High predictive value of the acid-fast smear for Mycobacterium tuberculosis despite the high prevalence of Mycobacterium avium complex in respiratory specimens.
The value of the smear for acid-fast bacilli in predicting pulmonary tuberculosis is unclear in a setting where there is a high prevalence of Mycobacterium avium complex in respiratory specimens. To evaluate the impact of a high prevalence of M. avium complex on the predictive value of the acid-fast bacilli smear for tuberculosis, we reviewed findings on smears and results of cultures over a 3-year period at a hospital where M. avium complex is the predominant mycobacterial isolate. In this setting, the predictive value of the acid-fast bacilli smear for Mycobacterium tuberculosis was 92% for expectorated sputum specimens, 71% for induced sputum specimens, and 71% for bronchoalveolar lavage specimens. When multiple specimens collected from the same patient were excluded from the data base, the predictive values were 87%, 70%, and 71%, respectively. Smears of sputum samples were positive at the same rate for patients with tuberculosis who had AIDS and for patients with tuberculosis who did not have AIDS.
Yajko
D M
DM
Department of Laboratory Medicine, University of California, San Francisco.
Nassos
P S
PS
Sanders
C A
CA
Madej
J J
JJ
Hadley
W K
WK
D000163:Acquired Immunodeficiency Syndrome / Q000150:complications; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology*; D006801:Humans; D015269:Mycobacterium avium Complex / Q000302:isolation & purification*; D015270:Mycobacterium avium-intracellulare Infection / Q000175:diagnosis* / Q000382:microbiology; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D011237:Predictive Value of Tests; D015995:Prevalence; D013183:Sputum / Q000382:microbiology; D013194:Staining and Labeling; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000382:microbiology