A molecular New Update on the Biofilm Production and Carbapenem Resistance Mechanisms in Clinical Pseudomonas aeruginosa Isolates

 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.

 In this cross-sectional study, a total of 117 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.

The highest resistance rate was related to ceftazidime, chloramphenicol, ceftriaxone, tetracycline, and levofloxacin. MDR phenotype was observed in 8.4% of strains. The frequency of carbapenem resistance was also 24.7%. The Carbazole test was positive at 53.8%. In general, 62.4% of isolates were able to form a biofilm, 28.8% of which were resistant to carbapenem. The distribution of algD and algU genes were 41.8% and 26.5%, respectively. The frequency of MBL-encoded genes was as follows; blaIMP (62.1%), blaVIM (31.0%), and blaNDM (6.8%). The relative levels of MexX, MexC, MexB and MexA mRNA in CRPA strains with active efflux pump were 81.8%, 63.6%, 54.5%, and 36.4%, respectively.

 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.