Clinical efficacy of dirithromycin in patients with bacteremic pneumonia

Dirithromycin is a new macrolide antimicrobial drug with a long half-life (44 hours) that reaches high tissue concentrations, thus permitting once-daily oral dosing and shorter courses of therapy. Soon after absorption, dirithromycin enters the tissue so rapidly that serum concentrations are comparatively low. It could be hypothesized that these low serum levels could endanger the outcome in patients with bacteremic pneumonia. We reviewed the database on dirithromycin pneumonia (consisting of 1108 patients randomized to receive dirithromycin or erythromycin in two double-masked trials) to ascertain its efficacy in patients with community-acquired pneumonia and concomitant bacteremia. Fourteen (2.5%) of 555 dirithromycin-treated patients and 10 (1.8%) of 553 erythromycin-treated patients had bacteremia. A favorable clinical response posttherapy was observed in 92.3% and 88.9% of these patients with a response assigned, respectively. Overall, favorable response rates were comparable between the two groups in the bacteremic subsets: patients with pneumococcal bacteremia, patients with nonbacteremic pneumococcal pneumonia, and all patients enrolled with acute pneumonia who had a posttherapy clinical response. In the treatment of patients with mild or moderate community-acquired pneumonia, including those with unsuspected and incidental bacteremia, dirithromycin is an effective macrolide antimicrobial drug.