Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 18 1 2026 02 14 14 22 Susheem Ramakrishnan Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar, J&K, India Gulnaz Bashir Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar, J&K, India Nargis Bali Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar, J&K, India Sabah Rashid Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar, J&K, India Dona Mathew Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar, J&K, India Qounser Nisar Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar, J&K, India Mohd Mir State-Level VRDL Laboratory, Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar, J&K, India 2025 10 22 2026 01 18 Background and Objectives: Carbapenem resistance mediated by blaNDM-1 in Klebsiella pneumoniae has emerged as a major challenge, particularly in intensive care settings with high antibiotic pressure. This compromises therapeutic options and contributes to poor clinical outcomes. The present study aimed to determine the prevalence of blaNDM-1 among isolates of K. pneumoniae from a tertiary care hospital, evaluate the performance of phenotypic tests against PCR-based detection, assess antimicrobial susceptibility profiles, and analyze clinical outcomes. Materials and Methods: In this study, over 18 months, 130 non-duplicate K. pneumoniae isolates were identified, and antimicrobial susceptibility testing was performed by VITEK-2 Compact and broth microdilution for colistin. Imipenem-resistant isolates were subjected to the Combined disc diffusion test (CDDT) and Double disc synergy test (DDST) for metallo-beta-lactamase (MBL), and conventional PCR targeting blaNDM-1. Demographic data and outcomes were recorded. Results: Of the 130 isolates, 111 were imipenem-resistant, of which CDDT detected MBLs in 94.6%, and DDST detected MBLs in 76.6%. PCR confirmed blaNDM-1 in 77.5% and was more commonly associated with cases of sepsis. blaNDM-1 -positive isolates were resistant to β-lactams, fluoroquinolones and aminoglycosides. No isolate was found to be colistin-resistant. 26.7% of the patients with blaNDM-1 -positive bacteremia died. Conclusion: This study highlights the high prevalence of blaNDM-1 in K. pneumoniae isolates. Among the phenotypic tests, CDDT outperformed DDST and showed the best agreement with PCR, supporting its use as a screening method for MBL, but confirmatory PCR remains essential. The restricted treatment options underscore the need for stringent infection control and robust antimicrobial stewardship to curb transmission and preserve last-line agents. https://ijm.tums.ac.ir/index.php/ijm/article/view/5876 https://ijm.tums.ac.ir/index.php/ijm/article/download/5876/1857