Antibiogram – MTB (PAS)

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.

Antibiogram test or Antimicrobial Susceptibility testing is performed to measure the susceptibility of microbes to certain antibiotics. Antibiogram – MTB (PAS) test checks for the sensitivity or resistance of MTB to the antibiotic – PAS. Para-aminosalicylic acid or PAS, a second-line drug belongs to the group of drugs called anti-tuberculosis medicines and is used in combination with other anti-tuberculosis medications like Isoniazid to treat active tuberculosis (TB) infection. It is bacteriostatic in nature, inhibits the synthesis of folic acid, and affects iron uptake. It plays a role in inhibiting the onset of resistance against streptomycin and isoniazid.

Cough for more than three weeks, chills, fever, night sweats, loss of appetite, weakness, and weight loss are some of the symptoms observed in individuals suffering from TB infection.

Why and when get tested with Antibiogram – MTB (PAS) test?
Antibiogram – MTB (PAS) test is used for determining and monitoring the drug susceptibility pattern of Mycobacterium tuberculosis, the bacterium that is responsible for Tuberculosis against the antibiotic – PAS or Para-aminosalicylic acid. This test is needed if an infection has shown to have antibiotic resistance, is otherwise hard to treat, or if there’s a bacterial or fungal infection that is not responding to standard treatments.

What is an Antibiogram test?
Antibiogram test or Antibiotic susceptibility testing (AST) is a widely-used technique for evaluating antibiotic resistance and determining the most effective antibiotic for treatment. This is achieved by observing the effect of a particular antibiotic on microbial growth. The treatment can be directed as per the knowledge of the microbe and its sensitivity to the drug.

What sample is required and what preparation is needed for this test?
A pure culture obtained from body fluids, sputum, bronchial alveolar lavage, cerebrospinal fluid (CSF), pus, tissue, biopsies, lymph nodes, abscess, and urine is 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).

What is the role of PAS in Tuberculosis treatment?
PAS is a second-line drug used in treating TB infections. It is bacteriostatic in nature, i.e. it works by inhibiting the growth of organisms that cause TB as well as plays a role in inhibiting the onset of resistance in bacteria against streptomycin and isoniazid.