Chlamydia Research Laboratory, Division of Infectious Diseases, Department of Pediatrics, State University of New York, Downstate Medical Center, Brooklyn, NY 11203-2098, USA
Keywords: fluoroquinolones , C. pneumoniae , community-acquired pneumonia
Sir,
As part of our research into the diagnosis and treatment of infection due to Chlamydia spp., we have had the opportunity to test a number of new compounds against these organisms. Harnett et al.1 recently reported a comparative study of the in vitro activity of a new fluoroquinolone, ABT-492, against a wide range of bacteria, including three strains of Chlamydia trachomatis and one isolate of Chlamydia pneumoniae. We recently tested ABT-492 against 13 recent clinical isolates of C. pneumonia from patients with community-acquired pneumonia enrolled in a multicentre treatment study.
Isolates and comparator antibiotics used in the study are presented in Table 1. Antibiotics were provided by the manufacturers. Antibiotic susceptibility testing was performed in cycloheximide-treated HEp-2 cells grown in 96-well microtitre plates, as previously described.2 MICs and MBCs are summarized in Table 1. The MIC90 and MBC90 of ABT-492 were 0.125 mg/L (range 0.060.125 mg/L) compared with 0.125 mg/L for azithromycin and 0.5 mg/L for levofloxacin. The activity of ABT-492 against C. pneumoniae was similar to those we have previously reported for gatifloxacin, moxifloxacin and gemifloxacin.3 However, these results were four-fold higher than the MIC of 0.03 mg/L Harnett et al.1 reported for the one isolate of C. pneumoniae (TW-183) tested in their study. Harnett et al. used McCoy cells, which are 10100-fold less susceptible to C. pneumoniae than the HEp-2 cells used in the present study, which may lead to lower endpoints.
|
Footnotes
* Corresponding author. Tel: +1-718-270-3097; Fax: +1-718-270-1985; Email: mhammerschlag{at}pol.net
References
1
.
Harnett, S. J., Fraise, A. P., Andrews, J. M. et al. (2004). Comparative study of the in vitro activity of a new fluoroquinolone, ABT-492. Journal of Antimicrobial Chemotherapy 53, 78392.
2
.
Hammerschlag, M. R., Reznik, T., Roblin, P. M. et al. (2003). Microbiological efficacy of ABT-773 (cethromycin) for treatment of community acquired pneumonia due to Chlamydia pneumoniae. Journal of Antimicrobial Chemotherapy 51, 10258.
3
.
Hammerschlag, M. R. (2000). Activity of gemifloxacin and other new quinolones against Chlamydia pneumoniae: a review. Journal of Antimicrobial Chemotherapy 45, Suppl. S1, 359.
4
.
Roblin, P. M. & Hammerschlag, M. R. (1998). In vitro activity of a new ketolide antibiotic, HMR 3647, against Chlamydia pneumoniae. Antimicrobial Agents and Chemotherapy 42, 15156.
|