Determination of virulance factors and quorum sensing genes of Pseudomonas aeruginosa isolates from intensive care unit patients and investigation of the effect of baiucalin on biofilm

Objective: To determine the biofilm formation of P. aeruginosa (n:136) isolates isolated from different samples of intensive care patients, to evaluate their phylogenetic affinities and to investigate the presence of toxA, algD, plcN, plcH, lasB, lasI, lasR, rhII, rhIR which have a regulatory role in the production of virulence factors. In addition, to determine the synergistic efficacy of ceftazidime, colistin combination and the inhibitory effect of baicalin on biofilm formation in strong biofilm producing bacteria (3+). Materials and Methods: Biofilm grading was performed based on absorbance measurement in microplate, which is one of the phenotypic methods for determining biofilm formation. Phylogenetic relationship was investigated by RAPD-PZR method using ERIC-2 primers. The presence of gene regions was determined by polymerase chain reaction (PCR). The in vitro synergistic efficacy of colistin and ceftazidime combination on strains with 3+ biofilm test results was evaluated by checkerboard method. In addition, the anti-biofilm effect of baicalin was determined by sub-MIC. Results: According to the biofilm microplate method, the rates of grading (0,1,2,3) were 37.5%, 44.85%, 12.5%, 5.15%, respectively. According to the microplate method, the baicalin sub-MIC value of the strains with strong (3+) biofilm production was determined to be 512 µg/ml. No synergy was observed in the combination of ceftazidime and colistin. Gene positivity rates (toxA, plcH, algD, lasB, plcN; intact and internal quorum sensing (lasI, lasR, rhlI and rhlR)) were 87.50%, 99.26%, 100%, 100%, 100%, 100%, 93.38%, 83.08%, 98.52%, 93.38%; 95.58%, 97.05%, 100%, 98.52%, respectively. RAPD-PZR was performed to determine their phylogenetic affinities and dendograms were drawn; it was determined that the strains 10-113, 109-39, 50-53, 35-78, 40-74, 45-95-97, 103-49, 133-66, 23-34, 14-28, 1-19, 22-6, 83-86, 105-32, 125-30, 108-82, 117-88 may have the same origin. Conclusion: Biofilm production, virulence gene positivity and multiple antibiotic resistance rates of P. aeruginosa strains isolated from intensive care unit were found to be high, but phylogenetic similarities were determined at 80% threshold. No synergistic effect of ceftazidime, colistin antibiotics was observed in high biofilm producing strains, and it was determined that certain concentration of baicalin was effective on biofilm.