CDST_LT: General concepts

The National TB Elimination Programme (NTEP) has strengthened sputum collection and transport for laboratory testing by building capacity for decentralised collection.

• The provision for sputum collection and transport is used to establish linkages for giving diagnostic access to patients who cannot reach the health facilities. 
• To increase access and coverage of services, designated sputum collection centres are also established for collecting and transporting sputum to the nearby laboratory.

Presumptive TB patients attending Peripheral Health Institutions (PHIs) other than Designated Microscopic Centres (DMCs) are either referred to the nearest DMC for sputum examination or their sputum specimens are collected and transported to the DMC as per guidelines. 

• The patient is given these options as per their convenience to minimise the possible delay in diagnosis and initiation of treatment or avoid repeated visits by the patient.
• In case the patient is not able to travel to the DMC, then the spot sample is collected at the nearest health facility/ sputum collection centre/ sputum collection booths and transported to the DMC.

The need for sample collection can be categorized broadly into two categories:

1. When samples are sent to the DMC

- Some PHI/ sub-centres/ health and wellness centres function as sample collection centres. 

- Sputum collected from referring health facilities needs to be transported to the nearest DMC.

2. When DMC has to collect and transport samples for testing/ follow-up/ resistance testing to higher laboratories

- If the Nucleic Acid Amplification Testing (NAAT) facility is not available at the health facility, the DMC may also need to collect and send the sample to the nearest linked facility for NAAT testing.

- If NAAT is available at DMC and Mycobacterium tuberculosis (MTB) is detected, the second sample needs to be transported to the Culture and Drug Susceptibility Testing (C&DST) lab. If the NAAT result suggests rifampicin-sensitive, a second sample is sent for First-line Line Probe Assay (FL-LPA) to look for H-mono/ poly resistance.

- Extrapulmonary samples have to be appropriately collected at the PHI/HF and transported for testing to NAAT/ culture facilities.

Resources

• Training Module (1-4) for Program Managers and Medical Officers, NTEP, MoHFW, 2020.  

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