New biphasic culture system for isolation of mycobacteria from blood of patients with acquired immune deficiency syndrome.

A new biphasic medium consisting of a 7H11 agar slant and brain heart infusion broth liquid phase has been used for the past 10 months at the University of California at Los Angeles for isolation of Mycobacterium avium complex from blood. In 12 patients whose blood cultures were grown on this medium, the median time for isolation of M. avium complex was 7 days (range 6 to 15 days) compared with 21 to 27 days on a fungal medium and 28 to 38 days on routine blood culture medium. The system has provided a reliable and rapid way to obtain morphology and rapid identification of colonies produced from blood samples of patients with acquired immune deficiency syndrome, who are at high risk for M. avium complex mycobacteremia.