Genetic Acquisition of NDM Gene Offers Sustainability among Clinical Isolates of Pseudomonas aeruginosa in Clinical Settings

New Delhi metallo β-lactamases are one of the most significant emerging resistance determinants towards carbapenem drugs. Their persistence and adaptability often depends on their genetic environment and linkage. This study reports a unique and novel arrangement of blaNDM-1 gene within clinical isolates of Pseudomonas aeruginosa from a tertiary referral hospital in north India. Three NDM positive clonally unrelated clinical isolates of P. aeruginosa were recovered from hospital patients. Association of integron with blaNDM-1 and presence of gene cassettes were assessed by PCR. Genetic linkage of NDM gene with ISAba125 was determined and in negative cases linkage in upstream region was mapped by inverse PCR. In which only one isolate's NDM gene was linked with ISAba125 for mobility, while other two reveals new genetic arrangement and found to be inserted within DNA directed RNA polymerase gene of the host genome detected by inverse PCR followed by sequencing analysis. In continuation significance of this novel linkage was further analyzed wherein promoter site detected by Softberry BPROM software and activity were assessed by cloning succeeding semi-quantitative RT-PCR indicating the higher expression level of NDM gene. This study concluded out that the unique genetic makeup of NDM gene with DNA-dependent-RNA-polymerase favours adaptability to the host in hospital environment against huge antibiotic pressure.