Laboratory diagnosis of mycobacterial infections in patients with acquired immunodeficiency syndrome.

Disseminated mycobacterial infections are commonly seen in acquired immunodeficiency syndrome (AIDS) patients, and laboratory culture is the best method for diagnosing these infections. In addition to conventional agar media, we used BACTEC 12A (Johnston Laboratories, Inc., Towson, Md.) broth medium for culture. More isolates of Mycobacterium avium complex and Mycobacterium tuberculosis were recovered from 12A broth than from Lowenstein-Jensen or Middlebrook 7H11 agar. Also, the average detection time of these mycobacteria was the earliest with 12A broth. Stool examination has been helpful in diagnosing mycobacterial disease in AIDS patients, and in this study both acid-fast stain and culture of fecal material was necessary for efficient detection of mycobacteria. Another sensitive and practical method for detecting mycobacterial infections in patients with AIDS is the Isolator lysis-centrifugation system (Du Pont Co., Wilmington, Del.) which offers the advantage of quantitating the degree of mycobacteremia. Laboratories should be alerted to the possibility of mixed mycobacterial infection in patients with AIDS, and positive cultures should be repeatedly examined to detect coinfection with a slower-growing mycobacterium such as M. tuberculosis as well as M. avium complex.