Change of intrinsic drug resistance in the formation of Pseudomonas aeruginosa biofilms

Objective To screen gyrA mutant and multidrug resistance (MDR) efflux pump (MexAB-OprM) of Pseudomonas aeruginosa (Pa) and to identify the contribution of gyrA mutant and MDR efflux pump to bacterial drug resistance during the formation of Pa biofilms. Methods The strains of gyrA mutant and MDR efflux pump were clinical isolates and detected by PCR. Tri-relative hybridization experiments were performed to transfer report gene of GFP into sensitive Pa strains. The formation of bacterial biofilms was observed by scanning electron microscope followed by analysis of bacterial survival rate. Results The fluorescent strains with pGFPuv could form mature biofilms on Teflon surface. Over a period of 72 h, the survival rate of biofilm bacteria was more than 50% in its′ MBC of ciprofloxacin. Conclusion The express of gyrA mutation and MDR efflux played major roles in Pa resistance during the initial stage of biofilm development. But after 72 h of incubation, there was no significant difference between mutants and sensitive strains in terms of survival rate.