Comparison of antibiotic resistance in Klebsiella pneumoniae isolates from a hospital in Mashhad, Iran: a 35-year retrospective analysis (1989 vs. 2024)

Aims Klebsiella pneumoniae infections are one of the significant causes of mortality, especially among hospitalized patients. The spread of antibiotic resistance patterns such as extended-spectrum β-lactamases (ESBLs), K. pneumoniae carbapenemase (KPC), etc. poses significant challenges to effective treatment. Therefore, monitoring alterations in the prevalence of antibiotic resistance over the years can help prescribe antibiotics optimally. This study investigated and compared the prevalence of antibiotic resistance of K. pneumoniae in the same tertiary care hospital in Mashhad, Iran, in 1989 and 2024.Patients and methods In this study, the antibiotic resistance of 177 and 844 K. pneumoniae strains isolated from patient specimens using the disk diffusion method based on Clinical Laboratory Standards Institute (CLSI) was used in both years (1989 vs 2024). The chi-square test was used for comparisons, with a p-value of less than 0.05 considered significant.Results The comparison of antibiotic resistance in 1989 and 2024 demonstrated that resistance to amikacin, cephalosporin, and trimethoprim-sulfamethoxazole had increased significantly (p < 0.001). In contrast, a decrease in tetracycline resistance has been observed.Conclusions The significant rise in antibiotic resistance underscores the urgent need for enhanced control and prevention strategies.Ethical code IR.MUMS.MEDICAL.REC.1398.141.