Epidemiology and Antimicrobial Resistance of Klebsiella pneumoniae at a Tertiary Oncology Centre in Astana, Kazakhstan, 2022-2026: A Prospective Longitudinal Surveillance Study

Background. Klebsiella pneumoniae is a World Health Organization (WHO) critical priority pathogen, and carbapenem-resistant K. pneumoniae (CRKP) causes 50,000-100,000 attributable deaths annually worldwide. Systematic antimicrobial resistance (AMR) data from Central Asia are virtually absent from the global literature. Methods. Longitudinal surveillance study of routine microbiological data from the National Research Oncology Centre (NROC), Astana, Kazakhstan (January 2022-March 2026). Four data sources were integrated: monthly microbial landscape reports (October 2022-September 2024; n=596 K. pneumoniae isolates), a full-year patient-level clinical register (2025; n=91 isolates), monthly landscape reports for first quarter 2026 (Q1 2026 n=50 isolates), and biannual antibiograms (2022, 2026). Isolates were classified as CRKP (4MRGN), 3MRGN, ESBL-producing, or susceptible. Results. A total of 737 K. pneumoniae isolates were identified across the full study period. CRKP (4MRGN) was the dominant phenotype throughout, peaking at 76.4% in January-September 2024 and remaining at 62.0% in Q1 2026. The aggregate MDR rate (CRKP + 3MRGN + ESBL) was 76-87% across all periods, consistently 2-3 times above the global pooled mean of 28.7%. The highest resistance burden was observed in the bone marrow transplantation department (86-98% MDR) and intensive care units (67-100% MDR). Between 2022 and 2026, a profound shift in reserve antibiotic susceptibility was documented: amikacin resistance rose from 8.5% (2022) to 38.1% (Q1 2026, whole institution) and 60% (Q1 2026, intensive care sector), nearly eliminating the sole previously active antibiotic class. In contrast, polymyxins (colistin R 0%, polymyxin B R 2%) and tigecycline (R 52%) emerged as the only agents with retained activity in 2026. Carbapenem resistance showed a modest partial improvement (meropenem R 72%-85%) but remained critically high. Simultaneously, Escherichia coli (ESBL+/MDR) emerged as the dominant pathogen in haematological and surgical departments by 2025-2026, reflecting a broader Enterobacterales resistance crisis beyond K. pneumoniae alone. Conclusions. This study provides the first systematic published AMR surveillance evidence from Kazakhstan over a four-year period. CRKP dominates the institutional microbiological landscape, and the progressive loss of aminoglycoside activity now leaves polymyxins and tigecycline as the last remaining active agents-a development with profound implications for patient safety. These findings represent a critical call to action for antimicrobial stewardship implementation, carbapenemase genotyping, and integration into national and global AMR surveillance systems in Central Asia. Keywords: Klebsiella pneumoniae; CRKP; carbapenem resistance; amikacin resistance; polymyxin; antimicrobial resistance; Kazakhstan; Central Asia; AMR surveillance; oncology