Bacterial biofilm in chronic airway infection.

We hypothesized that bacterial biofilm formation could be an important factor that makes some infections intractable, and conducted the following study to confirm the role of bacterial biofilm in airway infection. We first microscopically examined airway surface in patients with an intractable airway infection and detected bacterial biofilms adhering to the airway surface. Most of the airway biofilm diseases were diffuse panbronchiolitis and bronchiectasia due to Pseudomonas aeruginosa or Klebsiella pneumoniae. In vivo examination revealed that chemotaxis of neutrophils in patients with biofilm bacteria was less than that in patients with floating type bacteria. Interaction of Pseudomonas biofilm with antibacterial agents was examined in vitro. The rate of survival of biofilm bacteria was higher than that of floating bacteria in contact with twice the minimal bactericidal concentration of ciprofloxacin (CPFX) or two to 10 times the minimal inhibitory concentration of cefclidin and meropenem which are highly potent antibacterial agents against P. aeruginosa. Additionally, the effects of clarithromycin (CAM) on biofilm bacteria were studied in order to investigate new therapeutic maneuvers against a bacterial biofilm. Also, the combination of CPFX and CAM was more effective in decreasing the bacterial survival rate than CPFX alone. The results suggest that administration CAM can be one of the therapeutic maneuvers against biofilm bacteria.