Micro: TB Flashcards
Component of Mycobacterium tuberculosis cell wall that is stained.
Mycolic acid
acid fast stain
Virulence factor for TB
Chord Factor
What are the 3 types of tuberculosis?
- Primary: initial infection
- Secondary: reactivation of initial infection
- Miliary: disseminated to multiple organ systems
Describe the pathogenesis of TB.
- TB enters the lung tissue
- alveolar macrophages engulf TB but it survives
- TB multiplies within macrophages further attracting more macrophages to the site to infect
- Granuloma forms with a center of necrosis (casesating)
- Granuloma remains dormant for years until a stimulus reactivates it
Describe the changes in Tubercles (granulomas) during a TB infection over time.
Caseous lesion: cheese-like
Ghon Complex: lungs and lymph node infected
-calcified caseous lesion
Tuberous cavities: tubercle that liquefies and forms air-filled cavity
What are the steps for Dx of TB?
Step 1: PPD test (type IV hypersensitivity)
Step 2: if step one is (+) then do a CXR
Which agar plate can diagnose TB?
Lowenstein-Jensen agar
What is Tx for a patient diagnosed with TB?
4 drugs in combination (RIPE) 1. Rifampin 2. Isoniazid 3. Pyrazinamide 4. Ethambutol (done for 6 months total)
Tx for people exposed to TB infected pts.
Isoniazid
Treatment program for pts infected with multi-drug resistant (MDR) TB or XDR-TB.
DOTS: Directly Observed Treatment Short course
Who is at risk for developing Mycobacterium avium complex (MAC) pneumonia?
IC
Chronic lung disease
Primary MAC pneumonia is similar to TB pneumonia. Who is at risk of developing secondary or disseminated MAC pneumonia?
AIDS pts with T cell count below 50 cells/ml
Tx for MAC pneumonia
1. Clarithromycin or Azithromycin \+ 2. Ethambutol \+ 3. Rifampin
Prophylaxis for AIDS pts to prevent MAC infection
Clarithromycin or Azithromycin
Weakly acid fast gram (+) aerobe with branching filament pattern.
Nocardia sp.
