Environmental antimicrobial resistance in urban pigeons: intestinal Escherichia coli from Arequipa, Peru

ABSTRACT Objectives Urban pigeons (Columba livia) are synanthropic birds that live in close contact with human populations and interact continuously with urban environments, making them potential sentinels of environmental antimicrobial resistance. This study aimed to describe phenotypic antimicrobial resistance profiles and co-resistance patterns of Escherichia coli isolated from pigeon fecal samples in Arequipa, Peru. Methods A descriptive cross-sectional study was conducted in April 2025. Cloacal fecal samples were collected from pigeons at four sites representing different urban contexts. E. coli isolates were recovered and tested for antimicrobial susceptibility using the disk diffusion method. Multidrug resistance (MDR) and extended-spectrum β-lactamase (ESBL) phenotypes were determined using standard phenotypic criteria. Results A total of 47 E. coli isolates were analyzed. Resistance was most frequently observed to tetracyclines (31.91%), followed by quinolones, including nalidixic acid (19.15%), and by amphenicols (17.02%) and macrolides (17.02%). Co-resistance to two or more antimicrobial classes was observed in 27.65% (13/47) of isolates, with recurrent patterns involving tetracyclines, quinolones, sulfonamides, and amphenicols. Overall, 12.77% (6/47) of isolates met criteria for MDR, and 8.51% (4/47) exhibited an ESBL phenotype. Conclusions Phenotypic antimicrobial resistance, including MDR and ESBL-producing E. coli, was detected in intestinal isolates from urban pigeons in Arequipa. These findings support the potential role of synanthropic birds as sentinel species for monitoring environmental antimicrobial resistance in urban settings of low- and middle-income countries.