EVALUATION OF THE MYCOAKT LATEX AGGLUTINATION-TEST FOR RAPID DIAGNOSIS OF MYCOBACTERIUM-AVIUM COMPLEX INFECTIONS

Rapid diagnosis of Mycobacterium avium complex (MAC) bacteremia is imp ortant for management of patients with the acquired immunodeficiency s yndrome who have disseminated MAC. The purpose of this study was to de termine the reliability of the MycoAKT latex agglutination test for di rect detection of MAC in positive mycobacterial blood cultures. First, colonies of isolates of previously identified mycobacteria, including 35 MAC, were tested. Of the 55 isolates evaluated, 33 were identified as MAC by the latex test, including 31 of the known MAC and 2 M. chel onae (sensitivity, 88.6%; specificity, 90.0%). Second, broth from 20 E SP II and 20 BACTEC 12B bottles seeded with isolates of MAC were teste d. Aliquots from 19 (95%) ESP II cultures and 16 (80%) 12B cultures we re positive by the latex test. In phase 3, broth from 115 signal-posit ive ESP II blood cultures were tested by latex agglutination. Forty-th ree subcultures from these bottles grew mycobacteria (41 MAC and 2 Myc obacterium tuberculosis complex); the remainder grew no organisms. Bro th from 40 of the blood cultures (39 that grew MAC and 1 from which no organisms were recovered) were latex positive; thus, the sensitivity, specificity, and positive and negative predictive values of the latex test for direct identification of MAC in ESP II blood cultures were 9 5.1, 98.6, 97.5, and 97.3%, respectively. The mean time to detection o f MAC was 14.6 days (range, 6-34 days) with the direct latex test, com pared with 18.3 days (range, 9-36 days) with subculture and probe (p<0 .05). (C) 1998 Elsevier Science Inc.