[Antimicrobial susceptibility patterns of Legionella isolates in the environment and in patients].

BACKGROUND Antimicrobial susceptibility of Legionella spp. has rarely been studied in Korea. Therefore, we aimed to determine the susceptibility of Legionella spp. to various antibiotics. METHODS We assessed the antimicrobial susceptibility of 66 environmental and clinical Legionella isolates collected between January 2001 and December 2008 from Korea and Japan. The minimum inhibitory concentrations (MICs) of 6 antibiotics, namely, azithromycin, ciprofloxacin, clarithromycin, clindamycin, gatifloxacin, and gemifloxacin were determined by the broth microdilution method using buffered starch yeast extract broth. RESULTS The MIC ranges of the 6 antibiotics used against the Legionella isolates were as follows: 0.004-0.062 microg/mL (azithromycin), 0.002-0.5 microg/mL (ciprofloxacin), 0.004-0.5 microg/mL (clarithromycin), 0.12-4 microg/mL (clindamycin), 0.002-0.12 microg/mL (gatifloxacin), and 0.008-1 microg/mL (gemifloxacin). CONCLUSIONS Legionella spp. isolates from Korea and Japan were most susceptible to gatifloxacin. Azithromycin, clarithromycin, ciprofloxacin, and gemifloxacin were also effective for treating legionellosis.