Five-Year Trends in Antimicrobial Resistance and Carbapenem Resistance Among Klebsiella pneumoniae Isolates in Saudi Arabia

Background: Klebsiella pneumoniae is a leading cause of multidrug-resistant Gram-negative infections worldwide, with carbapenem resistance posing a major therapeutic challenge. Continuous surveillance of antimicrobial resistance is essential to guide empirical therapy, optimize antimicrobial stewardship, and inform infection prevention strategies. Methods: We conducted a retrospective study of 2014 calendar-year patient-level non-duplicate K. pneumoniae isolates collected between 2020 and 2024 at a tertiary care hospital in Riyadh, Saudi Arabia. Only the first isolate of each species per patient per calendar year was included, regardless of specimen source or susceptibility profile. Antimicrobial susceptibility was assessed against 12 antibiotics. Temporal resistance trends were evaluated, and multivariable logistic regression assessed the association between patient setting and resistance, adjusting for study year and specimen source. Results: A total of 415 isolates (20.6%) exhibited an extended-spectrum beta-lactamase (ESBL) phenotype and 55 isolates (2.7%) met the study definition of CRKP. Co-trimoxazole showed a significant decreasing temporal trend after Benjamini–Hochberg correction. Imipenem and meropenem resistance increased from 2.3% in 2020 to 5.3% in 2024; their raw trend p-values were significant, but neither remained significant after multiple-testing correction (BH-adjusted p = 0.055). Inpatient isolates had higher adjusted odds of resistance for all 12 antibiotics. Conclusions: Resistance to several beta-lactams and fluoroquinolones remained substantial. The higher carbapenem resistance observed in 2024 warrants continued surveillance, while interpretation of temporal changes should account for multiple-testing correction and breakpoint revisions during the study period.