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What is the gram stain and shape of Mycobacterium tuberculosis?
- Gr+, technically Acid Fast
- Rods
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True/False: HIV a major risk factor for TB?
True
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True/false: Mycobacteria is one of the agent that leads to chronic pneumonia
True
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True/false: Mycoplasma is one of the agents that leads to chronic pneumonia
False; its mycobacteria
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What are three major risk factors for mycobacteria infection?
- Alcoholics
- Homeless
- HIV positive/ immunocompromised
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What is the source for M. tuberculosis?
Human reservoir
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What is the mode of transmission for M. tuberculosis?
Respiratory droplets
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True/False: M tuberculosis has a human reservoir
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True/False: M. avium has a human reservoir
False; soil and water is where they are found
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True/False: M intracellulare has a human reservoir
False; soil and water is where they are found
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What is the transmission method for M. avium?
Inhalation, ingestion
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What is the transmission method for M. intracellulare?
Inhalation ingestion
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True/False: M intracellulare is transmitted person-to-person
False; it is transmitted through inhalation and ingestion
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True/false: M. avium is transmitted through respiratory droplets
False; it is transmitted through inhalation and ingestion
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What are the most common pathogens of TB in HIV in the US?
- M. avium
- M. intracellulare
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Can M avium and M. intracellulare be transmitted person-to-person
Nope. They are both inhaled or ingested
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True/False: M tuberculosis is fast-growing
False; they are slow growing
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What is M tuberculosis oxygen need?
Aerobic
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True/false: M tuberculosis is somewhat acid fast, like Nocardia
False; M tuberculosis is strongly rapid fast
- What type of staining method is used for M tuberculosis
- Acid fast
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Is M tuberculosis an endospore former?
No
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True/False: M tuberculosis is an endospore former
False; they are non endospore former
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Why does not M tuberculosis stain well?
- Hydrophobic wall
- Mycolic acid and lipoarabinomannan
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What is the composition of Mycobacterium cell wall?
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True/False: Mycobacterium’s lipid barrier is hydrophilic
False; lipid implies hydrophobic, so duh
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Mycobacterium has clumping ability due to which factor?
Cord factor
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True/False: Mycobacterium is susceptible to UV, heat
True
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What is the name of the special stain used for Mycobacteria?
Ziehl-Neelsen acid fast stain
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What color would non acid-fast organism stain under Ziehl-Neelsen stain?
Blue
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What color does M. tuberculosis stain in Ziehl-Neelsen acid-fast stain?
Pink
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What is the name of the fluorescent dye used to stain M. tuberculosis?
Auramine O
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What is Auramin O?
A more sensitive fluorescent dye for Mycobacterium
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What is the medium that M. tuberculosis grows on?
Lowenstein-Jensen medium
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True/False: M tuberculosis can grow on blood agar
False; Lowenstein-Jensen medium
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What makes Lowenstein-Jensen a good medium for M. tuberculosis?
Enriched, selective, has lots of glycerol
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True/False: M tuberculosis survives and replicates in activated macrophages
False; they survive and replicate in unactivated macrophages
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Where do M tuberculosis survive and replicate?
Unactivated macrophages
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Do M. tuberculosis elicit granulomas?
Yes, allows it to survive in the host indefinitely
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What are the conditions that lead M tuberculosis to become dormant?
- Limited nutrients
- Immune response
- Low oxygen
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What are the conditions that allow M tuberculosis to become active?
- Nutrients
- Compromised immunity
- Oxygen
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True/false: dormant M tuberculosis has thickened cell wall
True
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For M tuberculosis to become dormant, there must be _____ amount oxygen, and nutrient source ____, and host immune system is _____.
low; limited; responding
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For M tuberculosis to go from dormant to active, oxygen source is ____, host immune is _____ and there are ____amount of nutrient
Available; compromised; abundant
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True/false: M tuberculosis appears as a red rod in gram-stained specimens
Fals
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True/false: after being stained with carbolfuchsin, M tuberculosis resists decolorization with acid-alcohol
True
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True/false: M tuberculosis has a large amount of mycolic acid in its cell wall
True
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True/false: M tuberculosis appears as a red rod in acid-fast stained specimen
True
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What is the component of M tuberculosis that forms serpentine-like colonies on Lowenstein-Jensen agar?
Cord factor
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What is a tubercle?
Granuloma
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What causes the formation of granulomas?
Cell-mediated immune response led to granuloma formation
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What are epithelioid cells?
Chronically activated macrophages
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What composes multinucleate giant cells?
Fused epithelioid cells
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Can M tuberculosis be transmitted through closer personal contact?
Yes
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Can M tuberculosis be transmitted via endotracheal intubation?
Yes
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True/False: all individuals with TB are infectious
False; only TB of lungs or larynx are infectious
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True/False: All TB, active and latent, are infectious
False; latent is noninfectious
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Is latent TB infectious?
Nope
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True/False: we are easily infected by TB but our immune system is mostly resistant to them
Yes, phagocytosed by alveolar macrophages, or large particles get trapped in mucus and removed by respiratory cilia
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True/False: 90% of infected will never develop a clinical disease
True
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Once M Tuberculosis is inhaled, what are the three possible?
- Immediate clearance by our immune system
- Latent infection
- Immediate onset = primary disease
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What is Ghon complex?
Pulmonary granuloma and calcified fibrotic hilar/ mediastinal lymph nodes
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True/False: Ghon complex is seen on Xrays for latent TB infection
False; it is seen in primary TB
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What is Primary TB?
Active TB disease
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What is military TB>
Hematogenous dissemnination to any body site
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Where are most granulomas seen with reactivation TB?
At the apex because TB is aerobic
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True/false: miliary TB can occur during primary or reactivation to any tissue or organ
True
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What are symptoms of primary pulmonary TB?
- Fever
- Pleuritic or substernal chest pain
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What are sympstoms of reactivation pulmonary TB?
- Cough
- Weight loss
- Fatigue
- Fevers
- Night sweats
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What could be seen on chest xray for reactivation TB?
- Nodular and linear areas of interstitial pulmonary opacification predominately in upper lobes
- Cavitation
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What can be found on cxr in primary pulmonary TB?
Ghon complex
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What is the gold standard for diagnosing TB?
Culture on Lowenstein-Jansen
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