TB Flashcards
How does the pathogen Mycobacterium tuberculosis primarily enter the body during a TB infection?
Answer:
Mycobacterium tuberculosis primarily enters the body through inhalation, as it is an airborne pathogen that makes its way into the respiratory tract and bronchial system.
What happens when macrophages encounter Mycobacterium tuberculosis?
Answer:
* When macrophages encounter Mycobacterium tuberculosis, they engulf the pathogen through phagocytosis and attempt to put it into a phagosome.
- However, tuberculosis can inhibit the phagolysosome, preventing the breakdown of the pathogen.
- As a result, the Mycobacterium multiplies within multiple macrophages.
Which cytokines are released by macrophages during a TB infection, and what is their effect?
Answer:
* Macrophages release cytokines such as
1. IL-1,
2. . IL-6,
3. . TNF-α during a TB infection.
- These cytokines attract more macrophages and lymphocytes to the area, leading to the formation of caseating granulomas.
Describe the formation of a caseating granuloma during primary TB infection.
Answer:
* The caseating granuloma usually forms within the right middle and lower lobe due to exposure to Mycobacterium tuberculosis.
- The pathogen multiplies within macrophages, leading to the release of cytokines and attracting more macrophages and lymphocytes.
- This immune response results in the formation of a caseating granuloma with central necrosis, surrounded by more macrophages and T lymphocytes.
What is the Ghon complex, and what causes its formation during primary tuberculosis?
Answer:
- The Ghon complex is a combination of a Ghon focus (caseating granuloma) forming in the middle or lower lobe, close to the pleura, and hilar lymphadenopathy granuloma forming in a nearby lymph node.
- It occurs as a result of the body’s attempt to wall off and protect against the spread of Mycobacterium tuberculosis.
What role do T cells play in the immune response to tuberculosis?
Answer:
* T cells release IFN-γ (Interferon-gamma) during a TB infection.
- IFN-γ stimulates more macrophages to come to the area and form granulomas, as well as recruit additional macrophages and T cells to help contain and control the Mycobacterium infection.
Why is the detection of IFN-γ important for TB diagnostics?
Answer:
- The detection of IFN-γ is important for TB diagnostics because it is a key immune response marker specific to Mycobacterium tuberculosis infection.
- Measuring IFN-γ levels can aid in diagnosing TB and differentiating it from other respiratory conditions.
What is the primary risk factor for a patient to develop primary TB with a Ghon complex?
Answer:
- exposure to Mycobacterium tuberculosis.
- They must come into contact with the bacterium to contract the infection.
Name some patient populations at a higher risk of exposure to tuberculosis.
Answer :
- Prisoners
- Healthcare workers
- . Homeless individuals
- Immigrants coming from regions with a high prevalence of TB
- Intravenous (IV) drug abusers
What does exposure to TB mean for individuals at risk?
Answer:
* means that individuals are at risk of acquiring the infection.
- However, exposure alone does not guarantee the development of active TB disease.
- Some individuals may clear the pathogen or enter a latent phase, while others may progress to active TB over time.
What happens after a patient acquires primary TB infection?
Answer:
they may enter a latent phase or develop primary progressive tuberculosis.
- Latent Phase: This occurs in over 90% of cases, during which the immune system contains the infection, and the individual does not show any symptoms. However, the bacteria remain dormant and can reactivate later, leading to secondary tuberculosis.
- Primary Progressive Tuberculosis: This occurs in less than 10% of cases, where the disease continues to worsen, causing more damage to the lung tissue.
- It’s important to note that not all individuals exposed to TB will progress to active disease; many may remain asymptomatic or control the infection in a latent state.
What happens to the Ghon complex in most cases of latent TB, and how does the immune system respond to the infection in these cases?
Answer:
* In over 90% of cases of latent TB, the Ghon complex undergoes fibrocalcification, resulting in a Ranke complex.
- The immune system effectively walls off the tuberculosis, keeping it in a dormant, shut-down state.
- Fibrocalcification and immune control prevent the bacteria from multiplying, dividing, destroying lung tissues, and causing symptoms.
How does immunosuppression impact latent TB, and what patient populations are at high risk of reactivation or progression to active TB?
Answer:
Immunocompromised individuals, such as those with HIV, post-transplant patients, those on immunosuppressive medications, individuals with diabetes mellitus and chronic kidney disease, alcoholics, malnourished individuals, and elderly patients, are at high risk of reactivation or progression of latent TB.
- Immunosuppression weakens the immune system’s ability to keep the pathogen dormant, allowing it to replicate, grow, and spread to other areas, leading to active TB.
What are the characteristics of secondary (reactivation) TB, and how does it differ from primary TB?
Answer:
- Secondary (reactivation) TB occurs when the latent TB pathogen, previously kept dormant, is reactivated due to a temporary period of immune system depression.
- The bacteria start to multiply and grow, moving upward from the Ghon complex to the upper lobes of the lungs.
- This reactivation causes fibrocaseous necrosis and consolidation in the upper lungs, resulting in fibrocavitary lesions.
