Effect of 14-membered ring macrolide therapy on chronic respiratory tract infections and polymorphonuclear leukocyte activity.

We studied the efficacy of the long-term administration of 14-membered ring macrolides in treating patients with diffuse panbronchiolitis (DPB) (34 patients) and bronchiectasis (BE) (40 patients). Oral administration of erythromycin (400 or 600 mg), roxithromycin (150 or 300 mg) or clarithromycin (200 or 400 mg) given daily for at least 2 months, was evaluated. The efficacy of erythromycin, roxithromycin, and clarithromycin in DPB was 19/24 (79%), 6/7 (86%), and 2/3 (67%), respectively. Efficacy of these agents in BE exceeded 50%. We determined the effect of these macrolides on the activity of polymophonuclear leukocytes (PMNs) obtained from healthy volunteers. There were no significant differences between the effects of these 14-membered ring macrolides and josamycin, a 16-membered ring macrolide which was previously found to be ineffective in treating DPB. Thus, the effectiveness of the 14-membered ring macrolides in treating DPB appears to depend on mechanism(s) other than alterations in PMN activity.