DR-TB HIV Coordinator: Diagnostic Network and Hierarchy

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.

Figure: Laboratory network of NTEP

Resources:

• TB India Report 2021

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Under the National Tuberculosis Elimination Programme (NTEP), many labs are established at the regional level within states for providing Culture and Drug Susceptibility Testing (C&DST) facilities for presumptive TB/DRTB and for TB/DRTB patients. C&DST laboratories are mostly located in intermediate reference laboratories (IRLs) or medical colleges. There are 42 C&DST laboratories established under the programme in different geographies. Dedicated human resources are provided for the laboratories under the programme. Districts are linked with laboratories for providing facilities for Culture and DST using: Phenotypic Methods (Solid – Lowenstein Jensen (LJ), and Liquid Culture – Mycobacteria Growth Indicator Tube (MGIT)) Genotypic technology (Line Probe Assay (LPA) and Cartridge Based Nucleic Acid Amplification Test (CBNAAT))

Figure: Culture and Drug Susceptibility Testing (C&DST) facility, Source: The Foundation For Innovative New Diagnostics (FIND)

Resources

• Guidelines for Programmatic Management of Drug Resistant TB in India, 2021
• Training Modules (1-4) for Programme Managers and Medical Officers; New Delhi, India: Central TB Division, July 2020

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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.

Functions of Nucleic Acid Amplification Test (NAAT) Laboratories:

1. Acting as a hub for collection of samples from public and private health facilities (spokes)
2. Universal Drug Susceptibility Testing (UDST) to rule out rifampicin resistance among confirmed TB patients
3. Timely provision of NAAT test result to the TB patient, medical officer of the concerned health facility and NTEP staff for related actions
4. Acting as a sample dispatch center for the Culture DST laboratory for subsequent processing of samples for first-line line probe assay (LPA) and second-line drug resistance testing utilizing second line LPA and liquid culture DST
5. Recording and reporting including digitization of diagnostic process from collection to test result in NTEP Nikshay portal and Laboratory Information Management System
6. Management of supplies and logistic associated with laboratory logistic (CBNAAT cartridges and TrueNAT chips) and reporting any additional requirement thereof
7. Supporting the quality assurance activities undertaken by District or Intermediate Reference Laboratory under NTEP
8. Support health system in carrying out special drives for vulnerable and at-risk population and their testing directly by CBNAAT (slum population, diabetic population, smoker, malnourished people, patients of silicosis and kidney dialysis etc.)

Resources

• RNTCP Technical and Operational Guidelines for TB Control in India, 2016.
• Guidelines for Programmatic Management of Drug Resistant Tuberculosis in India, 2021.

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Diagnostic services are provided free of cost at all public health laboratories, for patient referrals from the private sector. Laboratory services are also purchased from certified private sector laboratories through partnership schemes.

• The Initiative for Promoting Affordable and Quality TB Tests (IPAQT) was initiated in 2013 to bring World Health Organization (WHO)-approved tuberculosis tests at affordable prices to patients in the private sector. 
• IPAQT is an initiative of not-for-profit stakeholders and private sector labs/ hospitals (collection centres) with a pan-India presence. IPAQT brought together various private laboratories with the support of test manufacturers and other major stakeholders to:
  • Bring down the price for quality TB tests by up to 50% in the private sector (see table below)
  • Promote the use of these tests by building awareness among health providers, laboratories and patients

It's the responsibility of District TB Officers (DTOs) to ensure that, patients diagnosed through IPAQT laboratories are notified in the National TB Elimination Programme (NTEP) surveillance system and appropriate public health actions are initiated.

Resources

• Guidelines for Programmatic Management of Drug-resistant TB in India, 2021.
• IPAQT.

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Sputum microscopy diagnostic services under the National TB Elimination Programme (NTEP) are provided by the Designated Microscopy Centres (DMCs) established at the Peripheral Health Institution (PHI) level, where a functional binocular microscope and a trained Laboratory Technician (LT) is available. Light Emission Diode Fluorescent microscopes are provided to high-load PHI-DMCs such as that of the medical colleges. 

Based on latest directives, a DMCs may be established at all PHIs (Public and Private) of the country as needed. It is mandatory to have a DMC at all medical colleges in the country.

As molecular technologies like Truenat are also used in DMCs, NTEP has planned to rename DMCs as TB Diagnosis Centres (TDCs).

Criteria to be a DMC

The DMCs should satisfy the following criteria:

1. NTEP-trained Laboratory Technician (LT) should be present.
2. A functional binocular microscope should be present in the laboratory.
3. Physical infrastructure in the laboratory should meet NTEP guidelines.
4. Daily new adult outpatient cases of at least 60-100 and/or workload of at least 3-5 sputum smears per day for the LT in the laboratory.

DMCs in the public sector, at the onset of the programme, are provided with funds to undertake minor civil works to build up their physical infrastructure and are provided with binocular microscopes.

Human Resources Norms

• For the purpose of NTEP, a PHI is a health facility which is manned by at least a Medical Officer (MO).
• In addition to the MO and LT, there is 1 TB Health Visitor (TBHV) per one lakh urban population to support the urban TB control activities.

Other Criteria

Microscopy Centres may be established beyond population norms in medical colleges, corporate hospitals, Employee State Insurance Corporation (ESIC), railways, Non-government organisations (NGOs), private hospitals, Ayushman Bharat - Health and Wellness Centres (AB-HWCs), etc.

