Line Probe Assay (LPA) is a rapid molecular test available at centralised laboratories.
The assay is based on Polymerase Chain Reaction (PCR) that can simultaneously detect Mycobacterium tuberculosis complex as well as drug sensitivity to anti-TB drugs.
The tests are performed using Trueprep AUTO Sample Pre-treatment and Prep kits and Truenat micro-PCR chips.
To detect M. tuberculosis, the Truenat MTB chip amplifies a portion of the ribonucleoside-diphosphate reductase gene, nrdB with a Limit of Detection (LOD) of about 100 Colony Forming Units (CFU)/ml sputum sample.
DNA extraction and detection of M. tuberculosis takes approximately one hour.
Microscopy is a TB diagnostic technology that utilizes the acid-fastness property of Mycobacterium tuberculosis to visualize it under a microscope. Results of sputum smear microscopy can either be smear-negative, or smear-positive (with various grades).
Advantages:
Limitations:
Nikshay is an Integrated ICT system for TB patient management and care in India. Nikshay was launched in 2012 and since then, various improvements have been made in the system.
Nikshay provides-
National Tuberculosis Elimination Programme (NTEP) strives for all presumptive TB patients to be microbiologically confirmed. Under NTEP, the acceptable methods for microbiological diagnosis of TB are:
Screening for active tuberculosis (TB) a process to filter out people who are less likely to have TB, from a group. Screened positive people are likely to have TB and are confirmed subsequently using a TB diagnostic test. This will allow finite diagnostic testing resources to be used on the remaining.
TB cases are generally classified on the basis of previous history of TB treatment into New and previously treated cases.
New case - A TB patient who has never had treatment for TB or has taken anti-TB drugs for less than one month is considered as a new case.
Previously treated patients have received 1 month or more of anti-TB drugs in the past. They could be further classified as:
TB Infection (or previously known as Latent TB infection) is a stage in between uninfected and having active TB. In this stage the person has no symptoms and can only be identified using laboratory tests.
The vast majority of infected people may never develop TB disease. However, to achieve TB elimination, it is important to treat TB infection in people at risk of developing active TB disease.
The disposable, single-use CBNAAT cartridge is a closed system unit to hold the samples and reagents. Inside of a CBNAAT Cartridge (CBNAAT operator manual). Each cartridge consists of the following components:
It is important that patients receive their positive/negative test results and an adequate explanation of the results in a timely manner.
Time required for different Laboratory test results include:
1. Smear microscopy/follow up:1 day
2. Nucleic Acid Amplification Test (NAAT) (CBNAAT/Truenat):1-2 days
3. Line Probe Assay (LPA): 2-3 days
4. Liquid Culture DST (Drug Susceptibility testing): 22-48 days
