Raziyeh Ramazani - Department of Microbiology, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran
Rabeeh Izadi Amoli - Department of Microbiology, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran
Mojtaba Taghizadeh Armaki - Infectious Disease and Tropical Medicine Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
Abazar Pournajaf - Infectious Disease and Tropical Medicine Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
Hami Kaboosi - Department of Microbiology, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran

Background and Aim: Carbapenem resistant- Pseudomonas aeruginosa (CRPA) is one of the most important causes of severe and persistent infections. The contributions of different resistance mechanisms to Carbapenems and biofilm formation among a collection of imipenem susceptible and non-susceptible P. aeruginosa isolates were investigated. Materials and Methods: In this cross-sectional study, a total of ۱۱۷ P. aeruginosa isolates were collected. The disc diffusion method assessed the susceptibility of isolates to various antimicrobials. The Carbazole method was used for the detection of alginate producers. Multiplex-PCRs were performed for the detection of biofilm and resistance genes. The expression mRNA levels of efflux pumps were assessed by phenotypic and genotypic (Quantitative Real-time PCR) approaches. Results: The highest resistance rate was related to ceftazidime, chloramphenicol, ceftriaxone, tetracycline, and levofloxacin. MDR phenotype was observed in ۸.۴% of strains. The frequency of carbapenem resistance was also ۲۴.۷%. The Carbazole test was positive at ۵۳.۸%. In general, ۶۲.۴% of isolates were able to form a biofilm, ۲۸.۸% of which were resistant to carbapenem. The distribution of algD and algU genes were ۴۱.۸% and ۲۶.۵%, respectively. The frequency of MBL-encoded genes was as follows; blaIMP (۶۲.۱%), blaVIM (۳۱.۰%), and blaNDM (۶.۸%). The relative levels of MexX, MexC, MexB and MexA mRNA in CRPA strains with active efflux pump were ۸۱.۸%, ۶۳.۶%, ۵۴.۵%, and ۳۶.۴%, respectively. Conclusion: The existence of different resistant mechanisms in P. aeruginosa can cause cross antibiotic resistance, lead to the appearance of resistant strains, and make the treatment difficult. Biofilm production is directly related to antibiotic resistance. Efflux pumps are actively expressed in carbapenem-resistant strains.

Carbapenem, efflux pumps, biofilm, Pseudomonas aeruginosa, کارباپنم, افلاکس پمپ ها, بیوفیلم, سودوموناس آئروژینوزا