Emergence of Plasmid Mediated Colistin Resistance Genes in Klebsiella Pneumoniae Clinical Isolates from Najaf Hospitals

Background: The "last resort" medications for treating infections caused by carbapenem-resistant Enterobacteriaceae are polymyxins, such as colistin. Objective: prevalence of plasmid-mediated colistin resistance genes that contribute to colistin resistance in Klebsiella pneumoniae that produce carbapenemase in clinical isolates in Najaf hospitals Subjects and Methods: Cross-section study was conducted between November 2024 to February 2025 at Al-Najaf hospitals. Clinical specimens were gathered from individuals who were either admitted to or visited hospitals, All isolates in the current study had been identified by depending on morphological characteristic, microscopically examination, and biochemical tests. Antibiotics susceptibility was performed by disk diffusion methods. Colistin broth disk elution test for colistin antibiotic. The K. pneumoniae isolates exhibited resistance to colistin were examined for the presences of plasmid mediated mcr-1 to mcr-8 genes. And bla genes (bla CTX-M, blaSHV, blaOXA, and blaIMP) were identified using the PCR technique. Results: A total of 150 isolates were obtained during the study period from the major hospitals in Najaf; 78(52%) were recognized as K. pneumoniae. Antibiotic resistance among isolates diverse from 11.5% for colistin to 100% for ampicillin, amoxicillin and amoxicillin-clavulanic. Genotype bla gene positive ESBL for K. pneumoniae isolates 13 (16.6%) have blaOXA, 13 (16.6%) blaCTX-M isolates have and 17(21.8%) have blaSHV, the frequency of carbapenemase-encoding genes among the isolates, bla IMP was negative for all isolates. All phenotype colistin resistance isolates 9 K. pneumoniae, the frequencies of plasmid mediated colistin resistance mcr genes. No isolates were positive for plasmid encoded colistin resistance gene mcr1, mcr-2, mcr-3, mcr-4, mcr-5, mcr-7, mcr-8, while all the eight-colistin resistant isolates harbored the plasmid mediated colistin resistance gene mcr-6. Conclusion: The proportion of colistin-resistant K. pneumoniae isolates in Al-Najaf hospital is alarming. This is the first report of plasmid encoded colistin resistance K. pneumoniae isolate that carries mcr-6 in Al-Najaf hospital.