Bacteriostatic and Bactericidal Activities of Tigecycline against Coxiella burnetii and Comparison with Those of Six Other Antibiotics

ABSTRACT The present article is a study of the in vitro susceptibility of eight Greek Coxiella burnetii isolates, derived from patients with acute Q fever, and two reference strains of Coxiella burnetii to tigecycline. The bacteriostatic activity of tigecycline was compared with those of six other antibiotics using a shell vial assay. The MICs of the examined antibiotics were as follows: tigecycline ranged from 0.25 to 0.5 μg/ml; doxycycline, trovafloxacin, and ofloxacin ranged from 1 to 2 μg/ml; linezolid and clarithromycin ranged from 2 to 4 μg/ml; and ciprofloxacin ranged from 4 to 8 μg/ml. Tigecycline was effective in inhibiting the infection of Vero cells by C. burnetii. No bactericidal activity was observed against C. burnetii at 4 μg/ml.

In Vitro Susceptibility of Coxiella burnetii to Linezolid in Comparison with Its Susceptibilities to Quinolones, Doxycycline, and Clarithromycin

ABSTRACT The in vitro susceptibility to linezolid shown by nine Greek isolates of Coxiella burnetii derived from patients with acute Q fever was investigated. MICs of linezolid were compared with those of pefloxacin, ciprofloxacin, ofloxacin, trovafloxacin, doxycycline, and clarithromycin using the shell vial assay. MICs of linezolid and clarithromycin ranged from 2 to 4 μg/ml; those of doxycycline, trovafloxacin, and ofloxacin ranged from 1 to 2 μg/ml; those of pefloxacin ranged from 1 to 4 μg/ml; and those of ciprofloxacin ranged from 4 to 8 μg/ml. Linezolid was effective in controlling intracellular parasites in cultures of Vero cells infected by C. burnetii. No bactericidal activity by linezolid was obtained against C.burnetii at 8 μg/ml.