Related Experiment Video
Updated: Feb 12, 2026

Diagnosing Pulmonary Tuberculosis with the Xpert MTB/RIF Test
Published on: April 9, 2012
Unsuccessful Xpert® MTB/RIF results: the Nigerian experience
Abstract:
Setting: Nigeria, a high tuberculosis (TB) burden country. Objective: To study the rate, distribution and causes of unsuccessful Xpert® MTB/RIF test outcomes, with the aim of identifying key areas that need to be strengthened for optimal performance of the assay. Design: This was a retrospective analysis of data uploaded between January and December 2015 from Xpert facilities to the central server using GXAlert. Result: Of 52 219 test results uploaded from 176 Xpert machines, 22.5% were positive for Mycobacterium tuberculosis, 10.8% of which were rifampicin-resistant; 4.7% of the total number of results were invalid, 4.2% had error results and 2.1% no result outcomes. Technical errors were most frequent (69%); these were non-seasonal and occurred in all geopolitical regions and at all health facility levels. Temperature-related errors were more prevalent in the North-West Region, with peaks in April to June. Peak periods for temperature and machine malfunction errors coincided with the periods of low utilisation of the assay. Conclusion: The key challenge affecting performance was poor adherence to standard operating procedures. Periodic refresher training courses, regular supervision, preventive maintenance of Xpert machines and proper storage of cartridges are strategies that could improve Xpert performance.
Related Concept Videos
What is an Experiment?
Thomson's e/m Experiment
A particle with charge q, speed v, and mass m enters an area from the top, where the magnetic and electric fields are perpendicular both to the particle's motion and to one another. The magnetic...
Controls in Experiments
Randomized Experiments
Simple randomization
Simple...
Crossover Experiments
Crossover designs are performed even with smaller sample sizes since the samples can act as their controls. These are better than simple randomized trials since patients are exposed to all the treatments.
The Stanford Prison Experiment

