Anti-Legionella activity of trovafloxacin compared with seven other antimicrobial agents including an intermethod...

The activity of trovafloxacin, a new fluorinated naphtheridone, was tested against 61 Legionella spp. isolates and compared with that of 4 fluoroquinolones, 2 macrolides, and rifampin. Trovafloxacin MICs were determined by a reference agar dilution method and E-test (Solna, Sweden) strips on buffered charcoal yeast extract agar. Among the fluoroquinolone compounds, the rank order of activity (on the basis of MIC90 results) determined with E-test strips was as follows: levofloxacin (MIC90, 0.094 microgram/ml) > trovafloxacin = sparfloxacin = ofloxacin (MIC90, 0.19 microgram/ml). Rifampin (MIC90, 0.008 microgram/ ml) and clarithromycin (MIC90, 0.032 microgram/ml) were the most potent of all drugs tested, and erythromycin and ciprofloxacin were the least active. In this study, the E-test strips with trovafloxacin were validated (100% of results +/- one log2 dilution compared to the reference value) for susceptibility testing with Legionella isolates.