FA Mycobacteria Flashcards
PPD + means
current infection, past exposure, or BCG vaccinated
PPD - means
no infection or anergic (steroids, malnutrition, immunocompromise) and in sarcoidosis
What is a more specific test (have fewer false positives from BCG vaccine) than PPD for TB?
Interferon-gamma release assay (IGRA)
histology of TB
Caseating granuloma - central necrosis with multinucleate Langerhans giant cell
Infection with TB in a non immune host (usually child) –>
primary tuberculosis
primary TB is characterized by
Ghon complex = hilar nodes + Ghon focus (usually in mid zone of lung)
If primary TB heals by fibrosis –>
immunity and hypersensitivity –> Tuberculin +
If primary TB –> prorgressive lung disease (usu in HIV or malnutrition) –>
death (rare)
if primary TB –> military TB –>
death
if primary TB –> re allergic lymphatic or hematagenous dissemination –>
dominant tubercle bacille in several organs –> reactivation in adult live
Infection with TB in a partially immune hyper sensitized host (usually adult) –>
secondary TB (reinfection)
secondary TB presents as a
fibrocaseous cavitary lesion usually in upper lobes
what are the six places where extra pulmonary TB tends to present?
CNS (parenchymal TB or meningitis) Vertebral body (Pott dz) Lymphadenitis Renal GI Adrenals
What are the four big TB symptoms
- Fever
- Night sweats
- Weight loss
- Hemoptysis
What disease causes pulmonary TB like symptoms?
M Kansasii
What disease causes disseminated non-TB disease in AIDS and is often resistant to multiple drugs?
M avium-intracellulare
What is the treatment for M avium-intracellulare?
prophylactic treatment with azisthromycin
what virulence factor in mycobacteria inhibits macrophage maturation and induces release of TNF-apha?
cord factor
what does cord factor of TB do?
inhibits macrophage maturation and induces release of TNF-alpha
What part of mycobacteria inhibits phagolysosomal fusion?
Sulfatides (surface glycolipids)
What do sulfatides in TB do?
inhibit phagolysosomal fusion
An acid-fast bacillus that likes cool temperatures (infects skin and superficial nerves –>
“glove and stocking” loss of sensation) and cannot be grown in vitro
Mycobacterium leprae
What is the leprosy reservoir in the US?
Armadillos
What are the two forms of leprosy/Hansen?
- Lepromatous
2. Tuberculoid
Presents diffusely over the skin with leonine facies and is communicable; characterized by low cell-mediated immunity with a humoral Th2 response
Lepromatous Hansen
limited to a few hypoesthetic, hairless skin plaques; characterized by high -cell mediated immunity with a largely Th1-type immune response
Tuberculoid Hansen
Immune response to lepromatous hansen?
low cell-mediated immunity with a humoral Th2 response
immune response to tuberculoid hansen?
high -cell mediated immunity with a largely Th1-type immune response
treatment for tuberculoid form of hansen?
multi drug therapy of damson and rifampin for 6 months
treatment for lepromatous form of hansen>
dapsone + rifampin + clofazimine for 2-5 years
describe the leonine facies of leprosy
loss of eyebrows, nasal collapse, lumpy earlobe
