DISORDERS OF THE RESPIRATORY SYSTEM PART 3.3 (based on T) Flashcards
What is the global ranking of TB as a cause of death?
TB is the 13th leading cause of death worldwide and the second leading infectious killer after COVID-19.
How many people were estimated to have TB worldwide in 2021?
10.6 million people.
What is the estimated number of men, women, and children affected by TB in 2021?
6 million men, 3.4 million women, and 1.2 million children.
How many people died from TB in 2021?
1.6 million people.
Why is multidrug-resistant TB (MDR-TB) a public health crisis?
Because it remains a health security threat and only about 1 in 3 people with MDR-TB accessed treatment in 2021.
What is the ranking of the Philippines in terms of TB cases worldwide?
The Philippines ranks 4th worldwide in TB cases.
How many Filipinos have active TB?
About 1 million Filipinos.
How many Filipinos die from TB daily?
Nearly 70 Filipinos die every day from TB.
What is the morphology of Mycobacterium tuberculosis?
(ANSS)
Aerobic,
nonmotile, and
slightly curved or straight bacilli.
What staining method is used to identify Mycobacterium tuberculosis?
Ziehl-Neelsen method (acid-fast staining).
What component in the cell wall of Mycobacterium tuberculosis makes it unique?
Mycolic acid, a long fatty acid that gives the bacterium its characteristic resistance.
What are the two classifications of mycobacteria?
M. tuberculosis complex and
Non-tuberculous mycobacteria (MOTT).
What are the members of the Mycobacterium tuberculosis complex?
(TBAM)
M. tuberculosis,
M. bovis,
M. africanum, and
M. microti.
What is the primary mode of transmission of TB?
Airborne transmission through inhalation of infectious droplets from a person with pulmonary or laryngeal TB.
How many infectious droplets can a single cough or talking for 5 minutes produce?
3,000 infectious droplets.
What is a rare mode of TB transmission?
Ingestion of contaminated unpasteurized dairy products from infected cattle or skin inoculation from an abrasion.
Why are fomites not considered important in TB transmission?
TB is not transmitted through contaminated objects, so special handling of utensils and bed linens is unnecessary.
Who are the most common sources of TB infection in children?
Infectious adolescents or adults, usually household contacts.
Why is TB transmission from children under 10 years old uncommon?
Most children cannot expectorate sputum, and their sputum has a lower bacilli load than adults.
What is the risk of untreated childhood TB infection?
It can remain dormant and reactivate as adult pulmonary TB.
What factors influence the risk of TB infection in child contacts?
Proximity and duration of contact, degree of lung involvement, and sputum smear positivity of the index case.
Why is the first week of TB treatment critical for adults?
Adults remain contagious until two weeks after starting anti-TB drugs.
Which age group is at the highest risk for disseminated TB disease?
Children under four years old and infants with TB infection.
What percentage of untreated latent TB infections progress to active TB?
5-10%.
What factors increase the risk of TB infection?
Close contact with an infectious TB patient, overcrowding, and institutional settings like hospitals, prisons, and shelters.
What factors influence the progression of TB infection to active disease?
Age, time after exposure, nutritional status, intercurrent diseases, immunosuppression, and lifestyle factors.
What medical conditions increase the risk of TB reactivation?
HIV/AIDS, diabetes mellitus, silicosis, severe kidney disease, low body weight, organ transplants, and immunosuppressive treatments.
What are the effects of chemotherapy on TB transmission?
Success or failure in treatment adherence impacts the spread and control of TB.
What are common environmental factors that increase TB transmission risk?
Overcrowding and poor ventilation.
How is TB transmitted and what is the portal of entry?
Through inhalation of infectious droplet nuclei, which are deposited in the alveoli.
How many bacilli are generally required for successful TB infection?
Approximately 5-200 inhaled bacilli.
What is the incubation period of TB?
3 weeks to 3 months, but can be shorter with a large inoculum.
What is the first stage of TB pulmonary pathology?
