Supporting National TB Reference Laboratories and surveys in Africa – Supra-National TB Reference Laboratory

The CTB has recently been successfully evaluated for its reference laboratory potential, resulting in it being awarded the responsibility to function as the 3rd Supra-National Reference Laboratory of the WHO on the African continent. As part of this function, it provides technical support to two national reference laboratories in Africa, namely those in Malawi and Namibia. Progressive missions to improve quality management systems for laboratory testing, as well as programme initiatives towards TB surveillance activities, have been performed in these countries. In addition, the Centre provided reference laboratory support to the Malawi Prevalence Survey and the Namibia Drug Resistance Survey for both quality assurance and second-line DST. An expanded approach, aiming to assess the proficiency of nine of the 22 highest burden TB national reference laboratories in Africa on culture identification and DST, has been recently initiated through WHO-AFRO. Although the performance of countries in the first round was sub-optimal for several countries, feedback and further provision of quality-related support has resulted in an overall improvement in the quality of results generated by these laboratories. These developments have been important and have shown the great value of the support functions conducted by CTB.

Extended DST testing

Extended DST testing offered includes drugs such as rifabutin, linezolid, clofazamine and bedaquiline using agar, MGIT960 system as well as the microdilution broth method for selected drugs.  Additionally, high-level isoniazid is tested as well as multiple fluoroquinolones, which include ofloxacin, moxifloxacin, levofloxacin and gatifloxacin.  MIC testing is also performed for all drug classes.
   Broth Microdilution MIC testing – Extended Drugs

Next-Generation Sequencing for drug resistance determination

The Centre for Tuberculosis has developed in-house capacity to perform Next-Generation Sequencing and bioinformatics.  The approach includes whole genome sequencing performed using Illumina technology.  A bioinformatics workflow solution has been established, which is capable of predicting susceptibility using published genetic resistance determinants.  Further developments on employing this methodology are currently being developed as a tool for phylogenetic analysis.  As of the first quarter of 2016, approximately 3000 genomes have been sequenced.

Next-Generation Sequencing Workflow