observed against ciprofloxacin 18/21 (85.7%), cefotaxime 20/21 (95.2%), and ampicillin 21/21 (100%). ESBL genes were detected in 61.9% of ST131 isolates, and blaCTX−M−15 was identified in 47.4% of urinary strains. Half of the UTI isolates 9/19 (47.4) harbored blaCTX−M−15, blaOXA, and aac(6’)-Ib-cr simultaneously. IncFIA (78.9%) and IncFIB (73.6%) plasmids were predominant in human isolates, while HI2 replicon was more common in non-human sources 2/2 (100%), including one dog sample and one poultry sample.
Conclusions: ST131 poses a significant public health concern in Iran, particularly in human UTIs, due to its multidrug resistance and ESBL production. The predominance of O25b clonal group and differential resistance patterns between human and animal sources suggest distinct evolutionary pressures. Importantly, this study provides the first report of ST131 in poultry and companion animals in Iran (representing a critical surveillance gap previously undocumented in the Iranian veterinary literature), thereby establishing a foundational baseline for future comparative genomic studies to elucidate interspecies transmission dynamics and resistance evolution.
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BibTeX
@article{hafiz2026comparative,
title = {{Comparative epidemiology of multidrug-resistant Escherichia coli ST131 across human, poultry, and companion animal hosts in Iran}},
author = {Maryam Hafiz and Mahdi Askari Badouei and Gholamreza Hashemi Tabar and Ali Nemati},
journal = {BMC Veterinary Research},
year = {2026},
month = aug,
doi = {10.1186/s12917-026-05758-4},
url = {https://doi.org/10.1186/s12917-026-05758-4},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Comparative epidemiology of multidrug-resistant Escherichia coli ST131 across human, poultry, and companion animal hosts in Iran
AU - Maryam Hafiz
AU - Mahdi Askari Badouei
AU - Gholamreza Hashemi Tabar
AU - Ali Nemati
PY - 2026
DA - 2026/08/08
JO - BMC Veterinary Research
DO - 10.1186/s12917-026-05758-4
UR - https://doi.org/10.1186/s12917-026-05758-4
AB - Background: Escherichia coli ST131 is a globally prevalent multidrug-resistant pathogen, mainly linked to human infections but increasingly found in animals. Its spread is largely driven by the O25b-ST131 sublineage carrying the CTX-M-15 ESBL. However, limited data exist on its prevalence, transmission, resistance, and genetics in Iran. Methods: A total of 360 E. coli isolates from human urinary tract infections (UTIs), poultry colibacillosis, and fecal samples from companion animals were collected (2021–2024). Molecular typing identified ST131 clones and determined phylogenetic groups. Antimicrobial agent susceptibility was tested using the CLSI disk diffusion method. Key resistance genes (e.g., blaCTX−M, blaOXA, aac(6’)-Ib-cr) and plasmid replicon types were investigated. Results: Among 360 isolates, 21 (5.8%) were identified as ST131, with significantly higher prevalence in human UTIs 19/120 (15.8%) compared to poultry 1/120 (0.83%) and companion animal 1/120 (0.83%) sources (p < 0.001). Among ST131 isolates, 94.7% (18/19) from human sources belonged to the O25b clonal group, while 5.3% (1/19) were O16. Both animal-derived ST131 isolates 2/2 (100%) were O25b clonal group. All ST131 isolates 21/21 (100%) belonged to phylogroup B2 and demonstrated multidrug resistance. High resistance rates were observed against ciprofloxacin 18/21 (85.7%), cefotaxime 20/21 (95.2%), and ampicillin 21/21 (100%). ESBL genes were detected in 61.9% of ST131 isolates, and blaCTX−M−15 was identified in 47.4% of urinary strains. Half of the UTI isolates 9/19 (47.4) harbored blaCTX−M−15, blaOXA, and aac(6’)-Ib-cr simultaneously. IncFIA (78.9%) and IncFIB (73.6%) plasmids were predominant in human isolates, while HI2 replicon was more common in non-human sources 2/2 (100%), including one dog sample and one poultry sample. Conclusions: ST131 poses a significant public health concern in Iran, particularly in human UTIs, due to its multidrug resistance and ESBL production. The predominance of O25b clonal group and differential resistance patterns between human and animal sources suggest distinct evolutionary pressures. Importantly, this study provides the first report of ST131 in poultry and companion animals in Iran (representing a critical surveillance gap previously undocumented in the Iranian veterinary literature), thereby establishing a foundational baseline for future comparative genomic studies to elucidate interspecies transmission dynamics and resistance evolution.
SN - 1746-6148
ER -