Tuberculosis Antibodies Rapid Test Cassette

Intended Use

The Tuberculosis Rapid Test Cassette is a lateral flow immunoassay designed for the qualitative detection of antibodies to Mycobacterium tuberculosis (including M. bovis and M. africanum) in human whole blood, serum, or plasma, facilitating the diagnosis of tuberculosis (TB).

Summary

Tuberculosis (TB) is primarily transmitted through airborne particles expelled by coughing, sneezing, and talking, with poorly ventilated areas posing the highest risk of infection. TB is a significant global health concern, accounting for 8 million new  cases and  3 million deaths annually. Timely diagnosis is essential for controlling TB, enabling early treatment and preventing further transmission. Traditional diagnostic methods include skin tests, sputum smear, sputum culture, and chest X-rays; however, these methods can be time-consuming, require specialised laboratory equipment, and may be cost-prohibitive, particularly in developing countries.

Serological methods provide a promising alternative for TB diagnosis, as they are simpler, more affordable, and relatively non-invasive. The Tuberculosis Rapid Test Cassette detects anti-TB antibodies (all isotypes: IgG, IgM, IgA, etc.) in human samples, utilising a combination of recombinant antigens to identify elevated levels of these antibodies.

Principle

The Tuberculosis Rapid Test Cassette functions as a qualitative membrane strip-based immunoassay:

  1. Test Procedure:
    • Recombinant tuberculosis antigens are immobilized in the test line region of the cassette.
    • A specimen (whole blood, serum, or plasma) is applied to the specimen well, where it reacts with the antigen-coated particles.
    • This mixture migrates along the test strip and interacts with the immobilized tuberculosis antigens.
    • The appearance of a colored line in the test region indicates a positive result if anti-TB antibodies are present.

Warnings and Precautions

  • For in vitro diagnostic use only.
  • Intended for healthcare professionals at point-of-care sites.
  • Do not use after the expiration date.
  • Read all information in the leaflet before performing the test.
  • Store the test cassette in its sealed pouch until use.
  • Handle all specimens as potentially hazardous.

Composition

  • Test Components:
    • Membrane strip coated with Tuberculosis antigens in the test line.
    • Rabbit anti-Tuberculosis antibody in the control line.
    • Dye pad containing colloidal gold coupled with Tuberculosis antigens.
  • Materials Provided:
    • Package insert
    • Dropper
  • Materials Required But Not Provided:
    • Specimen collection container

Storage and Stability

  • Store in the sealed pouch at 4-30°C (40-86°F).
  • Stable until the expiration date printed on the label.
  • Use opened test kits within one hour.
  • Avoid prolonged exposure to heat and humidity.

Specimen Collection and Handling

  • Suitable for testing whole blood, serum, or plasma.
  • Follow standard clinical laboratory procedures for specimen collection.
  • Separate serum or plasma from blood as soon as possible to avoid hemolysis; only clear non-hemolyzed specimens should be used.
  • Store specimens at 2-8°C (36-46°F) for up to 7 days or freeze at -20°C (-4°F) for longer storage (do not freeze whole blood specimens).

Test Procedure

  1. Allow the test device and specimens to equilibrate to 15-30°C (59-86°F).
  2. Remove the test cassette from the sealed pouch.
  3. Place the test cassette on a clean, level surface.
  4. For serum or plasma: Transfer 3 drops (approximately 100 µL) to the specimen well (S) and start the timer.
  5. For whole blood: Transfer 1 drop (approximately 35 µL) to the specimen well (S), add 2 drops of buffer (approximately 70 µL), and start the timer.
  6. Wait for results to appear, reading at 15 minutes. Do not interpret after 20 minutes.

Interpretation of Results

Positive

Two lines appear: one in the control region (C) and another in the test region (T).

Negative

One line appears in the control region (C); no line in the test region (T).

Invalid

No line appears in the control region (C); review procedure and repeat the test.

Quality Control

The test includes an internal procedural control. A colored line in the control region (C) confirms sufficient specimen volume and proper technique. Positive and negative controls should be tested periodically for quality assurance.

Limitations

  • The Tuberculosis Rapid Test Cassette is for in vitro diagnostic use only, intended for detecting anti-TB antibodies in human specimens.
  • It should not be used as the sole criterion for diagnosing TB.
  • All results must be interpreted alongside other clinical information. If negative results occur with persistent clinical symptoms, additional testing is recommended.

Performance Characteristics

  • Clinical Sensitivity: 98.90%
  •  Clinical specificity: 99.30%
  • Cross-Reactivity: No significant interference was observed with common infectious disease specimens or endogenous substances.

Bibliography

  1. Laszlo, A. (1999). Tuberculosis: laboratory aspects of diagnosis. CMAJ, 160, 1725-1729.
  2. Bothamley, G.H. (1995). Serological diagnosis of tuberculosis. Eur. Resp. J., 8, 676s-688s.