TB Flashcards
what is the strongest risk factor for developing active TB
- HIV
what appears to accelerate the progression of HIV disease?
- TB
MDR TB defined as resistant to which drugs?
- INH (isoniazid)
- RIF (rifampin)
XDR TB defined as
- MDR strain resistant to two classes of second line drugs
the BCG vaccine is which organism
- mycobacterium bovis
what kind of pathogen is mycobacterium tuberculosis
- facultative intracellular acid fast pathogen
MTB lives primarily where
- in macrophages
what kind of stain do you use for TB
- acid fast stain
what is the defining and unique feature of the mycobacterial cell wall
- mycolic acid
what does mycolic acid form
- myobacterial outer membrane
is there LPS in mycobacteria
- no LPS
MTB is transmitted by
- aerosols
how can MTB survive in macrophages?
- resistance reactive oxygen and reactive nitrogen species
- arrests phagosome maturation at a very early step
what kind of response leads to macrophage activation and MTB control?
what presents the antigen?
- TH1
- TB infected macrophages and dendritic cells
what are recruited to the site of infection in MTB control
- antigen specific CD4 and CD8 T cells
do antibodies play a role in MTB infection
- no
what happens after MTB infected macrophages are recognized by antigen specific CD4 and CD8 cell?
- cytokine production that activates macrophages to control MTB replication
which cytokine controls the TH1 response
what is it released by
what is the result of its release
- IL-12
- MTB infected macrophages
- leads to CD4 differentiation along TH1 path
what activates macrophages
what is it secreted by
what other chemical also helps to activate macrophages
- interferon gamma
- CD4 TH1 type T cells and CD8 T cells
- TNF-alpha
role of activated macrophages
- exhibit more efficient phagosome-lysosome fusion, reactive oxygen and nitrogen species
what do activated macrophages wall themselves into
- a granuloma
what is at the center of the granuloma
what composes the outside of the granuloma
- central region of macrophages, fused macrophages, extracellular bacilli, dead macrophage debris
- newly recruited activated macrophages and T cells (CD4 and CD8)
what is the granuloma walled off by
name of the final product
importance of this
- fibrin coat
- tubercle
- what you can see on the X ray
what is LTBI
- latent TB infection kept under control by cell mediated immune response
what is active TB
- reactivation of TB occurs and triggers an overly robust cell mediated immune response leading to lung damage and symptoms of infectious TB
what happens in the cell that can help us realize the transition to active TB
- granulomas liquifying and becoming and becoming a site for extracellular replication of TB
symptoms of TB are due to
- cytokine production (IL-1, TNF-alpha)
- macrophage activation
- CTLs
TB in HIV+ individuals
why
- primary infection not contained allowing MTB dissemination throughout the body leading to milliary TB
they don’t have enough T cells to wall off TB
miliary TB differential diagnosis include
- fungi
- metastatic tumor
chance of TB reactivation after HIV infection
- 10% each year
IGRA test measures
- IFN gamma production by T cells upon recognition of TB specific antigens not found in BCG
MTB/RIF test measures
- PCR for detection of MTB
- also determines rifampicin resistance
which TB drugs are pro-drugs first
- INH (Isoniazid)
- PZA (Pyrazinamide)
cause of leprosy
- Mycobacterium leprae
forms of leprosy and type of response
- tuberculoid leprosy (TH1 response)
- lepromatous leprosy (TH2 response)
which form of leprosy is deformity due to nerve damage with its consequent ulcers and resorption of bone
- tuberculoid leprosy
which form of leprosy is activated nodulous lepromatous leprosy
- lepromatous leprosy
atypical mycobacteria common where in the US
- southern and midwestern US
mycobacterium avium complex found where
- water supply
mycobacterium avium transmitted by
- inhalation or ingestion
mycobacterium avium causes
- pulmonary or disseminated disease
mycobacterium abscessus frequent in which patients
- bronchiectasis, COPD and CF patients
mycobacterium abscessus causes which infection
- chronic lung infection
- skin/soft tissue infections
mycobacterium abscessus treatable with drugs?
- highly resistant to drugs
mycobacterium fortuitum infections associated with
- nail salons & tattoo parlors
