Carbapenem-resistant Klebsiella pneumoniae from clinical infections: a multifactorial analysis of resistance, virulence, and biofilm potential

Introduction Klebsiella pneumoniae has emerged as a major nosocomial pathogen, with hypermucoviscous and hypervirulent variants contributing to severe clinical outcomes. Understanding the interplay between antimicrobial resistance, virulence determinants, and biofilm formation is essential for effective management. Methods A total of 145 clinical isolates of K. pneumoniae were evaluated for antimicrobial susceptibility, virulence genes, and biofilm-forming capacity. Disk diffusion and minimum inhibitory concentration (MIC) assays were performed to determine resistance patterns. Polymerase chain reaction (PCR) was used to detect carbapenemase and virulence genes, while hypermucoviscosity was assessed through the string test. Biofilm formation was quantified phenotypically. Results Disk diffusion revealed that 73% of isolates were multidrug-resistant. MIC testing showed high resistance to meropenem (71%), colistin (61%), and tigecycline (43%). PCR analysis detected bla NDM and bla OXA-48 in 14% of isolates, including two that co-harbored both genes. Virulence determinants such as iucA (aerobactin) and rmpA were present in 7% of isolates. Hypermucoviscosity was observed in 10% of isolates by the string test; however, only two of these exhibited strong biofilm formation. Overall, 86% of isolates demonstrated biofilm-forming ability. Discussion These findings highlight the convergence of antimicrobial resistance, virulence factors, and biofilm-forming capacity in K. pneumoniae . The coexistence of these traits promotes persistence, increases pathogenic potential, and complicates therapeutic interventions, emphasizing the urgent need for strengthened infection control and alternative treatment strategies.