Tuberculosis
Features and Clinical Management of Tuberculosis
Epidemiology
Oldest recognized infection in humans
Can survive in a harsh environment for years
TB outbreaks: associated with socioeconomic disturbance
Break in the decline of TB: Why? HIV
Disease of inner-cities and minority: white – endemic, Blacks and hispanics: children (marker of undiagnosed uncontrolled adult disease) and 30-40
Pathogenesis
Infected respiratory droplet nuclei (3 nuclei is all it takes)
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inhaled
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eliminated or implanted
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exudative pneumonia
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lymphatics (lung)
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lymphohematogenous spread
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extrapulmonary disease
4-6 weeks: delayed type hypersensitivity
Granuloma formation is hallmark of disease
Granuloma
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caseation
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inspissation
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calcification
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liquefaction
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cavity
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closure or spread (contiguous or bronchial)
Treatment: must close cavity or you are dead!
Risk Factors: breathing
Presentation:
Fatigue, anorexia, weight loss, low grade fevers (over weeks to months), cough which gradually progresses over weeks to months. Mucopurulent sputum production.
Drenching night sweats, profound weight loss: indicative of far-advanced disease
Must get an HIV antibody if someone is diagnosed with TB
CXR: infiltrates seen in apical and posterior segments, cavitation is common
Diagnostic methods:
TB screen: delayed type hypersensitivity,
sputum examination (gold standard): demonstration of acid-facst bacilli (AFB) with Ziehl-Neelsen of fluorochrome stain
Individual without high risk background: more likely to have a false positive on TB screen
Treatment
: 3 principles
(1) regimens must contain multiple drugs
(2) must be taken regularly
(3) must continue for sufficient time
Drug susceptible TB
Short course: Isoniazid (INH), rifampin (RMP), pyrazinamide (PZA), streptomycin (SM) for 2 months then INH, rifampin for 4 months: 4x2 then 2x4
Standard: INH, RMP for 9 months
INH-resistant
Short course: RMP, ethambutol (EMB), PZA, SM for 2 months, Then RMP, EMB, PZA for 4 months
Standard: RMP, EMP for 12-18 months
Preventative treatment
: >35 toxicity equals risk of infection look for high risk factor x immunocompromising conditions, contact, converted within 2 years (reactivation)
TB and HIV
TB is an early complicatoin of HIV infection
Presentation: atypical presentation is typical: no hypersensitivity reaction, extrapulmonary manifestations common, generalized lymphadenopathy
the earlier the presentation: worse the prognosis
CXR: normal chest x-ray