Lack of resistance to erythromycin, rifampicin and ciprofloxacin in 98 clinical isolates of Legionella pneumophila.

Ninety-eight consecutive clinical isolates of Legionella pneumophila were tested for erythromycin, rifampicin and ciprofloxacin susceptibility. MICs, determined by agar dilution testing, were in the range 0.06-1 mg/L of erythromycin, 0.007-0.015 mg/L of rifampicin and 0.015-0.03 mg/L of ciprofloxacin. No resistance against the antibiotics tested was detected. It is thus likely that therapeutic failures in legionnaires' disease are not related to the emergence of resistance against commonly used antimicrobial agents.