7.2 Mycobacteria Flashcards
(14 cards)
Mycobacterium tuberculosis - infectious dose
extremely low 1-10 bacteria
how is TB transmitted
cough and sneeze
TB is endemic meaning
present ion a routine basis where population is higher and medicine is less available
asymptomatic
asymp means individual is not displaying symptoms of disease but still can carry and spread disease to other individuals
co-infection w TB and…
HIV - very dangerous many people die from this
vaccine is available but
does not provide lasting protection
– BCG
what is the hallmark of TB
the tubercule
what is a tubercule
granuloma that exists after M. tb replication within a macrophage.
granuloma
assortment of host cells that has walled off the bacteria so it does not replicate and cause severe/sudden disease
most of the bacteria are killed but..
some survive in a latent (dormant) form
in Dormant form
bacteria is still viable but not actively replicating
– bacteria avoide a full active imune response, being undetecable by host because in granuloma.
dormant pathogen can be activated again when…
host or individual undergoes additional stress that weakens the immune system
some macrophages are infected with mycobacterium
bacteria can replicate inside the macrophages. therefore, even though macrophages are meant to engulf these bacteria, the bacteria are resistant and can often survive (hijack immune host cell)
delta region of difference PAI
BCG vaccine strain is missing genes in this PAI – the genes in the PAI are important for M. tb for example esxB and esxA
- therefore the absence of these genes in the BCG vaccine makes it less virulent and attenuated, why can be used as a vaccine - because the lack of esxB and esxA is what causes the disease.
