Epidemiology and Molecular Mechanisms of Carbapenem Resistance in Klebsiella pneumoniae Isolated from Patients in Intensive Care Units

Background . Carbapenem-resistant Klebsiella pneumoniae (CRKP) is among the most clinically significant healthcare-associated pathogens. CRKP poses the greatest threat in intensive care units (ICUs), where the combination of severe patient conditions, invasive procedures, and high antimicrobial pressure facilitates colonization, nosocomial transmission, and the development of invasive infections. The aim of the study was to synthesize data on the epidemiology of CRKP in ICUs, mechanisms of carbapenem resistance, clonal and plasmid dissemination, diagnostic approaches, current therapeutic strategies, and infection control measures. Material and Methods . A structured narrative review of publications from 2008 to 2026 was performed using PubMed/MEDLINE, SpringerLink, ScienceDirect, eLIBRARY.ru, CyberLeninka, and Google Scholar. The final analysis included a total of 64 sources containing data on ICU patients, epidemiology, molecular resistance mechanisms, diagnosis, treatment, or prevention of CRKP spread. Results . The prevalence of CRKP varies substantially across regions and is determined by a combination of antimicrobial pressure, nosocomial transmission, and circulation of high-risk clones. The primary resistance mechanisms involve the production of KPC, OXA-48-like, and metallo-β-lactamases, frequently combined with ESBL/AmpC, impaired OmpK35/OmpK36 expression, efflux, and heteroresistance. The most epidemiologically significant clones include CG258/ST258, ST11, ST147, and ST307. CRKP infections are associated with increased mortality, prolonged hospitalization, and higher costs. Treatment selection should be based on carbapenemase type, infection site, susceptibility testing results, and drug availability. Containment of the spread requires a combination of active epidemiological surveillance, timely isolation, molecular typing, and antimicrobial stewardship programs. Conclusion. CRKP represents a heterogeneous group of hospital-acquired pathogens whose clinical management is impossible without distinguishing colonization from infection, as well as without type-specific determination of the resistance mechanism. Priority areas remain the standardization of diagnostics, acquisition of comparative data on MBL and OXA-48 producers, and integration of genomic surveillance with infection control measures.