Effect of culture conditions on the resistance of Pseudomonas aeruginosa biofilms to disinfecting agents.

The relationship between the environmental conditions of biofilm formation and resistance to disinfectants was studied. Anti-biofilm assays were performed against biofilms grown at 20, 30 and 37°C on stainless steel and polycarbonate, over 24 and 48 h. A rise in growth temperature increased the resistance of 24 h biofilms to disinfectants containing didecyldimethylammonium chloride and decreased it to a disinfectant containing alkyldimethylbenzylammonium chloride. The increase in growth temperature coupled with an incubation time of 24 h promoted increases in both matrix production and the membrane rigidity of sessile cells. An increase in incubation time also increased both matrix production and the membrane rigidity of sessile cells. Such phenomena resulted in an increased resistance to disinfectants of biofilms grown at 20 and 30°C. The resistance of 48 h biofilms to disinfectants decreased with an increase in growth temperature despite the increase in matrix production and the membrane rigidity of sessile cells.