Efficacy of azithromycin compared with spiramycin in the treatment of odontogenic infections.

Sixty patients with acute odontogenic infections were randomly allocated to oral treatment with azithromycin 500 mg/day once-daily for three days (n = 30) or spiramycin 3,000,000 units three-times daily for seven days (n = 30). Baseline and post-treatment oral specimens were collected from patients to test for pathogenic bacteria. Aerobic bacteria were tested using the Kirby-Bauer disc diffusion method, and anaerobic bacteria with a broth microdilution method, for their susceptibility to azithromycin and spiramycin. A greater incidence of resistance was found in the spiramycin group than in the azithromycin group. The bacteriological assessment showed that the normal balance of microflora was re-established in 67% of patients treated with azithromycin vs 53% in the group treated with spiramycin. Clinical cure was higher in the azithromycin treatment group (97%) compared with the spiramycin group (73%). These results indicate that three-day azithromycin, possibly because of its unusual pharmacokinetics, is more effective than seven-day spiramycin in the treatment of odontogenic infections.