Abstract
Background:
Zoonotic diseases are one of the most critical concerns related to pet birds worldwide, and the most common zoonotic infectious bacteria include Salmonella spp., Chlamydia spp., Mycobacterium spp., Listeria spp., Escherichia coli, Campylobacter spp., and Staphylococcus spp.

Aim:
This study aimed to determine the prevalence and antibiotic resistance of Escherichia coli strains in several pet bird species sold at pet stores in Hanoi, Vietnam.

Methods:
A total of 270 pet bird fecal samples were collected from pet bird markets in Hanoi, Vietnam, from June 2025 to April 2026 and transported to the laboratory for analysis within 24 hrs. The E. coli strains were identified using gram staining, biochemical tests, and polymerase chain reaction (PCR). The antibiotic susceptibility of the E. coli strains was assessed using the disc diffusion method.

Results:
Overall, 57.8% of the pet bird fecal samples were E. coli-positive. The highest rate was found in parrots (63.5%), followed by magpies-robins (62.5%), and the lowest was found in nightingale (48.6%); fecal samples from lovebirds, turtledove, and red-whiskered bulbuls had positive rates ranging from 55.3-58.2% (p = 0.7815). E. coli strains exhibited the highest resistance to ampicillin (72.4%), followed by tetracycline (69.9%). Trimethoprim/sulfamethoxazole, streptomycin, chloramphenicol, nalidixic acid, and doxycycline were resistant at rates of 47.4%, 45.5%, 35.3%, 31.4%, and 25.6%, respectively. Norfloxacin, levofloxacin, kanamycin, gentamicin, amoxicillin/clavulanic acid, and cefotaxime were resisted by the isolates at rates ranging from 3.2% to 15.4%. Notably, all isolated E. coli strains were susceptible to ceftazidime and meropenem. Forty-one antibiotic resistance phenotypes were observed, and 54.5% of the isolates was identified as MDR. Notably, although the ampicillin, streptomycin, chloramphenicol, tetracycline, and trimethoprim/sulfamethoxazole resistance phenotype was found in only five strains, as many as other thirty E. coli strains exhibited this resistance pattern along with resistance to other antibiotics.

Conclusion:
E. coli strains originating from pet birds exhibited resistance to multiple antibiotics, including several MDR strains. This highlights the potential role of pet birds as a reservoir for antibiotic-resistant bacteria, raising significant public and animal health concerns.

Key words: Antibiotic resistance; E. coli; Hanoi; MDR; Pet bird.