The homogenate was decontaminated for 4 h i 0.75% HPC and then centrifuged at 900 x g for 30 min. The pellet was resuspended in 1 ml of Middlebrook 7H9 broth (Difco Laboratories, Detroit, Mich.), and 5 drops were inoculated onto HEYM slants and incubated as described above. Milk samples were centrifuged at 900 x g for 30 min, and the supernatant was discarded.