AFB MDR Screen - Extra pulmonary samples

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).
LPA is based on DNA strip technology. This test may be used to detect M.tb and resistance towards rifampicin and isoniazid resistance in culture isolates.

Extrapulmonary tuberculosis (EPTB) diagnosis is difficult. This is due to its unusual clinical presentation, It usually causes a delay in or denial of therapy. Along with quick case discovery, it is critical in these circumstances to determine the MDR status early.

The Mycobacterium tuberculosis (MTB) complex and INH and Rifampicin resistance are both detected using the commonly available GenoType MTBDRplus assay version 2.0 (Hain Lifescience, Nehren, Germany).

Doctors hope to assess the role it plays in the diagnosis and detection of resistance. They do this by comparing this test's performance to the gold standard, which is culture. They also compare it to the composite reference standards (CRS) in the identification of EPTB. On negative and positive direct smear specimens, it generally had dubious benefits.

In cases when MDR-TB is highly suspect, experts recommend the Hain test. This is to identify the infection. They delay using traditional identification results to verify NTM. A positive Hain test results in a negative direct smear.

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