Fouty- Mycobacteria and TB Flashcards
acid fast stain for mycobacteria
Ziehl-Neelsen
India, China, Africa, Indonesia
highest rate of TB
slow growing
waxy outer coat
acid fast
aerobic bacilli
mycobacterium
part of cell wall structure that is stained with Z-N stain
Mycolic acid
mycobacteria infection in HIV patients consists of what
MAC (M.avium)
slow growing
non-pigmented
MTB complex
develop slowly and elicit a granulomatous response
Mycobacterial infection
Mycobacteria infection elicits what 2 host responses
delayed type hypersensitivity
cell-mediated immunity
host response with non-activated macrophages
delayed type hypersensitivity
host response with activated macrophages
cell-mediated immunity
human host only
most common cause of mycobacterial infection
M. tuberculosis
can be transmitted to humans by milk; basis of MTB vaccine
M. bovis
spread from person to person by aerosol
M. tuberculosis
has evolved to evade innate immune response (escapes to replicate in cytoplasm through non-activated alveolar macrophages)
M. tuberculosis
Infects tissue monocytes; widespread inflammation; get into lymph nodes and disseminate to other parts of the body
MTB
in most cases, activation of ____ immune response eventually controls initial MTB infection
adaptive
control of TB is mostly a _____ immune response
adaptive (Th1)
____ release IFNgamma that activate infected macrophages and help them kill TB bacilli
Th1 cell
_____ immune response leads to formation of granulomas that controls initial infection but rarely totally clears all infection
adaptive
Most common cause of calcified granuloma in the US
Histoplasmosis
Most common cause of calcified granuloma in the world
TB
aka calcified granuloma, indicates site of primary infection
Ghon Focus
calcified granuloma + Ipsilateral lymph node calcification
Ranke Complex
Immediate clearance of inhaled MTB bacilli without activating adaptive response
no TB infection
Uncontrolled Primary infection
Primary infection (active disease) seen in who
in children and immunocompromised
Delayed control of infection after induction of adaptive immune response:
latent infection
bilateral hilar adenopathy
HIV, children, immunocompromised
primary TB infection
2 outcomes with latent TB infections
lifelong dormancy
reactivation
reactivation of latent disease usually w=in what lobes of lung
upper lobes
_____ disease is most contagious (due to reactivation of latent disease)
cavitary disease
miliary tuberculosis (hematogenous spread)
Initially infection was controlled in granuloma; then the immune response dropped for whatever reason; bacilli broke through and disseminated into blood stream
miliary TB
due to drop in immunity
cough and night sweats
most commonly in lungs
MTB reactivation
In people co-infected with M. tuberculosis and HIV the rate they will develop tuberculosis is ____% per year.
10%
diagnose latent TB infection
TB skin test
IFN-gamma assay
diagnose active TB
positive culture
NAAT
_____ staining can indicate presence of Mycobacterium but cannot discriminate between species
Zieh-Neelsen
Rx active TB
Begin with 2 months of Isoniazid, ethambutol, pyrazinamide, rifampin
Followed by 4-6 months of isoniazid and rifampin
how to treat active TB
watch patient take the medicine everyday
inhibits mycolic acid synthesis; give with pyridoxine (vitamin B6)
Isoniazid (INH)
inhibits RNA polymerase
SE: orange colored body fluids
induces CYP450 enzymes
Rifampin
____ + oral contraceptive = baby
Rifampin
inhibits transferases of cell wall
SE: retrobulbar neuritis
CI in children too young to notice vision problems
Ethambutol
disrupts cell membrane metabolism and transport
Pyrazinamide (PZA)
MTB drug resistance that causes problems
resistant to INH and Rifampin
found in soil and water
mycobacterial disease in HIV patients
inhaled or swallowed
M. avium complex (MAC)
most common mycobacterial disease in AIDS patients in the US
MAC
Recommended treatment regimen: clarithromycin or azithromycin combined with ethambutol and rifampin
MAC
Slowly evolving cavitary disease that resembles tuberculosis on chest radiography
MAC pulmonary disease
observed in elderly, female non-smokers
chronic cough, shortness of breath, fatigue and other less specific symptoms
lingular or middle lobe infiltrates with a patchy, nodular appearance on radiography and associated bronchiectasis (chronically dilated bronchi)
Lady Windermere syndrome (MAC pulmonary disease)
formation of a solitary pulmonary nodule
MAC pulmonary disease
can sometimes clear on its own
+ PPD test may result from this infection
M. kansasii
____ and ____ are critical in controlling TB infection
Th1 CD4 cells and INF gamma
main risk factor for TB
immunocompromised
main thing to remember to treat TB
multiple drugs for a prolonged period of time
