Podcast
Questions and Answers
Acid Fast Bacillus (AFB) can only be stained by a simple stain.
Acid Fast Bacillus (AFB) can only be stained by a simple stain.
False
M.tuberculosis is positive for the Niacin test.
M.tuberculosis is positive for the Niacin test.
True
M.kansasii is part of the Mycobacterium avium complex.
M.kansasii is part of the Mycobacterium avium complex.
False
7H11, 7H12, and 7H10 are all types of solid culture media for Mycobacterium.
7H11, 7H12, and 7H10 are all types of solid culture media for Mycobacterium.
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The Ziehl Neelsen stain (Z-N) is less sensitive than the Auramine-Rhodamine stain (AR).
The Ziehl Neelsen stain (Z-N) is less sensitive than the Auramine-Rhodamine stain (AR).
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The Ziehl-Neelsen Stain is primarily used for the identification of active TB through direct microscopy of respiratory samples.
The Ziehl-Neelsen Stain is primarily used for the identification of active TB through direct microscopy of respiratory samples.
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Middlebrooks 7H12 culture media is used for the diagnosis of latent tuberculosis (LTBI) specifically.
Middlebrooks 7H12 culture media is used for the diagnosis of latent tuberculosis (LTBI) specifically.
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Miliary TB is categorized under the types of active tuberculosis disease.
Miliary TB is categorized under the types of active tuberculosis disease.
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The Tuberculin skin test (TST) does not require the administration of PPD for diagnosis.
The Tuberculin skin test (TST) does not require the administration of PPD for diagnosis.
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PCR (Polymerase Chain Reaction) is a method used exclusively in the culture process for diagnosing Tuberculosis.
PCR (Polymerase Chain Reaction) is a method used exclusively in the culture process for diagnosing Tuberculosis.
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Isoniazid is effective for treating latent tuberculosis in children for a duration of 9 months.
Isoniazid is effective for treating latent tuberculosis in children for a duration of 9 months.
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QuantiFERON-TB Gold test results can produce false positives due to BCG vaccination.
QuantiFERON-TB Gold test results can produce false positives due to BCG vaccination.
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A positive tuberculin skin test (TST) in adults is indicated by an induration of 5-10 mm.
A positive tuberculin skin test (TST) in adults is indicated by an induration of 5-10 mm.
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The QuantiFERON-TB Gold test requires a blood sample to be processed within 12 hours for accurate results.
The QuantiFERON-TB Gold test requires a blood sample to be processed within 12 hours for accurate results.
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Latent tuberculosis infection (LTBI) can be treated with Isoniazid for 8 months in HIV positive individuals.
Latent tuberculosis infection (LTBI) can be treated with Isoniazid for 8 months in HIV positive individuals.
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The standard treatment for latent tuberculosis infection (LTBI) in HIV positive patients is INH for 12 months.
The standard treatment for latent tuberculosis infection (LTBI) in HIV positive patients is INH for 12 months.
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Pregnant women with active TB are treated with INH, RIF, PZA, and EMB for a duration of 6 months.
Pregnant women with active TB are treated with INH, RIF, PZA, and EMB for a duration of 6 months.
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Children with latent TB infection should be treated with INH for 9 months.
Children with latent TB infection should be treated with INH for 9 months.
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The treatment regimen for active TB in HIV positive patients includes INH, RIF, PZA, and EMB for 6 months.
The treatment regimen for active TB in HIV positive patients includes INH, RIF, PZA, and EMB for 6 months.
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LTBI in pregnant women can be treated with INH for 6 months.
LTBI in pregnant women can be treated with INH for 6 months.
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The treatment of active TB in children includes INH, RIF, PZA, and EMB for a duration of 9 months.
The treatment of active TB in children includes INH, RIF, PZA, and EMB for a duration of 9 months.
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In HIV positive individuals, both active TB and LTBI are considered significant health concerns.
In HIV positive individuals, both active TB and LTBI are considered significant health concerns.
