is a waterborne pathogen that causes a severe form of pneumonia called Legionnaires’ diseases, which is normally acquired by inhalation of aerosols containing originating from natural and man-made water systems. The aim of this study was to describe the level of antimicrobial susceptibility of environmental spp. strains to preferred and recommended therapeutic agents to treat disease. The minimum inhibitory concentrations (MICs) of 60 environmental spp. strains were tested using the broth dilution method. Susceptibility testing was performed for 12 antimicrobial agents: macrolides (erythromycin, azithromycin [AZI], and clarithromycin [CLA]), fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin, and gemifloxacin), a ketolide (telithromycin), cefotaxime (CEF), tigecycline (TIG), doxycycline (DOX), and rifampicin (RIF). All tested strains of spp. were inhibited by low concentrations of fluoroquinolones and macrolides. Regarding the macrolides, CLA was the most active antibiotic, and AZI was the least active. RIF was the most effective antibiotic against the isolates . All isolates were inhibited by the following antibiotics (in decreasing order of their MICs): DOX>CEF>TIG. No resistance against these drugs was detected, and all isolates were inhibited by low concentrations of the tested antibiotics. Susceptibility testing of environmental spp. isolates must be monitored often to detect and evaluate the possible development of antibiotic resistance.

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