LT-Microscopy & NAAT

Biological specimen/ samples collected on reaching a TB testing laboratory needs to be formally received. The sample may be handed over by agents(couriers, health staff/ volunteers, patient representatives) or by patients themselves. The formal receipt of sample enables further processes such as testing and communication of results back to the patient. If the sample is successfully received, the appropriate testing process is initiated using the sample, else it is rejected and a fresh sample requested. 

The use of appropriate Personal Protective Equipment (PPE) in a TB laboratory is determined by risk assessment (according to the procedure and suspected pathogen).

Designated Microscopy Centres (DMCs) are low-risk TB laboratories, hence PPE should be used as follows:

Counselling before initiating treatment for a patient. is an important component of the National TB Elimination Programme (NTEP). The patient is counselled along with his family by the health staff.

Counselling is done on the following points:

When the referring health facility receives the test results from the DMC, the results are communicated to the patient through NTEP supervisors/health facility staff/Medical Officer.

Both Positive and negative results need to be communicated to the patient. For negative results, counselling for further evaluation and testing need to be done for the symptoms.

Communication as a tool embodies attitudes, behavior, body language, style, method of presentation, quality of listening and perceptions and interpretations.

The Medical Officer (MO) of the referring health facility initiates TB treatment on receipt of the diagnostic test results. All efforts are made to initiate the treatment at the earliest.

The treatment regimen is decided based on the type of patient and TB (based on drug sensitivity pattern, i.e., drug-sensitive TB or H-mono/ poly resistance, history of adverse drug reaction to anti-TB drugs).

Sputum collection centres collect, package and then transport samples to nearby TB diagnostic centres/ Designated Microscopy Centre (DMC).

Sputum is collected and packaged utilizing the triple-layer packing as per National TB Elimination Programme (NTEP) Guidelines.

All efforts must be made to have decentralised local arrangements for transporting the specimens to the TB detection centre (TDC). If a proper transport mechanism for collected specimen is in place, it spares the patients from travelling to the laboratory.

The sputum sample is packaged in triple layers in such a manner that it arrives at the destination in good condition and presents no hazard to the transporter.

Transporter/ personnel transporting the sample should be sensitized by the National TB Elimination Programme (NTEP) staff prior to engagement.

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.

Smears stained with the fluorescent dye, Auramine, are read with a Light Emitting Diode Fluorescence Microscope (LED-FM).

The manner and quality of smear reading has a major impact on the result of sputum smear microscopy and case detection. Each slide needs to be examined for at least 5 full minutes or 100 fields need to be examined. 

The overall process of reading a smear is outlined in the figure below:

Figure: Process of reading a smear

Resources: