LT-Microscopy

NTEP laboratory network is comprising of National Reference Laboratories (NRLs), state level Intermediate reference laboratories (IRLs), Culture & Drug Susceptibility Testing (C & DST) laboratories and peripheral level laboratories. Peripheral level laboratories consist of  designated microscopy centres (DMCs) and NAAT labs.

NTEP has a quality assured laboratory network for bacteriological examination of sputum in a 3-tiered system.

Culture Drug Susceptibility Testing (CDST) is a growth-based phenotypic method used to check the susceptibility of Mycobacterium tuberculosis strains to various first and second line anti-TB drugs. Mycobacterial resistance to a particular drug is identified if there is growth observed in culture in presence of that drug.

Culturing TB Bacilli is well known and historic method for detection/ confirmation of Tuberculosis. It is a highly sensitive and specific phenotypic test; it can detect even a few viable bacilli in the sample (Upto 10 Colony Forming Units- CFUs). TB bacilli multiply in the culture and form colonies of TB bacilli which can are easily be identified.

Based on the growth media used Culture is divided in to two types, Solid and Liquid Culture methods. Types Culture:

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.

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:

• It is currently the most accessible and cheapest TB diagnostic test available under National TB Elimination Programme (NTEP) in India.
• It has the shortest turnaround time for diagnosis.
• It has high specificity. 

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.