TB Flashcards
what prevented TB eradication?
AIDS
describe the difficulty of diagnosing mycobacteria? how is it circumvented?
gram stain poorly and are slow growing.
acid fast staining
how is acid fast staining performed?
carbolfuchsin stain, then acid/alcohol decolorization and methylene blue counterstain
acid fast hold carbolfuchsin stain during decolorization
how is TB caught and where does it infect?
inhalation
goes to lymph nodes, kidney, bones, CNS by hematogenous spread and GI by swallowing infected sputum
what is the result of TB infection in an immunocompetent host?
raises CMI response and holds infection latent for decades. may reactivate
how does TB spread hematogenously?
intracellular infection of naieve macrophages (activated ones clear it)
how do CD 8 cells respond to TB? what else is important for containment?
CD8 cells kill infected macrophages and establish caseating granulomas to contain the infection
TNF alpha important for containment
what is classic pulmonary TB?
cough, weight loss, fever, night sweats, hemoptysis and chest pain
how is pulmonary TB diagnosed?
sputum culture/biopsy and chest X ray
how are scrofula, GU, CNS, skeletal, GI, and miliary presentations of TB diagnosed?
scrofula (lymph node)-fine needle aspirate, GU-IV urography and urine culture, CNS- MRI and spinal tap, skeletal-MRI and joint fluid culture, GI- x ray and CT of abdomen, miliary- chest xray with bright spotlight, lateral xray or chest CT
how are pediatric TB cases handled?
trace source, culture from gastric lavage. watch for miliary and meningial disease
what is one difficulty of TB treatment?
antibiotic resistence
takes 2 weeks to culture and 3 weeks for resitance testing
how is TB treated?
with directly observed therapy with at least 4 drugs featuring isoniazid- isolate pt for first 2 weeks
what vaccine exists for TB? where is it used? how is it implicated in diagnosis?
BCG (bovine) vaccine used abroad- not cost effective here
may create false positive PPD
what are the most helpful factors for reducing the incidence of TB in a population?
good diet and housing to boost CMI
latent cases are not contagious
