FIG. 3.

Coculture of Acanthomoebae with strains of Legionella. (A) Amoeba liquid cocultures were set up in saline with approximately 10⁴ amoebae/ml and 10³ CFU (each) of L. pneumophila serogroup 1 (Philadelphia) (⧫), L. longbeachae serogroup 1 ATCC 33462 (▪), B10 (▵), A5H5 (•), and B8 (×) per ml. Samples were taken at various time intervals, and the number of Legionella organisms was determined by plating on selective media. Each time point represents the mean number of CFU recovered, and the vertical bars indicate standard deviations. (B) Amoebae were cocultured in an artificial potting mix system with strains of Legionella as indicated above. Numbers of viable Legionella organisms were determined at various time points by treatment of the soil sample with acid and plating on selective media. The experiments shown are representative of two independent experiments.