Development, Stability Testing, and Performance of Xpert MTB/RIF Proficiency Testing Material in National Tuberculosis Reference Laboratory, Nairobi City County, Kenya
| dc.contributor.author | Nganga, Margaret Wairimu | |
| dc.date.accessioned | 2024-09-26T12:26:22Z | |
| dc.date.available | 2024-09-26T12:26:22Z | |
| dc.date.issued | 2024-01 | |
| dc.description | A Research Thesis Submitted in Fulfilment of the Requirements for the Award of the Degree of Master of Science in Infectious Diseases (Clinical Bacteriology) in the School of Health Sciences of Kenyatta University, January 2024. Supervisors 1. Abednego Musyoki 2. Nelson Menza | |
| dc.description.abstract | Systematic and ongoing proficiency testing (PT) program is a fundamental element of external quality assurance in diagnosis of TB using Xpert MTB/RIF assay. In many resource-limited setting, particularly in Kenya, PT is poorly covered and largely inconsistent following inadequate supply of dried tube specimens (DTS). This has serious negative implications on patients‘ management and TB control programs. The aim of this study was to develop, assess stability and performance of local DTS panels for Xpert MTB/RIF assay PT in Kenya. This study was conducted at the National Tuberculosis Reference Laboratory (NTRL) and DTS piloting was done in Xpert MTB/RIF sites in Nairobi City County. An experimental study design was adopted to develop and assess stability DTS panels, and a cross sectional study design was adopted to pilot panels. The piloting sites were purposively selected to include all the twenty (20) TB diagnostic laboratories that were using Xpert machine in Nairobi City County, from August 2019 to December 2019.Bacterial strains stored in a -80oC freezer at the NTRL were retrieved and processed following standard bacteriological procedures. The strains were sub-cultured in liquid culture media (MGIT), growth detected by the BACTEC® MGIT 960® system, and their purity confirmed. Bacterial cultures were then heat-inactivated and pre-tested using Xpert MTB/RIF assay before preparing DTS. To assess the effect of drying on the stability of DTS panels, DTS panels were left uncapped inside a biosafety cabinet for 7, 10, and 14 days, and immediately subjected to Xpert MTB/RIF assay. In assessing the stability of the DTS panels at various temperatures as anticipated in TB diagnostic laboratories that use Xpert machine across the Kenya, 36 DTS panels from 7, 10, and 14 days drying periods were held at 18oC, 20oC, 24oC, 33oC, and 40oC for 12 weeks, and subjected to Xpert MTB/RIF weekly. For piloting, a set of 5DTS panels, 5 disposable sterile dispensing pipettes, processing instructions, and PT results evaluation form were delivered to the targeted piloting sites in a sealable transparent bag for testing by the Xpert MTB/RIF personnel who printed the results, entered them into the reporting form, and a scanned image send to the principal investigator for analysis. Data were analyzed using STATA v17 and variables were summed up in medians, interquartile range, means, and standard deviation (SD). Each of the five pilot DTS panels was assigned an accuracy score of 20 points, and individual laboratory scores as follows; incorrect determination of either MTB detection (0 points), unsuccessful result (error, invalid, or no results) (5 points), RIF-indeterminate result (10 points), and correct determination of both MTB detection and RIF resistance (20 points). Total scores for each laboratory were computed, with 100% being considered Excellent, ≥80% Satisfactory, and <80% Unsatisfactory. The DTS panels‘ probe A Ct values were within the expected mean range (16-23) and SD limit (≤3), with100% concordance between those dried for 7, 10 or 14 days and the pretest results. Except for DTS panels held at -80oC, the probe A mean Ct values of panels dried for 7 and 14 days increased with increasing temperature (from -20oC to 40oC) during the 12 weeks‘ study period (p= <0.001), with the greatest mean Ct value increment was at 40ᵒC.Ninety-five per cent (18/20) of piloted laboratories reported the expected, with 10% (2/20) of sites giving discordant results, false MTB detection (5%, 1/20) and error (code 5007) (5%, 1/20). 90% (18/20) of the piloted sites had satisfactory, 80% had excellent, and 10% (2/20) had unsatisfactory results. This study recommends adoption of 7-day DTS drying period, -80oC and 40oC storage up to 2 weeks, and up scaling DTS production for profic | |
| dc.description.sponsorship | Kenyatta University | |
| dc.identifier.uri | https://ir-library.ku.ac.ke/handle/123456789/28904 | |
| dc.language.iso | en | |
| dc.publisher | Kenyatta University | |
| dc.title | Development, Stability Testing, and Performance of Xpert MTB/RIF Proficiency Testing Material in National Tuberculosis Reference Laboratory, Nairobi City County, Kenya | |
| dc.type | Thesis |