Efficacy and safety of gemifloxacin in the treatment of community-acquired pneumonia: a randomized, double-blind comparison with trovafloxacin.

Sir, File et al. reported eradication rates for Mycoplasma pneumoniae of 93% for gemifloxacin and 95% for trovafloxacin, although the diagnosis was based on serology, not on identification of the organism by either culture or PCR. Serology gives, at best, a clinical endpoint, and identifies possible exposure to an organism. There are data demonstrating poor correlation between serology and culture with M. pneumoniae infection. Even though the patient may have improved or been cured clinically, the organism may persist in the respiratory tract. The same limitations also apply to diagnosis of Chlamydia pneumoniae infection. Again, File et al. report eradication rates of 100% for both antibiotics, but nowhere is it specified whether these patients were diagnosed by isolation of C. pneumoniae or by serology. Previously published studies of treatment of community-acquired pneumonia due to C. pneumoniae confirmed by culture have reported eradication rates of 80% for levofloxacin and 70% for moxifloxacin. Moxifloxacin and levofloxacin have in vitro activities against C. pneumoniae similar to those of gemifloxacin and trovafloxacin. The patients in these studies were all classified as clinical cures despite persistence of the organism after antibiotic treatment. As many as 40–70% of patients with culture-documented C. pneumoniae infection may remain seronegative by the microimmunofluorescence method, which is not standardized, and significant laboratory-to-laboratory variation in performance may occur.