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17 Cards in this Set

  • Front
  • Back
What can cause a false positive PPD?
Bacillus calmette Guerin(BCG) vaccine, prior treated tbc(once exposed, the PPD remains positive even after treatment, exposure to nontbc mycobacteria.
How is M. tbc cultured?
In C(14) labeled palmitic acid broth with growth detected by release of CO2. Samples can also be cultured on Lowenstein-Jensen agar, but results take weeks.
How is tbc transmitted?
Inhalation of infected respiratory droplets.
What is primary tbc?
An infection in the lungs of a previously unexposed individual.
Describe the pathogenesis of primary tbc?
Mycobacteria ingested by phagocytes trigger cell mediated immunity leading to caseating granulomas.
What is the result of most primary infections with tbc?
No symptoms(asymptomatic 90% positive PPD, Ghon complex
What groups are at risk for symptomatic primary tbc?
Those with deficient cell mediated immunity(children, elderly, immunocompromised or immunosuppressed).
What is the pathology of symptomatic primary tbc?
In the lungs and other organs, large caseous granulomas develop and eventually, liquefy, creating cavitary lesions with air filled levels(air fluid levels in lungs only)
What is a Ghon complex?
Ghon complex=Ghon focus(calcified nodule in the middle or lower lung)+ a calcified hilar lymph node.
What is secondary tbc?
Reactivation of a prior infection infection due to weakened immunity(months to years later). Most adult cases of active tbc are secondary.
What are the signs and symptoms of active pulmonary tbc?
Cough with hemoptysis, low grade fever, night sweats and weight loss. Chest X ray showing upper lobe infiltrates, cavitary lesions, calcifications.
What is the treatment for active tbc?
6 months regimen: initially 4 drugs(rifampin, isoniazid, pyrazinamide, ethambutol) for 2 months, followed by 4 months of isoniazid and rifampin. Multiple drugs should always be used to prevent the emergence of multidrug resistant strains.
What percentage of primary infections progress to active tbc?
5% of those primarily infected will develop reactivation tbc in the first 1-2 years. Another 5 % will develop reactivation sometime later in life.
Normal infected individuals have a 10% lifetime risk of active infection, while immunocompromised patients are at higher risk.
What is miliary tbc?
Disseminated infection leading to millet seed sized granulomas in lungs, liver spleen, bone, kidneys, spine and other organs.
Who gets miliary tbc?
Those with weakened cell mediated immunity(HIV positive, elderly and children).
What is Pott's disease?
Tbc infection of the thoracic/lumbar spine leading to destruction of intervertebral discs/bodies and compression fractures.
What is the most common extrapulmonary manifestation of tbc?
Scrofula or cervical mycobacterial lymphadenitis.