coli’s escape route: AcrAB –TolC efflux-associated aminoglycoside resistance in clinical UTI isolates

Background: aminoglycosides remain important therapeutic options, but rising resistance threatens their efficacy. Among urinary tract infections (UTIs) were the most common bacterial infections, and Escherichia coli is their leading reason. The AcrAB-TolC efflux pump overexpression was recognized as multidrug resistance mechanism in the gram negative bacteria (G-ve).Objective: to conclude the profile of resistance of urinary E. coli samples to aminoglycosides with to investigate presence of the genes acrA and acrB of efflux pump in isolates resistance to all tested aminoglycosides. Methods: twenty samples from clinical UTI patients were isolates at medical city hospital in Baghdad from July 2025 to December 2025. E. coli was identified by cultured on Eosin methylene blue (EMB) with MacConkey agar then confirm test via biochemical test (catalase & oxidase). Susceptibility to amikacin (AK), gentamicin (GN) and tobramycin (TOB) were tested via disk diffusion method. Isolates resistant to all three antibiotics were screened for acrA and acrB via PCR technique.Results: of twenty samples, six isolates were selected to PCR test according to their resistance to all three antibiotics were found that two isolates harboring genes separately and only one isolate harboring both resistance genes, when the isolates gave resistance rate 70% (14/20) for amikacin and 80% (16/20) percentage rate for two antibiotic (GN & TOB) separately. Conclusion: the presence of acrA and acrB in five isolates from six isolates screened to triple aminoglycoside- resistant isolates suggests that AcrAB efflux may contribute to resistance in urinary E. coli. Expression studies or efflux inhibitor assays are needed to confirm a causal role.