[Interaction between biofilm formed by Pseudomonas aeruginosa and antibacterial agents]

We hypothesized that bacterial biofilm formation could be an important factor that make some infection intractable. Interaction of P. aeruginosa biofilm with antibactial agents was examined in vitro.

P. aeruginosa incubated for 6 days in a saline-teflon system formed biofilm on the surfaces of the teflon piece. The biofilm were characteried by dense colonization of bacteria and thick membranous structure that covered the colonies, it was observed with a scanning electron microscopy. CPFX, CAM, ROX and Herba Andrographitis were added to the biofilm bacteria.

The rate of survial of the floating bacteria decreased to 0.02% after 4 hours of contact with 2MIC of Ciprofloxacin (CPFX), but that of biofilms was 41% When 10 micrograms/mL of Clarithromycin (CAM per mL was combined with CPFX, the survial rate for the biofilm bacteria decreased to 0.2%. When 12 micrograms/mL of Roxithromycin (ROX) was combined with CPFX, the survial rate for the biofilm bacteria decreased to 0.5%. When 0.05 g of Burm. f. per mL was combined with CPFX the survial rate for the biofilm bacteria decreased to 2.7%.

We conclude that biofilm bacteria are much more resistant to CPFX than the floating bacteria. The combination of CPFX and CAM, ROX HA were more effective in decreasing the biofilm bacteria survial rate than CPFX alone. The results suggest that the combination of CPFX and CAM, ROX, HA can be one of the therapeutic manauvers against biofilm bacteria.