In the investigation of the disease manifestation of DPB from the viewpoint of biofilm disease, the important factors are an excess antigen-antibody reaction in which alginate acts as the antigen and the resulting formation of immune complex. The effects of 14- and 15-membered macrolides are inhibition of immunoreaction induced by alginate and their inhibitory effect on alginate production serving as an antigen at the GMD level. Further, the specificity of macrolides on these actions was also evidenced from the standpoint of structural activity. In my opinion, based on the similarity in pathogenic process between patients with infected cystic fibrosis and patients with Pseudomonas biofilm disease, long-term administration of 14- or 15-membered ring macrolides can be tried in patients with infected cystic fibrosis.