LT-Microscopy & NAAT

The CBNAAT System automatically performs internal quality control for each sample. 

During each test, the system uses the following inbuilt controls:

System Check Control (SCC)

• Checks integrity of the instrument, cartridges and PCR reagents.

Sample Processing Control (SPC)

• Ensures that a sample is correctly processed.
• Included in the cartridge and is processed with the sample. The DNA is detected by a PCR assay.

Probe Check Control (PCC)

The Laboratory Technician (LT) must safely discard contaminated, biohazard waste generated by tuberculosis (TB) laboratories. This waste must be discarded along with the overall waste of the health facility in which TB services are provided.

There are 2 types of waste generated from DMC laboratory settings:

1. Sputum containers with specimen and wooden sticks
2. Stained slides

Disposal of Sputum Cups with Left-over Specimen, Lids and Wooden Sticks

A cold chain is a system of transporting and storing TB specimens at optimum temperature while being transported from the peripheral health institutions to the diagnostic labs to reduce the growth of contaminating endogenous respiratory organisms.

Cold chain requirements for transportation of TB diagnostic specimens are (Figure 1):

Disposal of infectious samples and used cartridges in Truenat laboratories is an essential activity which needs to be performed to keep everyone safe and prevent TB infection in healthcare workers.

General biosafety requirements for Truenat laboratory include:

External Quality Assurance (EQA) ensures quality of Truenat laboratory is maintained by comparing their results through retesting and panel testing by a higher level laboratory (Intermediate Reference Laboratory (IRL)/ National Reference Laboratory (NRL)).

EQA for Truenat laboratory is done by:

On completion of test run, the Test Result Screen displays the results for:

• Detection of Mycobacterium tuberculosis (Truenat MTB)
  • “DETECTED” for Positive result, Cycle Threshold (Ct) value, Colony Forming Units per milliliter (CFU/ ml)
  • “NOT DETECTED” for Negative result
  • “Valid”/ “Invalid” for test validity based on amplification of Internal Positive Control (IPC)
  • “Error” for test failure

Truenat MTB Assay results are visualized:

• During testing
• Completion of test

Test Status Screen (Figure 1)

Results visualization during testing include:

Procedure

Equipment and reagents

• Truelab Uno/ Duo/ Quattro Real Time Quantitative micro–PCR analyzer
• Truenat MTB micro-PCR kit
• Truenat MTB Rif micro-PCR kit
• Truepet fixed volume (6 μl) precision micropipette

Amplification and detection of Mycobacterium tuberculosis (MTB)

The extra-pulmonary samples (Non-sputum) can also be processed and used for MTB and Rif diagnosis using Truenat. The processing of various extra-pulmonary samples is described below.

Reagents required:

Trueprep AUTO MTB Sample Pre-treatment Pack for sample processing

• Reagents stable for two years (2-40°C) or one month (temperatures up to 45°C)
• Avoid exposure to light or elevated temperatures
• Do not freeze

Steps in processing of non-sputum samples