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The drug regimen INH for 9 months is used for treating LTBI in both HIV positive patients and pregnant women.
The drug regimen INH for 9 months is used for treating LTBI in both HIV positive patients and pregnant women.
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Study Notes
Mycobacterium Tuberculosis (MTB)
- Identification: AFB (Acid-Fast Bacilli)
- Staining: Not stained by simple or Gram stains, only by Ziehl-Neelsen (2.N) stain. Resistant to decolorization by acid or alcohol.
- Morphology: Rod-shaped, visualized with 2.N stain on a blue background or fluorochrome stains (Auramine-Rhodamine).
- Fluorescence Microscopy: Shows bacteria as orange-yellow in a black background (more sensitive than Z-N stain).
- Species: Includes MTB Complex (e.g., M. tuberculosis, M. bovis, M. africanum). Also includes NTM (Non-Tuberculous Mycobacteria) which are different species.
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Culture:
- Requires Löwenstein-Jensen medium (LJ medium).
- Egg-based media, 5-10% CO2.
- Slow-growing (long generation time).
- Colonies: Dry, irregular, off-white.
- Differentiating Tests (e.g., Middlebrook): Use enriched and selective broths/agar. These culture media have added nutrients and reagents.
- Biochemical Reactions: Niacin test, nitrate reductase, etc. Assess for these to help differentiate between species.
- Drug Susceptibility Testing (DST): Important for treatment. Done on solid media with antibiotic agents.
- Mycobacterial Cultures: Can be identified on solid media (Middlebrook's medium) within 2-4 weeks or less.
- MGIT (Mycobacteria Growth Indicator Tube): Radiometric assay, can quickly detect growth.
- Acid, Alkali, and Dryness Resistance: MTB shows resistance to them.
- Sensitivity to UV rays: Sensitive to UV.
Tuberculosis (TB)
- Transmission: Airborne.
- Primary Infection: Latent Tuberculosis Infection (LTBI) or Active TB disease.
- Disease Progression: Active disease results from reactivation of the infection or exogenous re-infection.
- Symptoms: Cough, fever, fatigue.
- Diagnosis: Tuberculin skin test (TST) to assess for LTBI. QuantiFERON-TB Gold In-Tube (QFT-GIT) assay useful.
Diagnosis of Active TB
- Specimen Collection: 3 sputum samples (morning preferred) are collected from patients with a deep, productive cough.
- Processing: The sputum undergoes decontamination, concentration, and centrifugation.
- Direct Detection: Acid-fast staining is used to analyze the sputum, confirming the presence of bacteria.
- Molecular Methods: Polymerase chain reaction (PCR) techniques are used to detect MTB DNA to confirm active infection.
- Biochemical Reactions: Used for confirmation or diagnosis.
- Culture: For confirmation, sputum is cultured on solid media (e.g., Middlebrook's).
Tuberculosis Pathology
- Spread: Lymphatic and/or hematogenous.
- Pathogenesis: Leads to inflammation and granuloma formation in affected tissues.
TB Diagnostics (cont.)
- TST (Tuberculin Skin Test): Purified protein derivative (PPD) injected intradermally, reaction assessed.
- QFT-GIT (QuantiFERON-TB Gold In-Tube): Blood test, measures interferon-gamma (IFN-γ) production in response to TB antigens.
- False-positive/negative results: Possible in both TST and QFT-GIT. Factors affecting the results should be known when interpreting the findings.
- Anergy: Inability to produce a positive skin test due to immune suppression (e.g., HIV infection, malnutrition).
TB Treatment
- Drug therapy: Multiple drugs are usually given for prolonged periods. Importance of adherence.
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Description
This quiz focuses on the identification and diagnosis of Mycobacterium species, including M.tuberculosis and M.kansasii. Test your knowledge on staining methods, culture media, and testing techniques for tuberculosis. Whether it's about the Ziehl Neelsen stain or the Tuberculin skin test, explore the crucial aspects of TB diagnosis.
