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  1. Structure
    • Strict aerobe
    • special media for growth
    • 3-6 weeks for colony growth
    • Killed by pasteurization, UV light
    • High mycolic acid content
    • Many protein, polysaccharide Ag
  2. Epidemiology
    • Inhalation of bacteria
    • Also ingesteion of infected milk
    • Long, prolonged exposures
    • Sensitive to UV light
    • One third of population infected, 30 million have active disease, 2-3 million deaths
    • Drug resistance
  3. Primary infection: pathogenesis
    • Response to initial infection
    • Bacteria deposited in well ventilated lower middle lobes
    • Engulfed by alveoloar macrophages
    • Leads to granuloma-> some bacteria can be transmitted to hilar lymph nodes
    • May disseminate
    • Lesions usually heal by fibrosis
    • Can remain viable for long periods of time in well ventilated areas
  4. Reactivation: pathogenesis
    • Areas of high O2 tension and low lymph drainage
    • Lesions have casseous necrosis and multiple bacilli
    • Can lead to bronchial cavitation bronchial spread
  5. Immunity
    • High innate immune reactions
    • 10% of immunocompetant people who are infected with convert to disease
    • DTH and CMI develop after infection, control infection
    • Acquired immunity is mostly cell mediated, but humoral does help
  6. Primary TB: manifestations
    • Asymptomatic or fever and malaise
    • Mid zone infiltrate of the lungs on x-ray
    • Ghon complex=calcifed lymph nodes
    • 5% -> active miliary TB
  7. Reactivation: clinical manifestation
    • 10% recovering from primary infection
    • Usually after 50 in men
    • Immunosuppresion, malnutrition, alcoholism, diabetes, old age, etc...
    • Cough, dry
    • Fever, malaise, fatigue, sweath, and weight loss
    • Infiltrates in apices of lungs coalesce to form cavities and destroys lung tissue
  8. Diagnosis
    • PPD: positive test means infected at sometime: positive test means not infected or anergic due to AIDS, immunosuppresive drugs
    • Lab: acid fast smears; culture (special culture); susceptibility testing important; quantieron gold test
  9. Treatment
    • Isoniazid, ethambutol, rifampin, pyrazinamide, streptomycin, combination
    • Continous treatment with 2-3 drugs for 6 months reduces probability of mutation
    • DOT
    • 2 weeks of therapy usually ends infectivity
  10. Prevention
    • Isozianid prophylaxis in high risk cases
    • BCG vaccine
Card Set:
2011-11-15 03:20:26

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