After exposure to infective droplets containing M.TB, only a small proportion gets infected and further progresses to active TB disease.

To discuss how TB progresses to TB disease following TB exposure in some individuals. 

To bring out the difference between TB exposure, TB Infection and the TB disease following TB exposure.

The Senior TB Laboratory Supervisor (STLS) is the person responsible for monitoring the day-to-day activities of all the microscopy centres and nucleic acid amplification test (NAAT) sites and is thus essential to the success of the National TB Elimination Programme (NTEP). They also ensure the quality of TB diagnostic services.

Roles of STLS at the DMC

May use Nikshay screen recordings available

For laboratory diagnosis of TB, different biological specimens are used.

Pulmonary TB: Sputum sample is used. Sputum is a thick fluid produced in the lungs and in the adjacent airways. Normally, a spot sample and a fresh morning sample is preferred for the bacteriological examination of sputum.

Extra Pulmonary TB:

Resources:

Presumptive TB case refers to a patient who presents with symptoms or signs suggestive of TB disease (previously known as a TB suspect) and where further diagnostic workup including bacteriological investigation is required.

 Presumptive TB can be categorized into

1. Presumptive Pulmonary TB (P TB) - Symptoms are directly related to lungs (Cough, hemoptysis)

2. Presumptive Extra Pulmonary TB (EP TB) - Symptoms/ signs are specific to an extra pulmonary site (example: Lymph node swelling)

The National Tuberculosis (TB) Elimination Program (NTEP) has a network of Nucleic Acid Amplification Tests (NAAT) laboratories coupled with Designated Microscopy Centers (DMCs) to form the backbone of the diagnostic component of TB services.

Nucleic Acid Amplification Tests (NAAT) laboratories includes Cartridge-based NAAT (CBNAAT) and TrueNat tests. These tests detect tuberculosis as well as rifampicin resistance and are more sensitive than smear microscopy.

Discuss NAAT as a class of TB diagnostic technology and their various types.

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.