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Updated: Sep 20, 2026

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Published on: January 30, 2020
In vitro activity of cethromycin, a novel antibacterial ketolide, against Chlamydia pneumoniae
Naoyuki Miyashita1, Hiroshi Fukano, Koichiro Yoshida
1Division of Respiratory Diseases, Department of Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama 701-0192, Japan. nao@med.kawasaki-m.ac.jp
Objectives:
To investigate the in vitro activity of cethromycin, a new ketolide, against Chlamydia pneumoniae.
Methods:
The in vitro activity of cethromycin against 20 isolates of C. pneumoniae was compared with the activities of telithromycin, erythromycin A, azithromycin and clarithromycin against those isolates.
Results:
The MIC at which 90% of the isolates were inhibited and the minimal chlamydiacidal concentration at which 90% of the isolates were killed by cethromycin were both 0.016 mg/L (range 0.016-0.031 mg/L). Cethromycin was the most active antibiotic tested in this study.
Conclusions:
Our results appear to indicate that cethromycin is an effective antibiotic that should play some role in the treatment of respiratory tract infections caused by C. pneumoniae.
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