Legionella strains used in this study are listed in Table 1; they include 40 L. pneumophila and 26 non-L. pneumophila strains. L. gormanii and L. wadsworthii isolates resulted in no visible growth after 96 h incubation in BYE broth. The cumulative percentages, MIC₅₀, and MIC₉₀ values for the other 60 Legionella isolates, inhibited by different concentrations of the tested antimicrobials, are shown in Table 2. MIC₅₀ and MIC₉₀ values for macrolides were 0.062 and 0.25 mg/L, respectively, for AZM (range 0.031–0.5 mg/L); and 0.125 and 0.5 mg/L, respectively, for ERM (range 0.031–0.5 mg/L). MIC₅₀ and MIC₉₀ values for fluoroquinolones were 0.031 and 0.031 mg/L, respectively, for CIP and LEV (range 0.004–0.062 mg/L); and 0.031 and 0.062 mg/L, respectively, for MOX (range 0.004–0.125 mg/L). MIC₅₀ and MIC₉₀ values for tetracycline drugs were 8 and 16 mg/L, respectively, for DOC (range 0.5–16 mg/L); and 4 and 8 mg/L, respectively, for MIN (range 0.5–8 mg/L). MIC₅₀ and MIC₉₀ values for CTX were 4 and 8 mg/L, respectively (range 0.062–16 mg/L). With a MIC₉₀ of 0.031 mg/L, CIP and LEV were the most active drugs, while DOX (MIC₉₀ of 16 mg/L) was the least effective.