Primary isolation media for Legionnaires disease bacterium

Abstract

Yolk sac suspensions infected with the Legionnaires disease bacterium (LDB) were plated onto 17 different bacteriological agar media. The LDB grew only on Mueller-Hinton agar supplemented with 1% IsoVitaleX and 1% hemoglobin (MH-IH). This medium was subsequently analyzed to determine the components required to support growth of the LDB. L-Cysteine hydrochloride can replace the IsoVitaleX reagent, and soluble ferric pyrophosphate can replace hemoglobin. A new medium, F-G agar, was formulated incorporating these chemicals. Different culture conditions (oxygen tension, temperature and pH) were also evaluated. The LDB grew optimally at 35.degree. C under 2.5% CO2 on the F-G agar adjusted to pH 6.9. When infected tissues were inoculated onto F-G agar and MH-IH, the F-G agar produced colonies of the LDB more rapidly and in greater numbers than did MH-IH.