Copyright © 1998, American Society for Microbiology In Vitro Activity of a New 8-Methoxyquinolone, BAY 12-8039, against Chlamydia pneumoniae

The in vitro susceptibilities of 10 strains of Chlamydia pneumoniae to a new 8-methoxyquinolone, BAY 12-8039, and to ofloxacin, doxycycline, and erythromycin were determined. The activity of BAY 12-8039 was similar to that of ofloxacin, with a MIC at which 90 % of the isolates had no inclusions and a minimal chlamydicidal concentration at which 90 % of the isolates had no inclusions after passage of 1.0 mg/ml, but this activity was less than those of doxycycline and erythromycin. Chlamydia pneumoniae is a frequent cause of community-acquired respiratory tract infections, including pneumonia and bronchitis, in adults and children (1, 6). Quinolones have at-tracted interest as potential therapies for community-acquired respiratory tract infections because they are active against a wide range of pathogens responsible for these infections, in-cluding Mycoplasma pneumoniae, Streptococcus pneumoniae (both non-penicillin-resistant and penicillin-resistant strains), and C. pneumoniae (2, 4, 12, 17). We previously reported that several quinolones, including ofloxacin, levofloxacin, grepa-floxacin, sparfloxacin, and trovafloxacin, have significant activ-ities against C. pneumoniae in vitro (3, 7, 8, 14, 15). We tested a new 8-methoxyquinolone, BAY 12-8039, for activity against C. pneumoniae in comparison with ofloxacin, doxycycline, and erythromycin