ACID FAST BACILLI SMEAR Detail

The Acid Fast Bacilli (AFB) Smear is a rapid microscopic test used to detect the presence of acid-fast organisms, primarily Mycobacterium tuberculosis, the causative agent of tuberculosis (TB). The test involves staining a clinical specimen (commonly sputum) using the Ziehl-Neelsen or Auramine staining technique and examining it under a microscope.

AFB appear as bright red or fluorescent rods against a contrasting background due to their waxy cell wall, which retains the stain even after acid-alcohol decolorization.

This test is commonly recommended for:

• Suspected pulmonary or extrapulmonary TB

• Chronic cough with weight loss, fever, or night sweats

• Monitoring response to TB treatment

• Screening of high-risk populations (e.g., HIV-positive individuals)

While the AFB smear is a quick and cost-effective method, it is less sensitive than culture or molecular tests. A positive smear is highly suggestive of active TB and indicates the potential for transmission.