Flashcards in Chapter 15: Respiratory Infections 3 Deck (28):
Type of pneumonia caused by a mycobacterium that is transmitted through airborne droplets and is highly contagious.
What bacteria causes tuberculosis?
Why is mycobacterium tuberculosis so resistant to destruction?
They have a capsule composed of waxes and fatty substances that protect them
True or false: Tuberculosis prompts a typical acute inflammatory reaction.
False; it prompts a cell-mediated response
How does the immunes system respond to a tuberculosis infection?
1) Macrophages phagocytose the bacteria, but can't destroy them, so they carry them to other parts of the lung and regional lymph nodes.
2) A cell-mediated response develops after several weeks (lymphocytes and plasma B cells appear)
3) Lymphocytes attract and activate macrophages, allowing them to ingest and destroy the bacteria.
4) The macrophages fuse into giant cells and form granuloma nodules that still contain some viable bacteria.
True or false; Most of the symptoms of tuberculosis are caused by the initial infection.
False; most of the symptoms are caused by reactivation of the latent TB in granulomas, resulting in secondary (cavitary) progressive pulmonary TB.
Inactive lesions caused by TB infection arrest by granulomas in the lungs and lymph nodes that heal with scarring and often calcify.
What do granuloma nodules contain?
Clusters of monocytes and giant cells, central areas of necrosis (caseous), and a rim of fibrous tissue.
A form of cell death in which the tissue maintains a cheese-like appearance
How is TB diagnosed?
1) Skin test (Mantoux): positive can indicate previous exposure or active infection (hypersensitivity to TB proteins)
2) Chest xray (granulomas appear as pulmonary infiltrate)
3) Sputum culture
Treatment of TB
Abx or chemotherapeutic agents
True or false: Most cases of TB infection result in secondary progressive pulmonary TB.
False; most TB infections never cause any symptoms
What can lead to a primary TB infection becoming progressive primary TB?
1) Large # of organisms infect
2) Host immune system is compromised
When can someone with TB infect others?
When they have active TB (a tuberculosis cavity in the lungs); then they discharge lots of bacteria in sputum
What is the most common cause of active TB?
Reactivation of an old TB infection
How does active TB spread to other parts of the body?
Through lymph or blood
Type of TB in which organisms are carried in lymphatics
from lung infection to regional lymph nodes and then
systemically throughout body, forming multiple small
nodular TB granuloma foci in many organs (including lungs); very serious
TB may develop in distant
sites/organs due to hematogenous spread from a lung
TB focus; secondary focus of infection may progress
even if pulmonary TB site did not (was a healed
infection/granuloma and no symptoms of pulmonary
TB); also serious
What results in drug resistant TB?
Failure to complete treatment
TB caused by organisms resistant to at least 2 anti-TB drugs
MDR-TB (Multiple drug-resistant TB)
Caused by organisms no longer controlled by many or all antiTB
drugs; “super resistant”; WHO carefully monitors, controls
XDR-TB (Extremely drug-resistant TB)
An inflammation of the tracheobronchial mucosa
Type of bronchitis common in URIs; raw, sore throat, cough
Type of bronchitis that is secondary to constant irritation of the respiratory mucosa by smoking or pollution
Condition in which bronchial walls become weakened by severe inflammation and become permanently dilated, flaccid, saclike, and fusiform
True or false: Bronchiectasis is sometimes secondary to other conditions.
False; it is always secondary to other conditions
How is bronchioectasis diagnosed?
Bronchogram or CT scan