LONG-TERM EFFECT OF ERYTHROMYCIN THERAPY IN PATIENTS WITH CHRONIC PSEUDOMONAS-AERUGINOSA INFECTION

Background - Diffuse panbronchiolitis is a chronic infection of the lo wer respiratory tract common among the Japanese people, with a persist ent Pseudomonas aeruginosa infection in the late stage and sustained n eutrophil retention in the airways. The long term effect of erythromyc in was examined retrospectively in a group of patients with diffuse pa nbronchiolitis, with and without P aeruginosa infection, and the relat ionship between drug-induced bacterial clearance and clinical improvem ent was investigated. Methods - The history, daily volume of sputum, t ype of organisms in sputum cultures, pulmonary function tests, arteria l blood gas tensions, and chest radiographs were compared in 16 patien ts with diffuse panbronchiolitis with P aeruginosa infection and 12 wi thout. The total and differential cell counts in the bronchoalveolar l avage (BAL) fluid were compared in 14 of the 28 patients (five of whom were infected with P aeruginosa) before and after 1-12 months of trea tment with erythromycin (600 mg/day). The outcome of treatment in pati ents showing clearance of organisms on repeated sputum cultures was co mpared with that in those demonstrating persistence of bacteria in the sputum and patients with normal flora. Results - Erythromycin improve d respiratory function and arterial blood gas tensions irrespective of the presence or absence of P aeruginosa in the sputum. Treatment also resulted in a reduction in the BAL fluid total cell count and the per centage of neutrophils in both groups of patients. There were no diffe rences between patients in whom the bacteria cleared and those with pe rsistent bacteria or patients with a normal flora with regard to the d egree of improvement of respiratory function, arterial blood gas tensi ons, and BAL fluid cell composition. Conclusion - The results suggest that the efficacy of erythromycin in diffuse panbronchiolitis may be d ue to an anti-inflammatory effect, independent of P aeruginosa infecti on or bacterial clearance.