ABSTRACT

Introduction: Antimicrobial resistance (AMR) in Escherichia coli (E. Coli) poses a mounting threat to public health. The efficacy of ciprofloxacin (a fluoroquinolone), cefuroxime (a cephalosporin), and amikacin (an aminoglycoside) is increasingly undermined by emerging resistance. The study was conducted to evaluate susceptibility patterns and minimum inhibitory concentration (MIC) trends for ciprofloxacin, cefuroxime, and amikacin in E. Coli urinary isolates at a tertiary care centre over a four-month period.

Methods: This retrospective observational study analysed antimicrobial susceptibility testing (AST) reports from the Microbiology Department over the above time period. MIC values were determined via the VITEK® 2 Compact automated system (bioMérieux) and interpreted using Clinical and Laboratory Standards Institute (CLSI) 2024 guidelines. Susceptibility profiles were expressed as percentages. MICs were expressed in proportions. Geometric means of MIC values were calculated monthly to analyse trends over time.

Results: Among 235 urinary E. coli isolates (85% OPD), resistance rates were high for ciprofloxacin (61.4%) and cefuroxime (66.4%), while amikacin remained largely active (92.7% susceptible). MIC distributions showed ciprofloxacin clustered at 4 µg/mL (≈59%), cefuroxime dominated by very high MICs (≈67% ≥64 µg/mL), and amikacin concentrated at low MICs (≈54% at 2 µg/mL).

Conclusion: High resistance to ciprofloxacin and cefuroxime was observed among urinary E. coli isolates, while amikacin retained excellent activity. These findings support guideline-based use of safer first-line agents and emphasise the importance of ongoing surveillance and antimicrobial stewardship. Empirical therapy for uncomplicated UTIs should be guided by local antibiograms. In severe or complicated cases, amikacin may be used if susceptible, with restricted use, renal adjustment, and monitoring for toxicity.