Coexistence of Virulence Factors and Efflux Pump Genes in Clinical Isolates of Pseudomonas aeruginosa: Analysis of Biofilm-Forming Strains from Iran

Background Biofilm formation and efflux pumps (EPs) correlation play a critical role in the pathogenicity and antibiotic resistance of Pseudomonas aeruginosa . In this study, biofilm formation and EP's collaborative role in clinical isolates of P. aeruginosa infection were investigated.Methods Eighty-six (86) P. aeruginosa isolates were collected from different clinical specimens and were confirmed using different biochemical tests. The formation of biofilm was investigated by using a crystal violet assay. Also, EP genes were identified by the PCR method.Results Based on the results, gentamicin-resistant ( n  = 50, 66.29%) and ciprofloxacin-resistant ( n  = 61, 69.66%) strains were the most frequent and colistin ( n  = 1, 1.12%) and ceftazidime ( n  = 12, 7.86%) resistant strains were the least prevalent. Furthermore, 22 isolates (31.42%) were MDR, and 11 isolates (12.35%) were XDR strains. Also, 19 isolates (22.47%) were classified as strong biofilm, 29 isolates (21.34%) as moderate biofilm, and 3 (11.23%) isolates as weak biofilm producers. The distribution of the EP genes was as follows: mexA ( n  = 44, 34.83%), mexB ( n  = 33, 32.58%), oprM ( n  = 59, 29.21%), oprD ( n  = 61, 30.33%), tetA ( n  = 22, 25.58%), tetR ( n  = 19, 22.09%), and emrE ( n  = 21, 24.41%). However, there was a strong significant association between biofilm formation and EPs in P. aeruginosa. Conclusions . In this study, we suggested that the presence of a multidrug resistance efflux pump, MexEF-OprN, significantly reduced P. aeruginosa pathogenicity. In contrast, the presence of the MexAB-OprM and MexCD-OprJ pumps did not affect virulence.