22/07/2025
GeneXpert Test for Tuberculosis (TB)
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1. Objective:
The objective of the GeneXpert test was to detect the presence of Mycobacterium tuberculosis (MTB) DNA and rifampicin resistance in clinical samples (e.g., sputum), using automated real-time PCR.
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2. Principle:
The GeneXpert test was based on nucleic acid amplification (real-time PCR). The system amplified MTB DNA and simultaneously detected mutations in the rpoB gene region associated with rifampicin resistance. The process was fully automated within a closed cartridge to reduce contamination.
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3. Materials:
• GeneXpert machine
• GeneXpert MTB/RIF cartridge
• Sample reagent (buffer)
• Sputum sample (or other clinical specimen)
• Vortex mixer
• PPE (gloves, lab coat, mask)
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4. Procedure:
1. A fresh sputum sample was collected in a sterile container.
2. Sample reagent was added in a 2:1 ratio to the sputum and shaken for 10–15 minutes.
3. The treated sample was transferred into the GeneXpert cartridge.
4. The cartridge was loaded into the GeneXpert machine.
5. The machine automatically performed DNA extraction, amplification, and detection.
6. Results were displayed on the screen within ~2 hours.
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5. Result:
• MTB Detected / Rifampicin Resistance Detected
• MTB Detected / Rifampicin Resistance Not Detected
• MTB Not Detected
• Invalid / Error / No Result (if issues occurred)
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6. Uses:
• It was used for rapid diagnosis of pulmonary and extrapulmonary TB.
• It detected rifampicin resistance, indicating possible multidrug-resistant TB (MDR-TB).
• It guided early treatment decisions in suspected TB patients.