Application of Home Validated Panel Dna Materials for Proficiency Testing of Who Endorsed Molecular Assays: Mtbdrplus and Xpert Mtb/Rif Assay
Creators: name: Dagne, Zekarias
Publisher: name: National Academic Digital Repository of Ethiopia
Year: 2016

description: Background: Tuberculosis (TB) is a major public health problem in Ethiopia. Laboratory plays an important role in the diagnosis of TB and its treatment monitoring. Quality assured molecular drug susceptibility assay is an essential for rapid detection of MDR-TB cases and early treatment initiation Proficiency testing is one of the EQA methods in evaluating the quality service delivery however, it was not widely applied for molecular assays in Ethiopia mainly due to the inadequate capacity of preparing PT DNA panels' in-country. Objective: The aim of this study was to assess Application of Homemade and validated panel DNA Materials for Proficiency Testing of the WHO endorsed Molecular Assays (GenoType® MTBDRplus and Xpert MTB/RIF assays) in TB Culture and DST laboratories, and in selected GeneXpert sites of Ethiopia. Methods: A cross sectional study was conducted in five regional reference laboratories and two specialized hospital TB culture and DST laboratories which have molecular GenoType® MTBDRplus assay of Ethiopia, and in eight selected health facilities with Xpert MTB/RIF testing sites in Addis Ababa during the period between July 2015 and January 2016. PT DNA materials were validated at EPHI, NTRL and distributed to MTBDRplus and Xpert MTB/RIF testing facilities. All data from participating laboratories were captured and analyzed using SPSS version 20. A total of 194 (130 for MTBDRplus and 64 Xpert MTB/RIF) DNA panels were distributed to regional reference and hospital TB laboratories. Test results agreement between the participant laboratories and reference were estimated using Kappa statistics. The sensitivity, specificity, predictive value susceptible, predictive value resistance, accuracy and reproducibility of participant laboratories were calculated against the reference lab. Results: 130 panel samples with a combination of 65 (50%) spiked sputum and 65 (50%) extracted DNA were tested in seven Regional Reference Laboratories which have MTBDRplus assay. Almost all, 129 (99.2 %) were correctly reported to the Isoniazid and Rifampicin susceptibility. Sixty nine (53.1%) reported isolates were resistance to both INH and RIF (MDR), 41 (31.5%) susceptible to both INH and RIF, and 19 (14.6%) INH susceptible but RIF resistance strains correctly reported with respect to the reference result. There was 100% agreement in detecting MDR and resistance to any of the two drugs (INH and RIF) (kappa = 1) but the agreement was 97.8% for the detection of susceptible strains (Kappa = 0.9). Among 64 spiked sputum strains (32 M. tuberculosis DNA with no RIF resistance and 32 M. tuberculosis DNA with RIF resistance (probe E Mutant detected ) distributed to GeneXpert sites, all of them were correctly reported. Overall agreement on detection of M. tuberculosis and RIF susceptibility was 100 % (Kappa =1.0). Conclusion: There was an excellent agreement between the participant laboratories and the reference laboratory for the detection M. tuberculosis and drug susceptibility using MTBDRplus and Xpert MTB/RIF assays. Therefore, we can apply home validated PT DNA panels as one of the EQA methods for WHO endorsed molecular assays MTBDRplus, whereas in the Xpert MTB/RIF assay a large scale validation is important to use as Panel test since, the sites we used for this study in Addis Ababa, are small compared to the general population in Ethiopian context.