ROLE OF QUORUM SENSING GENES IN PSEUDOMONAS AERUGINOSA TO FORM BIOFILM AND THEIR RELATION TO ANTIBIOTIC RESISTANCE

*Anwar Sabah Fadhil and Mohammed Hashim AL-Yasiri

Quorum sensing is the regulation of gene expression in response to fluctuations in cell-population density. Quorum sensing bacteria produce and release chemical signal molecules called autoinducers that increase in concentration as a function of cell density. In this study, thirty isolates of P. aeruginosa were tested for seven types of antibiotics. On the other hand, the ability of P. aeruginosa isolates was tested to form biofilm membranes using crystal violet stain. All P. aeruginosa (13 isolates), which were positive to form biofilm, submitted to molecular study for detecting of two Quorum Sensing genes (llsaI and rrhI genes) related to biofilm formation in P. aeruginosa. Twenty-nine isolates were found to be resistant to one type of antibiotic, and twenty-six isolates were resistant to more than one antibiotic. The highest resistance was reported against CAZ (90%), followed by AK (80%) and CN (70%). However, the highest sensitive was observed in IPM (73.33%), and CIP (56.67%). The results of biofilm formation reported that 13 (43.3%) produce biofilm, while 17 (56.7%) not produce biofilm. Together llsaI and rrhI genes were detected in 10 isolates and only one gene of them was detected in three isolates compare with control isolate that was not biofilm producer and lack to these genes. In conclusion, P. aeruginosa will be developed antibiotic resistance when a specific QS gene is stimulated to form biofilm.