Evaluation of carbapenem-resistant genes and colistin susceptibility in gram negative organisms from clinically significant samples

Introduction: The rapid global spread of carbapenem-resistance in microorganisms is a threat to the health system. This study aims to evaluate carbapenem resistance in different bacterial isolates like E coli, Klebsiella pneumoniae, Acinetobacter and Pseudomonas species and detection of genes conferring the carbapenem resistance in bacteria using Multiplex PCR. Materials and Method: A total of 101 clinically significant samples from the various patients such as blood, urine, pus, sputum, aspirates, and tissue were collected. Antibiotic susceptibility testing done by standard Kirby Bauer disc diffusion & Vitek 2 system. MIC values of Colistin for all the isolates was determined by Broth Microdilution method. Detection of carbapenemase genes was done by using Multiplex PCR. Results: The most prevalent Carbapenem resistant organism was Klebsiella species(53%). NDM gene was the highest of all the other carbapenemase encoding genes detected constituting up to 68%. Out of these 15, 12 Klebsiella pneumoniae, 2 Acinetobacter species, and 1 Escherichia coli harbored the NDM gene. The prevalence of OXA-48, VIM and IMP genes were about 9%. There were 2 IMP and 2 OXA-48 genes each was found in Escherichia coli and Klebsiella species. The carbapenem resistance encoding gene KPC was found only in the single isolate of Acinetobacter isolated from blood culture. The organisms showed higher resistance to Colistin(56%). Conclusion: Evaluation of bacterial resistance to carbapenems contributes to know the appropriate treatment available, and the reduction of morbidity, mortality and dissemination of resistance. Detection of the genes conferring Carbapenem resistance helps in the study of resistant mechanism.