Basic and clinical studies on azithromycin in respiratory infections

We performed a basic evaluation of azithromycin (AZM), a newly developed oral macrolide antibiotic, and clinically studied its application in the treatment of respiratory infections, with the following results. 1. Antibacterial activity The minimum growth inhibitory concentrations (MICs) of AZM against 284 strains of 14 species isolated from clinical material were measured and compared with those of erythromycin (EM) roxithromycin (RXM) and clarithromycin (CAM), oral macrolides. Based on the MIC₉₀, AZM showed similar activity to those of EM and CAM against Gram-positive bacteria, and showed the strongest activity in these macrolides against Gram-negative bacteria. 2. Clinical efficacy AZM was given to 4 patients with pneumonia, 1 patient with chronic bronchitis and 1 patient with acute bronchitis, orally at 250 or 500mg once a day for 3 days. The clinical response was excellent in 2 cases and good in 4. No adverse reactions or abnormal laboratory findings were observed.