Lower RT Infections Part 2 Flashcards
Donut sign
Calcification below the hilum of the lungs on a lateral X ray
From lymphadenopathy
2 main diseases caused by mycobacteria
TB
Leprosy
When are non-tuberculosis mycobacteria a problem?
In weakened hosts
3 properties of TB infection
Slowly replicating
Strictly aerobic
Unique cell wall composition
How long is pulmonary TB treatment usually for?
6 months minimun
Where in the lungs is TB usually found
Apex
Cavities
Because it is strictly aerobic
How is TB transmitted?
Airborne (aerosolized)
Droplet nuclei containing tubercle bacilli are inhaled, enter lungs, and travel to alveoli
What cell type is responsible for granuloma formation?
Macrophages
Classic pathologic finding in TB disease
Caseating granuloma
Primary TB disease
Primary infection consists of a small parenchymal focus that spreads via local lymphatics to regional lymph nodes
Often results in occult, subclinical bacteremia that seeds distant sites
Younger age = higher risk
Mantoux Tuberculin Skin Test
Intradermal injection of TB antigen
Positive result (feel a bump) indicates TB infection
Doesn’t distinguish latency from active disease
Read 48-72 hours after given
Based on Type 4 hypersensitivity (delayed-type)
3 reasons for false positive Tb test
Infection with non-TB mycobacteria
Previous BCG vaccination
Incorrect method of TST administration
5 reasons for false negatives for TB test
Cutaneous anergy (no immune response - PID or HIV) Recent TB infection (2 months) Very young age Recent-live virus vaccination Overwhelming Tb disease
Infection vs Disease
Infection depends on exposure history
Risk of disease depends on patient factors
2 main classes of viruses that cause resp infections
Double-stranded DNA
Single-stranded (-)sense RNA
