Genotypic and phenotypic antibiotic resistance in Escherichia coli isolates obtained from intestine of retail rainbow trout (Oncorhynchus mykiss) in Kerman, Iran

BACKGROUND AND OBJECTIVESAntibiotics are employed worldwide to treat diseases of humans and other animals. The uncontrolled use of antibiotics increases the emergence of resistant bacteria and makes it difficult to treat the infections.MATERIALS AND METHODSOne hundred and sixty-six rainbow trout fish were randomly collected from different retail stores in Kerman City, southeast of Iran. Intestine samples were obtained from each fish using a swab. After the isolation and biochemical confirmation process, Escherichia coli (E. coli) isolates were screened for antimicrobial resistance (AMR) and phenotypes.RESULTS AND DISCUSSIONE. coli strains were isolated from ۸.۶۰% of the swabs. Among the isolated strains, the most prevalent resistance genes were dhfrI (۴۰%), followed by blaCTX-M (۲۰%), sul۱ (۲۰%), tetB (۲۰%), sul۲ (۲۰%), and other resistance genes (tetA, dhfrV, qnrA, cat۱, blaTEM, blaSHV, blaOXA) did not exhibit any prevalence. The findings revealed high resistance rates to antibiotics such as erythromycin (۸۰%), ciprofloxacin (۶۰%), amoxicillin (۶۰%), trimethoprim (۶۰%), Oxytetracycline (۶۰%), nitrofurantoin (۶۰%), flumequine (۶۰%), tetracycline (۴۰%), chloramphenicol (۴۰%), florfenicol (۴۰%), trimethoprim-sulphamethoxazole (۲۰%), and cefotaxime (۲۰%). Additionally, ۴۰% of the isolated E. coli strains tested positive for extended-spectrum beta-lactamases (ESBL).CONCLUSIONThese findings indicate that retail rainbow trout can serve as passive carriers of multidrug-resistant E. coli strains, highlighting the importance of adopting proper hygiene practices, managing water quality, and practicing responsible antibiotic use in fish farming to minimize the spread of antibiotic-resistant bacteria.

کلیدواژه ها:

Genotypic ، phenotypic ، Escherichia coli ، rainbow trout ، intestine