Flashcards in Pulmonary mycobacterial diseases Deck (35)
how are atypical or non TB mycobacteria infections classified?
rapid or slow growing mycobacteria
what are the rapid growing mycobacteria?
M. fortuitum complex
what are the slow growing mycobacteria?
MAC (avium, intracellulare)
progressive lung disease in non-TB pulmonary infections typically occurs in what type of patient?
underlying bronchiestasis or COPD
what are the two clinical forms of MAC? what are the demographics?
fibrocavitary - older male smokers with preexisting lung disease
fibronodular - nonsmoking women over 50 without underlying lung disease
what is the clinical presentation of non-TB mycobacterial infections?
usually typical or TB with cavitation 85-95%
what is required for diagnosis of non-TB mycobacteria?
sputum (2 positive cultures)
lung or tissue biopsy positive AFB smears
positive culture from pleural effusion fluid
what are the three possible consequences of TB contraction?
1. immediately cleared - no infection
2. primary TB - immediate onset of active disease
3. latent infection - possibility of reactivation
what % of the dormant population will develop a reactivation of TB infection?
what % of individuals who contract TB eventually devleop infection?
how does TB spread upon infection?
lymphatics - to regional lymph nodes
what is a Ghon complex on CXR?
unilateral lymphadenopathy suggestive of TB
what occurs if cell mediated immunity is inadequate? what is the result?
hematogenous dissemination - active disease and contagiousness
pulmonary symptoms occur in what % of cases of primary TB?
what are the radiographic findings of primary TB?
what type of TB infection is most common?
how is latent TB diagnosed?
evidence of cell mediated immune response to initial infection manifested by:
positive TB skin test (PPD Mantoux)
interferon gamma release assay (Quantiferon Gold)
how is the tuberculin skin test administered?
intradermal injection of 0.1 mL of purified protein derivative (PPD)
how are PPD tests analyzed?
mm induration of skin
NOT erythema perpendicular to long axis
what does a positive TB skin test mean?
documents infection but NOT active disease
what is associated with active TB infection / disease?
clinical and radiographic findings or disease
when does a skin test become positive? what does it document?
several weeks after infection
document a cellular immune response
what test is approved for screening for latent TB?
interferon gamma release assay
what is involved in the interferon gamma release assay?
T cell release of IFy following exposure to antigen specific to M. tuberculosis
can the interferon gamma release assay determine if infection is active or latent?
can the PPD skin test determine if infection is active or latent?
which TB test is NOT affected by BCG vaccination?
IFy release assay
what is the therapy for latent TB infection?
isoniazid 300 mg daily for 9 months
what drug is used for TB resistant to isoniazid?
what are the features of the fever associated with TB?
more marked as disease progresses and is classically diurnal
what are the general principles of TB therapy?
1. always use at least two drugs that have documented activity against the strain of TB
2. always use appropriate drug doses
3. the drug must be taken regularly
4. duration of therapy must be long enough for the circumstances
the initial phase of TB treatment requires how many drugs? for how long?
what is recommended for schedules that do not require daily doses?
the continuous phase of TB treatment requires how many drugs? for how long?
INH and RIF
additional 4-7 months