How can you differentiate between primary TB and reactivation (secondary) TB based on the affected lung lobes?
Answer:
- In primary TB, the Ghon complex typically affects the lower and middle lobes of the lungs.
- In contrast, in reactivation (secondary) TB, the infection progresses from the latent phase to the upper lobes of the lungs, resulting in fibrocaseous necrosis and fibrocavitary lesions in the upper lungs.
What is primary progressive TB, and what patient populations are at a higher risk for developing this form of TB?
Answer:
Primary progressive TB is a form of tuberculosis where the immune system is not strong enough to contain and keep the infection dormant after the initial exposure.
Patients with certain risk factors, such as HIV infection, post-transplant status, immunosuppressive medications, diabetes mellitus, chronic kidney disease, alcoholism, malnourishment, and elderly patients, are at higher risk of developing primary progressive TB.
How do primary progressive TB and secondary reactivation TB present clinically, and why do they appear similar?
Answer: P
rimary progressive TB and secondary reactivation TB have similar clinical presentations.
- In both cases, the infection progresses to the upper lobes of the lungs, causing fibrocavitary lesions.
The difference lies in the underlying mechanism:
- in primary progressive TB, the immune system is initially unable to contain the infection, whereas in
- secondary reactivation TB, the infection is reactivated due to temporary immune system depression.
Which pulmonary complications can occur in patients with TB, particularly in cases of fibrocaseous lesions, consolidations, Ghon complex, and hilar lymphadenopathy?
Answer:
Patients with TB, particularly those with fibrocaseous lesions, consolidations, Ghon complex, and hilar lymphadenopathy, can experience the following pulmonary complications:
- Pneumothorax: Fibrocavitary lesions in the upper lobe may extend into the parenchyma and pleura, leading to air leakage into the pleural cavity.
- Bronchopneumonia: Fibrocaseous necrosis may impede the clearance of pathogens, leading to the development of bronchopneumonia.
- Pleural effusion (TB pleurisy): Inflammatory cytokines released from the Ghon complex can cause increased capillary permeability and fluid leakage, leading to pleural effusion.
- Hemoptysis: Fibrocavitary lesions can erode bronchial blood vessels, leading to coughing up blood (hemoptysis).
- Productive cough: Compression of nearby bronchial systems by fibrocavitary lesions can cause inflammation and trigger a productive cough.
- Fever: Cytokines released from granuloma and fibrocaseous necrosis, such as IL-1, IL-6, and TNF-α, affect the hypothalamus, leading to fever, night sweats, and weight loss.
How do symptoms differ between primary TB, secondary TB, and asymptomatic cases?
Answer:
Often, primary TB patients, and sometimes secondary TB patients, may be asymptomatic. However, when symptoms are present:
- Primary TB: Symptoms may include fever, productive cough, and lymphadenopathy (hilar lymphadenopathy).
- Secondary TB: Symptoms are similar to primary TB, with additional features like hemoptysis due to fibrocavitary lesions.
- Asymptomatic cases: These cases show no noticeable symptoms and are often detected through routine screening or contact tracing.
hat are the features of pulmonary tuberculosis, whether it’s secondary reactivation TB or primary progressive TB?
Answer:
- hemoptysis,
- productive cough,
- fever,
- night sweats, and
- weight loss.
What are the complications associated with tuberculosis?
Answer:
pneumothorax,
bronchopneumonia, and
pleural effusion.
What clinical signs should you look for when suspecting tuberculosis?
Answer:
look for symptoms like hemoptysis, productive cough, fever, night sweats, and weight loss.
What is the typical presentation of primary TB?
Answer: Often, primary TB is completely asymptomatic, showing no noticeable symptoms.
What are the characteristics of extrapulmonary tuberculosis, specifically systemic miliary TB?
Answer:
Extrapulmonary tuberculosis, specifically systemic miliary TB, occurs when TB spreads to other organs through the bloodstream, causing disease in multiple areas of the body.
What are the signs and symptoms of TB meningitis?
Answer:
headache, focal neural deficits, nausea, vomiting, and photophobia.
What is scrofula (cervical lymphadenitis) associated with tuberculosis?
Answer: Scrofula is characterized by swelling of the cervical lymph nodes and is a manifestation of tuberculosis.
What is constrictive pericarditis, and how is it related to tuberculosis?
Answer:
Constrictive pericarditis occurs when the pericardium of the heart becomes fibrotic and calcified.
It can be associated with tuberculosis.
What are the clinical manifestations of hepatitis caused by tuberculosis?
Answer:
- Hepatitis caused by tuberculosis leads to liver injury and an increase in AST and ALT levels in the blood.
- Symptoms include abdominal pain (right upper quadrant), hepatomegaly, and elevated liver function tests (LFTs).
What is sterile pyuria, and how is it related to TB?
Answer:
* Sterile pyuria occurs when TB infiltrates the kidney, causing an increase in white blood cells in the urine.
- TB is not detected in urine cultures in such cases.
