the study of mutation in lasr and pqsr genes in extremely drug resistant and multidrug resistant strains of pseudomonas aeruginosafrom burnwound infection

Background: pseudomonas aeruginosa is among the top 10 resistant bacteria worldwide. its extraordinary resistance is principally due to the function of quorum sensing genes, such as lasr and pqsr, which are mainly involved in antibiotic resistance. objectives: this study aimed to examine possible mutations in lasr and pqsr in resistant clinical isolates of p. aeruginosa. methods: we obtained 120 suspected isolates of p. aeruginosa from burn patients. the isolates were identified by biochemical tests and toxa gene analysis. the pcr products of lasr and pqsr genes were analyzed in seven resistant isolates. then, the sequences were compared with a reference strain. results: we verified ninety-six isolates as absolute p. aeruginosa. according to antibiograms, 95.8% of the isolates were considered as multidrug-resistant, of which 87.5% were extensively drug-resistant. based on dna and protein sequences, only one missense mutation was observed, including r180q in lasr and a314v in pqsr. while r180q decreased the stability of lasr and had a deleterious impact on protein function, a314v had a neutral impact on the protein and increased pqsr protein stability. also, two nonsense mutations in position e259 were observed in the pqsr protein. conclusions: the lasr and pqsr genes possibly can play a key role in antibiotic resistance, but they are not the only factors. hence, studying mutations helps design a promising antibiotic to overcome antibiotic resistance as much as possible.