Mycobacterium Flashcards
mycobacterium tuberculosis bacteriology
long, skinny, straight or curved complex structure- stained with acid fast bacilli slow growing obligate aerobe facultative intracellular
mycobacterium tuberculosis virulence factors
complex cell wall intracellular- hides from immune system siderophores chromosomal mutations inhibition of phagosome-lysosome fusion
complex cell wall of TB does
resists phagocytosis
impermeable- disinfectant and antibiotic resistance
resists drying
what proteins prevent phagosome-lysosome fusion
ESAT-6
CFP-10
3 forms of TB
primary
secondary
disseminated, extrapulmonary
Ghon complex
calcified caseous granuloma filled with bacteria
immune response
CD4 cells activated and release INFgamma nd TNF alpha which activate macrophages
macrophages release cytokines (TNF, IL1, IL6, IL8) that lead to inflammation
cells in a granuloma
macrophages
fibroblasts
lymphocytes
neutrophils
marker of latent TB
Ghon complex
secondary TB
reactivation of bacteria in Ghon complex in immunosuppressed states OR re-infection by exogenous bacteria
sites of dissemination of TB
lymph nodes kidneys bones genital tract brain anywhere
symptoms of active TB
fever weight loss night sweats cough bloody sputum fatigue decreased appetite
diagnosis of active TB
abnormal CXR
positive PPD
acid fast bacilli from sputum sample
culture
TB is commonly with
HIV
active TB treatment
rifampin isoniazid pyrazinamide ethambutol/streptomycin 6-24 months
diagnosis of latent TB
PPD- intrepretation depends on risk factors
5mm positive if
HIV infected close contact with infectious case CXR consistent with prior untreated TB organ transplants immunosuppressed
10mm
clinical conditions that make them high risk
kids
15mm
no known risk factors
treatment of latent
chemoprophylaxis with 1 or 2 drugs
BCG vaccine
avirulent strain that is missing ESAT-6 and CFP-10
used in endemic countries
prevents it in kids
doesn’t stop reactivation of latent infections
mycobacterium avium complex
major cause of death in AIDS patients
in dirt and water
MAC colonoizes
GI tract or respoiratry tract and then spreads
MAC symptoms`
diarrhea
fatigue
fever
wasting
m fortuitum
opportunistic pathogen
widely in environment
skin lesions, abscesses
M leprae
causes leprosy- chronic, progressive disease of skin and nerves
m leprae grows in
armadillos
schwann cells
macrophages
tuberculoid description
less severe
Th1
lepromatous description
severe
TH2
sensory nerve damage –> injury and secondary infection
diagnosis leprosy
microscopic exam
history
symptoms- numbness, loss of temp sensitivity
leprocy tuberculoid treatment
dapsone
rifampin
lepromatous treatment
dapsone
rifampin
clofazimine
