Carbapenems-resistant Pseudomonas aeruginosa mutants are disseminating around the globe. 90%-100% of P. aeruginosa isolates became Carbapenems-resistant mutants in some countries like Thailand and Brazil respectively. Finding alternative therapeutic options instead of carbapenems is the global duty of researchers and institutions. The OprD gene mutation/s has the main role in carbapenems resistance appearance in P. aeruginosa due to the decrease in the outer membrane permeability for carbapenems. Aim: This study aims to assess the antimicrobial activity of carbapenems (imipenem, and meropenem) against Pseudomonas aeruginosa isolated from hospitalized burn patients in Al-Najaf/Iraq, and the role of OprD gene mutations in the resistance. Methods and materials: 76 samples were collected from hospitalized burn patients suffering from burn wounds infections, and the identity of each cultivated microbe was confirmed by VITEK compact system 2 and further confirmation for P. aeruginosa isolates via performing molecular identification by OprD gene detection, 10/12 carbapenems resistant isolates, 1/12 sensitive, and 1/12 intermediate resistant were submitted to OprD gene sequencing by Sanger method

The Most common mechanism used by P. aeruginosa for carbapenem resistance is the decrease of OM permeability, via accumulating mutations cause loss/reduce in the OprD gene expression. This study was designed to detect and determine the OprD gene mutations in carbapenem-resistant isolates of clinical P. aeruginosa isolated from burn wound infections. A 12/20 isolates were sequenced by Sanger method and the results were compared with wildtype (POA1) OprD gene sequence. The PCR products of 12/20 isolates were labeled as A and B, A for F1 forward primer and B for F2 forward primer, packed and sent to the Macrogen company for sequencing. All carbapenem-resistant isolates (10/12) contain mutations in their OprD genes, most of mutations are frameshift mutations, 1/12 still carbapenem-sensitive despite containing 40 mutations. All resistant sequenced isolates contain OprD mutations this might be the main cause and most related to carbapenem-resistance trait in the mutant strains, also despite the OprD mutations in isolate 21A it still carbapenem-sensitive indicates that the OprD mutation isn’t definitive factor for carbapenems resistance trait.