Scavenging by non-activated alveolar macrophages that ingest the tubercle bacillus.
What is the second stage of TB pulmonary pathology?
Symbiosis stage where macrophages fail to destroy bacilli, leading to uncontrolled replication.
What happens in the third stage of TB pathology?
Cell-mediated immunity develops, inhibiting the logarithmic increase in bacilli.
What are the two possible outcomes in the fourth stage of TB pathology?
4A: Weak immunity leads to widespread dissemination;
4B: Strong immunity leads to stabilization or regression of the tubercle.
What characterizes the fifth stage of TB pathology?
Caseous liquefaction, extracellular bacillary growth, cavity formation, and bronchial dissemination.
What is the primary lung lesion in primary TB called?
Ghon focus.
Where is the Ghon focus typically located?
Subpleural area of the upper segment of the lower lobe or lower segment of the upper lobe.
What is the Ghon complex?
A combination of the primary pulmonary focus, infected lymph nodes, and associated lymphangitis.
What is the significance of lymphohematogenous spread in TB?
It is usually asymptomatic but can cause extrapulmonary lesions years later.
What are the different clinical forms of tuberculosis (TB)?
TB can be pulmonary or extrapulmonary, including TB of the pancreas, bones, and other organs.
What is latent TB infection?
Latent TB infection is asymptomatic, with the only clue being a positive tuberculin skin test (PPD).
How is PPD (tuberculin skin test) administered?
PPD is done intradermally.
What are the characteristics of latent TB?
Infection associated with tuberculin hypersensitivity and a positive tuberculin test, but no clinical or radiographic manifestations.
What is the primary disease form of intrathoracic TB?
It occurs mostly in infants, with a higher risk of disease progression until age 5, and is also referred to as Primary TB.
What is progressive primary TB disease?
A complication where the primary pulmonary focus enlarges, develops a caseous center, and leads to pneumonia, persistent cough, fever, malaise, and weight loss.
What are common radiographic findings in primary TB?
Primary complex: primary focus, lymphangitis, and regional lymphadenitis, with or without pleural effusion.
What is the significance of pleural effusion in TB?
Pleural effusion may be part of the Ghon complex or a complication of primary TB.
What is endobronchial tuberculosis?
TB involving the bronchi due to peribronchial lymph node enlargement or direct nodal extension, leading to airway obstruction.
What are potential complications of endobronchial TB?
Asphyxia, obstructive emphysema, atelectasis, and lobar hyperaeration.
What symptoms are associated with endobronchial TB?
Moderate fever, anorexia, night sweats, weight loss, paroxysmal cough, cyanosis, and expiratory wheezes.
What is pericardial TB?
TB involving the pericardium, often due to direct invasion or lymphatic spread from caseous subcarinal nodes.
What are the clinical signs of pericardial TB?
Low-grade fever, anorexia, poor weight gain, chest pain, pericardial friction rub, distant heart sounds, tachycardia, and narrow pulse pressure.
What are the diagnostic findings for pericardial TB?
CXR: Cardiomegaly; ECG: Low QRS amplitude, ST segment and T wave abnormalities; Pericardial fluid: Sanguinous with lymphocytic reaction.
What is chronic pulmonary TB?
A more common form in adolescents with prior TB infection, presenting as chronic cough, fever, chest pain, and hemoptysis.
What is miliary TB?
A generalized hematogenous TB with massive bloodstream invasion, often occurring within 3-6 months post-infection, primarily affecting infants and young children.
What are the clinical features of miliary TB?
High fever, dyspnea, cough, prostration, and symptoms from systemic organ involvement.
What is the characteristic radiographic finding in miliary TB?
Chest X-ray shows millet seed-like densities over the lung fields.
What is tuberculoma?
A rounded lesion that develops as a residual of parenchymal TB, often containing caseous or granulomatous tissue with fibrous encapsulation and sometimes calcification.
Why is tuberculoma often confused with malignancy?
Because it appears as a solid mass-like lesion on imaging.