Before designating a DMC in other sectors, there should be a formal agreement by the hospital/ laboratory to take part in the External Quality Assurance (EQA) and to allow the concerned NTEP staff to supervise as per the NTEP guidelines.

If the above criteria are met by any private laboratory, the lab is considered for establishing a DMC.

• To provide better access for diagnosis of TB, all PHIs, wherever LTs and binocular microscopes are available, can be upgraded to a DMC irrespective of the population norms or OPD attendance.
• All DMCs should comply with the Quality Assurance (QA) mechanisms as per the EQA guidelines.

Resources

• NTEP Training Modules 1-4 for Programme Managers & Medical Officers, 2020.
• Operational Guidelines for TB Services at Ayushman Bharat Health and Wellness Centres.

Assessment Questions

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To increase access to diagnostic services, NTEP has a provision for sputum collection centres in areas where the health facility is not equipped with key requirements to conduct sputum microscopy, molecular tests, drug susceptibility testing or follow up examinations.

Sputum collection centres are dedicated locations where sputum samples are collected, packaged and then transported to nearby TB diagnostic centres. It could be attached to any near-by health-facility as well.

Requirements of a Sputum Collection Centre

To function as sputum collection centres, the following is essential:

• Linkage/ mapping (time and distance) to testing laboratory
• Availability of adequate number of sputum cups and falcon tubes, logistics for sample packaging and transport
• Identification of open areas for sputum collection
• Staff trained in NTEP guidelines on sputum collection, sample packaging and transport, complete and correct documentation of laboratory request form, and infection control practices
• Feasibility and financial measures required for sample transport
• Inclusion of local volunteers, courier services, sample transportation under National Health Mission Free Diagnostic Services or other mechanisms as decided by the state/district
• Availability of Information, Education and Communication (IEC) material, training modules, and job-aids
   

 Sputum collection centres are established in:

• Ayushman Bharat Health and Wellness Centres/Sub-centres
• Urban primary health centres
• Tribal, hilly, desert and difficult-to-reach areas of the country

Resources

• Training Modules for Programme Managers and Medical Officers
• Operational Guidelines for TB Services at Ayushman Bharat Health and Wellness Centres
• Mycobacteriology Laboratory Manual, GLI Initiative, 2014

Assessment:

• Good quality sputum collection is of paramount importance in tuberculosis diagnosis.
• Once a person is identified as presumptive TB, s/he is referred to the Designated Microscopy Centre (DMC) for sputum collection.
• For TB diagnosis two sputum samples are collected - one is the supervised ‘spot’ sample collected at the DMC (labelled Specimen A) and the other is the early morning sample collected by patient themselves at his/her home (labelled Specimen B).
• If the patient is coming from a long distance or s/he is unlikely to return to give the second specimen, two spot specimens may be collected with a gap of at least one hour.

Figure: Flowchart for Sputum Collection and Transport

Sputum Collection

• The (NTEP) request form required for the biological specimen examination need to be filled.
• The Lab Technician (LT) should instruct the patient to thoroughly rinse the mouth with clean water and demonstrate to inhale deeply 2-3 times and cough out the sputum from the depth of the chest into a sterile 50 ml sputum container, in a well-ventilated space.
• After collecting the sputum, close the lid of the containers and wipe the surface of the tube with 5% phenol to disinfect and allow it to air dry.
• Label the tubes with patient details, date and time of collection, specimen identification, lab no. using a permanent marker.

Sputum Transport

• The sputum collected should be transported immediately to the Nucleic Acid Amplification Testing (NAAT)/ Culture and Drug Susceptibility Testing (C&DST) laboratory. In case of any unavoidable delays, the sample should be refrigerated.
• The programme mandates triple layer packaging for the transport of the sputum specimens.
• Firstly, seal the joint between the cap and neck of the sputum containers with a parafilm strip (primary receptacle package).
• Wrap the sputum containers individually in absorbent cotton, place them in a zip lock pouch and secure them with a rubber band (secondary receptacle package).
• Fold and place the NTEP request form in another zip lock pouch.
• Place the zip lock pouch with sputum containers in a thermocol box along with two pre-frozen coolant gel packs and the zip lock pouch with the NTEP request form is placed on top.
• The dimensions of the thermocol box used for sputum transport are: thickness - 2.5 cm; Outer dimensions: length - 18.5 cm, breadth - 13 cm, height - 12 cm (without lid), height -14 cm (with lid); Inner dimensions: length - 14.5 cm, breadth - 8 cm, height - 12 cm (without lid), height - 13 cm (with inner part of lid).
• The coolant gel packs should be conditioned in the deep freezer in a temperature between -20 to -15^o C for a minimum 48 hours to a maximum 72 hours before use so that they can maintain a temperature between 12-20^o C for up to approximately 48 hours in tightly packed thermocol boxes while the average outside temperature is 35^o C. 
• Seal the thermocol box with duct tape and affix ‘To’ and ‘From’ address, biohazard sticker on the box (tertiary receptacle package).
• Weight of the fully packed consignment box should be up to 400 grams and the thermocol boxes and gel packs should not be reused. 
• Transport the box through NTEP identified courier/ speed post service.

Resources

• Training Module (1-4) for Programme Managers and Medical Officers, NTEP, MoHFW, 2020.
• Guidelines for Programmatic Management of Drug-resistant TB in India, 2021.
• Module for Laboratory Technician, CTD, MoHFW, India, 2005.

Assessment