External Quality Assurance for CBNAAT

PT is an important component of EQA for Cartridge-based Nucleic Acid Test (CBNAAT) under the National TB Elimination Programme (NTEP) and guarantees accurate and reproducible results.

Importance of EQA/ PT for CBNAAT

• Gives assurance to users that the instrument is functioning properly.
• Checks to verify that users can correctly interpret and report results.
• Verifies that there are no major errors in the process control system and that samples are identified, tested and reported correctly.
• Helps to recognise major problems with an instrument or user and take remedial action.

Process of EQA for CBNAAT

1. EQA of CBNAAT is done using dried tube panels consisting of Mycobacterium tuberculosis (MTB) strains that are RIF resistant/ sensitive/ Non-tuberculous Mycobacteria (NTM)/ negative.
2. Coordination of the EQA activity, manufacture and validation of the panels is undertaken by the National TB Institute, Bangalore.
3. The process of manufacturing and validating the Dried Tube Specimen (DTS) for EQA panels involves:
   
   • Culturing the mycobacterial strain in the liquid culture system followed by inactivation of the cultures using sample reagents
   • Further incubating for 84 days for confirmation of inactivation followed by preparation of DTS panel cultures and their validation.
4. Once validated, the DTS panels are dispatched to the CBNAAT sites.

Each CBNAAT site receives a set of 5 tubes/ machine.

EQA/ PT for CBNAAT is done once in a year/ machine/ per site.

Based on the performance of the CBNAAT laboratory, corrective actions are taken by the supervising authority such as Intermediate Reference Laboratory (IRL)/ National Reference Laboratory (NRL). During the on-site visits by the IRL and the NRL, quality indicators for CBNAAT are evaluated and corrective actions are suggested.