Growth of 28 Legionella species on selective culture media: a comparative study

Abstract

We compared the growth of 28 Legionella spp. on four manufacturers' buffered charcoal-yeast extract (BCYE) agar media and selective BCYE media that contained polymyxin B, anisomycin, and vancomycin or cefamandole. With BCYE as a "gold standard," growth for Legionella pneumophila was significantly better than for the nonpneumophila species on all media tested. L. pneumophila and 24 other Legionella spp. grew on vancomycin-containing media, while L. santicrucis, L. rubrilucens, and L. erythra grew poorly. In contrast, 11 of 28 species (notably L. micdadei and L. bozemanii) did not grow on cefamandole-containing media and 8 of 28 species only grew marginally. We demonstrated that selective BCYE media that contain vancomycin or cefamandole may not support the growth of all Legionella spp. One commercial manufacturer's media were consistently suboptimal. Laboratories should not rely on a manufacturer's quality control testing in lieu of their own.