Susceptibility of Legionella pneumophila to antimicrobial agents and the presence of the efflux pump LpeAB

Abstract

Our collection of L. pneumophila strains was susceptible to most antimicrobial agents except azithromycin. Gradient diffusion tests on BCYE-α test medium detected strains with reduced susceptibility to azithromycin. All L. pneumophila serogroup 1, ST1 strains showed reduced susceptibility to macrolides and contained the efflux pump component lpeAB. Reduced susceptibility to azithromycin in non-serogroup 1 strains may be due to the presence of an lpeAB efflux pump variant.