Microbiological efficacy of ABT-773 (cethromycin) for the treatment of community-acquired pneumonia due to Chlamydia pneumoniae.

Nasopharyngeal specimens for culture of Chlamydia pneumoniae were obtained from patients with community-acquired pneumonia enrolled in a randomized study comparing the novel ketolide antibiotic ABT-773 at a dose of 150 mg once a day to 150 mg twice a day, by mouth for 10 days. C. pneumoniae was eradicated from the nasopharynx of 10 of 10 (100%) microbiologically evaluable patients. MICs and MBCs for 13 isolates of C. pneumoniae from 12 patients obtained before and after therapy were performed against ABT-773. The MIC90 and MBC90 of ABT-773 were 0.015 mg/L.