diagnosis of Mycobacterium avium intracellulare

Introduction

Must differentiate colonizers from true pathogens.

American Thoracic Society (1997):

• Compatible clinical & radiographic evidence, plus:
  • 3 positive sputum cultures (smears negative) OR
  • 2 positive sputum cultures + 1 positive smear OR
  • A single culture of a sterile fluid/specimen
    • Blood
    • Bone Marrow
    • CSF

Bacteriologic Criteria:

• bronchoalveolar lavage (BAL)
• positive culture with high-grade (2+) growth or smear

Tissue Biopsy:

• any growth from bronchopulmonary tissue
• granuloma or AFB on biopsy, with 1 positive culture
• any growth from sterile extrapulmonary site
• Bone Marrow, Lymph Nodes, Liver

Radiographic Criteria:

• Chest X-ray:
  • Thin-walled cavitary infiltrates (BUL)
  • Nodular infiltrates without cavities, usually associated with bronchiectasis (RML, lingula)
  • Isolated nodules
• Chest CT:
  • Similar infiltrates
  • Mediastinal lymphadenopathy