TB 1 Flashcards
what organism causes tuberculosis
mycobacterium tuberculosis
what is meant by latent TB disease
infected but asymptomatic; disease is not active
what makes something considered multidrug resistant TB
TB resistant to at least 2 preferred anti-TB drugs
what countries are at high risk for TB
mexico philipines Vietnam india china
what age is most commonly affected by TB
25-44
what are the risk factors for TB
- age: 25-44
- low SES
- non-caucasion
- prolonged contact with infected
- HIV (most important risk factor)
what are the caracteristics of mycobacterium tuberculosis?
gram positive aerobic with unusual waxy coating
what immune system response is essential to controlling M. tuberculosis infections
T-lymphocytes
what are the primary T cells involved in immune response to TB
CD4+ (a type of T-lymphocyte)
what are the 3 factors that contribute to TB disease progression
- amount of M. TB organisms inhaled
- virulence of the organisms
- host’s cell-mediated immune response
if someone has latent disease, will they test positive on skin test? how long can they remain latent
yes, will test positive
may be latent for the rest of there lives
how does active infection occur from a latent infection
immune system fails to wall off infection during the primary infection
when is the highest risk of going from latent to active
2 years after infection
what are the 4 screening guidelines for TB screening
- emigration within 5 years from high prevalence countries
- Immunosuppressed patients
- close contacts of people with active TB
- those with evidence of recent TB infection
what are 4 downfalls of PPD skin test
- booster effect
- prior BCG vaccination can mess up results
- requires multiple visits to conduct test
- subjective interpretation
PPD measures presence of cellular immunity by assessing what
delayed-type hypersensitivity
what blood test can be done for TB
quantiferon gold (gold standard) T-SPOT
what do blood tests for TB look for
interferon-gamma release
what are 4 advantages to blood tests for TB over skin tests
- provides quick and specific results
- no booster effect
- prior BCG does not effect results
- lab based assay - unbiased interpretation
