Diagnosis for MAC include AFB sputum for pulmonary disease and AFB blood for disseminated disease
- related: mycobactrium avium MAC
- tags: #permanent
- source: uptodate
Microbiologic criteria for nonTB mycobacterium (MAC):
- for pulmonary disease:
- screening: obtain 3 separate AFB with BAL can count as one of the cultures
- diagnosis: positive culture from 2 separate sputum or 1 BAL
- for disseminated disease: blood culture for AFB
Current guidelines recommend the presence of clinical criteria in addition to microbiological confirmation to diagnose pulmonary MAC disease. Since MAC can contaminate or colonize sputum, confirmation of pulmonary MAC disease requires at least 2 positive sputum cultures. However, M. tuberculosis positive sputum is always pathologic and should be treated. This patient meets the clinical criteria for pulmonary MAC, but has only one positive sputum culture. A repeat sputum sample is needed to establish the diagnosis, and if the repeat sputum is negative, a positive culture from a BAL specimen would then be required.