Antimicrobial Resistance Mechanisms of Clinical Isolates of Escherichia coli obtained over 3-year period from 2021 to 2023 in Uganda.

Introduction There is a high prevalence of antibiotic-resistant clinical isolates of Escherichia coli in Uganda but there is limited information on the mechanisms of resistance. Objective Mechanisms of antibiotic-resistant E. coli clinical isolates from the Clinical Microbiology Laboratory, Department of Medical Microbiology of Makerere University were determined. Methods The cross-sectional study from 2021 to 2023 was conducted on archived clinical isolates of E. coli isolates from the most prevalent samples; blood, pus swab, rectal swab, urine, and wound swab. E. coli was re-identified by phenotypic methods; Gram stain microscopy, culture and biochemical tests. Antibiotic susceptibility testing and resistance phenotypes; extended spectrum β-lactamase (ESBL), AmpC and carbapenemase production were determined by Kirby Bauer disk diffusion method. Descriptive statistics were used for the results. Results Of the N= 213 isolates of E. coli tested, n=166 (77.9%) were ESBL positive, n=39 (18.3%) was AmpC positive and 3 (1.4%) were confirmed as carbapenemase producing. Conclusion Therefore, ESBL production is the most common mechanism of antibiotic resistance of E. coli isolates from the Clinical Microbiology Laboratory of Makerere University.