AFB DRUG SUSCEPTIBILITY FIRST LINE PANEL (HREZ), 4 DRUG BY MGIT in Mumbai

Tuberculosis is a chronic respiratory tract infection causing fever, cough and weight loss. It is commonly caused by Mycobacterium tuberculosis (M.tb). Many diagnostic techniques are available for diagnosis of tuberculosis which include staining, culture and nucleic acid detection.  Among nucleic acid detection techniques are polymerase chain reaction (PCR), Cartridge based nucleic acid amplification technique (CBNAAT), Line probe assay (LPA), Next generation sequencing (NGS).
This test offers sensitivity testing for the four first line antitubercular agents i.e., Isoniazid, Rifampicin, Ethambutol and pyrazinamide. This test is to be booked post a positive M.tb culture report by Mycobacterium growth indicatory tube (MGIT)

Acid-fast bacteria are also known as acid-fast bacilli. They are referred to as AFBs. These bacteria belong to a group that has the trait of acid fastness. This means the capacity to physically withstand acid-induced colour decolourization during staining operations. This distinctive quality aids in the classification and identification of acid-fast bacteria like Mycobacteria.

One of the diseases with a high mortality rate is tuberculosis (TB). This is brought on by the bacteria Mycobacterium tuberculosis (MTB). The microorganism is developing antibiotic resistance. So susceptibility testing is essential. The AFB drug susceptibility test evaluates how sensitive an AFB culture is to various classes of antibiotics. This is done to identify whether the bacteria are susceptible to them or not.

Test Overview

A chronic respiratory illness called tuberculosis results in the following symptoms -

• Fever.
• Coughing.
• Weight loss.

Usually, Mycobacterium tuberculosis is to blame (M.tb) for this. For the identification of tuberculosis, there are numerous diagnostic methods available. Some of these are,

• Staining.
• Culture.
• Nucleic acid detection.

Nucleic acid detection can be done using the following techniques -

• Polymerase chain reaction (PCR).
• Cartridge-based nucleic acid amplification technique (CBNAAT).
• Line probe assay (LPA).
• Next-generation sequencing (NGS).

The four first-line antitubercular drugs, isoniazid, rifampicin, ethambutol, and pyrazinamide, are all tested for sensitivity in this test. After a Mycobacterium growth indicatory tube (MGIT) reports a positive M.tb culture result, this test has to be scheduled. BY: Dr Vishal Wadhwa M.D, D.N.B Microbiology Medical Affairs

Written by: Dr Vishal Wadhwa, M.D, D.N.B Microbiology, Medical Affairs