Fluorescent Smear

Tuberculosis or TB, caused by the bacterium Mycobacterium tuberculosis (MTB) is one of the diseases with a high fatality rate that mostly affects the lungs (Pulmonary TB) and sometimes infects other parts of the body like pleura, joints, abdomen, skin, etc (Non-pulmonary TB). The disease spreads mainly when the bacteria are dispersed in the air when an infected person spits, coughs, or sneezes. Due to the slow growth pattern and drug resistance, the disease presents a major challenge in terms of treatment and quick diagnostic techniques.

MTB belongs to the group called Acid-fast bacteria or acid-fast bacilli (AFB). These are a group of bacteria sharing the property of acid fastness, that is the physical ability to resist decolorization by acids during staining procedures. This unique feature serves as a distinguishing ability in classifying and detecting acid-fast bacteria like Mycobacteria.

Direct microscopic examination plays a key role in the diagnosis and monitoring of treatment in TB-infected patients. The presence of AFB in microscopically examined smears provides bacteriological evidence of Mycobacterium, the bacterium responsible for Tuberculosis in a clinical specimen. The fluorescent Smear test uses a fluorescent stain and iLED microscopy for detecting the fluorescence emitted by the bacteria. The test provides a count of bacilli in accordance with India’s National Tuberculosis Elimination Programme, allowing bacterial load in the sample to be estimated and further tests to be guided.

Why Get Tested with Fluorescent Smear?
A fluorescent Smear test is an iLED microscopic technique used for the detection of Mycobacterium tuberculosis, the bacterium responsible for Tuberculosis.

What sample is required and what preparation is needed for this test?
A number of samples including body fluids, sputum, bronchial alveolar lavage, cerebrospinal fluid (CSF), pus, tissue, biopsies, lymph nodes, abscess, and urine can be used for performing this test. There is no special preparation required before getting this test.

What are the types of drug-resistant TB?
Drug-resistant tuberculosis infection, caused by drug-resistant Mycobacterium tuberculosis (MTB) bacterium is divided into the following categories

• Multidrug-resistant or MDR-TB: MDR-TB is the TB infection caused by MTB that is resistant to the most potent drugs used in TB treatment – isoniazid and rifampin.
• Extensively drug-resistant or XDR-TB: XDR-TB is the TB infection caused by MTB that is resistant to most commonly used drugs used in TB treatment like isoniazid and rifampin, plus any fluoroquinolone as well as at least one of the three injectable second-line drugs (amikacin, kanamycin, and capreomycin).

Is there any vaccine for Tuberculosis? Can TB be cured?
Bacille Calmette-Guérin (BCG) is the vaccine available for prevention of TB infection. TB is a preventable and curable disease. Active infections can be treated with a 6-month course of antimicrobial drugs.

What are the advantages of using Fluorescent Smear?
A fluorescent smear test, used for the detection of Mycobacterium tuberculosis, the bacterium responsible for Tuberculosis has the following advantages

• Better sensitivity
• Examination at lower magnification enables visualizing larger area, thereby saving time as well as effort