MENDEL-MANTOUX TEST
INDEX
1. Introduction
2. Procedure
3. Results
Introduction• Also known as the tuberculin
sensitivity test.• Screening tool for tuberculosis (TB)• Uses a Purified protein derivative (PPD)
tuberculin, a precipitate of glycerol molecules obtained from filtrates of sterilized and concentrated cultures of TB.
Procedure• A standard dose
consists of an intradermal injection of 0.1 ml solution for injection in the inner surface of the forearm
• Test is read 48 to 72 hours later.
• A person who has been exposed to the bacteria is expected to mount an immune response.
• The reaction is read by measuring the diameter of induration (palpable raised, hardened area) across the forearm in millimeters.
Erythema should not be measured
Results
Classification of reaction
Induration of 5 mm – 9 mm
• Persons with recent contacts with a TB patient
• Persons with nodular or fibrotic changes on chest X-ray consistent with old healed TB
• Patients with organ transplants, and other immunosuppressed patients
10 mm – 14 mm• Injection drug users• Residents and employees of high-risk congregate
settings (e.g., prisons, nursing homes, hospitals, homeless shelters, etc.)
• Persons with clinical conditions that place them at high risk (e.g., diabetes, prolonged corticosteroid therapy, leukemia, end-stage renal disease, chronic malabsorption syndromes, low body weight, etc.)
• Children less than four years of age, or children and adolescents exposed to adults in high-risk categories.
15 mm or more • Persons with no known risk factors for TB
False positive result
• Those who have received a BCG vaccine. Interpreted as latent TB infection.
• May be caused by a non-tuberculous mycobacteria.
• Another source of false positive results can be allergic reaction or hypersensitivity.
False negative result
• Infectious mononucleosis• Anergy • Live virus vaccine - The test should not be
carried out within 3 weeks of live virus vaccination.
• Sarcoidosis• Hodgkin's disease• Corticosteroid therapy/Steroid use• Malnutrition• Immunologically compromised
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