Acid-Fast Bacilli (AFB) Smear

Microbiology

Normal Reference Ranges

Adult

Negative Qualitative

Pediatric

Negative Qualitative

Clinical Significance

Essential rapid test for suspected pulmonary Tuberculosis. Requires 3 morning sputum samples. If positive, patient requires strict airborne isolation.

Causes of High

  • Tuberculosis (Mycobacterium tuberculosis)
  • Nontuberculous mycobacteria (MAC)
  • Nocardia

Causes of Low

  • Normal finding