At the central level (Level III), testing that requires highly advanced skills, infrastructure and biosafety precautions is offered. An important expectation at this level is to provide testing to resolve discordant results, troubleshooting, training support to other levels, QA and monitoring, and surveillance.
- FL-LPA, SL-LPA and targeted NGS tests are all applicable at this level. The moderate complexity automated NAATs with high throughput could also be considered at this level. In addition, the class of high complexity reverse hybridization NAAT for PZA is suited to this level and can make use of existing LPA infrastructure.
- Culture and phenotypic DST using solid or liquid media should be available at this level. At a minimum, phenotypic DST for the new and repurposed drugs should be available.
- Establishing capacity for sequencing (targeted or WGS) is becoming increasingly important. Targeted NGS tests are high complexity tests in their current format and are most suitable for centralized laboratories equipped with specialized skills and infrastructure (including information technology [IT] and data storage).
Fig. 3.1. Organization of a TB diagnostic network
