Objective: Infections due to carbapenem-resistant Klebsiella pneumoniae has been a serious problem in our country and the world. Carbapenem resistance occurs in several mechanism, where the most common one is the production of carbapenemase enzyme. The aim of this study is to investigate the changes in resistance ratio and resistance mechanism in our hospital between 2012 to 2020.

Methods: Carbapenem resistant strains that has been detected in K. pneumoniae strains isolated from several clinical samples were included in this study. KPC, OXA-48, NDM, IMP and VIM resistance genes were investigated by polymerase chain reaction.

Results: A total of 291 (7.5%) carbapenem-resistant K. pneumoniae isolates were identified between 2012 and 2020. The distribution of the resistant genes of strains was as follows: strains with single genes: OXA-48, NDM- 1, KPC and VIM were 113 (38.8%), 32 (11.0%), 7 (2.4%) and 5 (1.7%), respectively. Strains with multiple genes were identified as follows: OXA-48+NDM was 123 (42.3%), OXA-48+KPC was 2 and one strain of each for OXA- 48+VIM, NDM+KPC, NDM+IMP.

Conclusion: The ratio of carbapenem-resistant K. pneumoniae strains was found to be elevated in our hospital. OXA-48 resistance gene was the most prevalent (38.8%) single gene, followed by NDM resistance genes. In addition, coexistence of OXA-48+NDM (42.3%) genes was the most prevalent resistance mechanism in our hospital. Therefore, continious screening of resistance in KDKp strains, and investigation of resistance mechanisms in local and national studies are highly important in the treatment of infections due to these bacteria and control of resistance.