Transcript Mycobacterium Tuberculosis

R. Siddiqui F2013
Modified by DYH
Mycobacterium tuberculosis
General Characteristics:
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Mycobacterium tuberculosis is the causative
agent for the tuberculosis disease in humans.
The bacterium is nonmotile and rod-shaped
(bacilli).
Facultative intracellular parasite, as well as an
obligate aerobe
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This can explain why tuberculosis is a disease that typically
affects the lungs.
Cell wall contains peptidoglycan and lipids, longchain alpha-alkyl, beta-hydroxy fatty acids.
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Gram-stain and more
Also contains mycolic acids, cord factor, and wax-D.
Mycolic acids are significant for virulence in
mycobacterium tuberculosis
Cord Factor: winding-curved cording, toxic to
mammals.
Wax-D: located in the cell envelope (Kenneth
2008)
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Mycobacterium tuberculosis is not
considered gram-positive or gram-negative
bacteria.
However, the bacterium may weakly stain
gram-positive when gram-stained.
Mycobacterium tuberculosis is an acid-fast
bacteria (can be impermeable to many stains
and dyes).
DNA Characteristics:
-DNA found in macrophages, as well as phagocytic
cells
-posses many genes that contribute to base excision
repair, nucleotide excision repair, recombination
repair, etc. *These characteristics can explain why
Mycobacterium tuberculosis is able to withstand
environmental stresses, such as UV radiation.
www.medschool.lsuhsc.edu/pathology/pathist/SURGPATH/special%20stai
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R. Siddiqui F2013
Modified by DYH
Mycobacterium tuberculosis
Pathenogenesis:
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Infection of host primarily in lungs.
Once in the lungs, the bacteria are engulfed within
alveolar macrophages, and remain in endocytic
compartments where they mature to become
phagosomes.
The mycobacterium tuberculosis species are able to
inhibit phagosome-lysosome fusion, thus preventing
their destruction.
Formation of granulomas allows infection o effectively
remain in the lungs without dissemination.
(Forrelad 2013)
Invasins:
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mce1A has been identified as a gene that plays a role
in the invasion of nonphagocytic cells.
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Cell wall proteins include the outer membrane
proteins (OMPs).
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play a role in adhesion, and invading the host cell.
-OMPs also play a role in in degrading host structures.
****These are all factors that contribute to the species
impermeability to stains and dyes, antibiotic resistance,
resistance to lysis from host, etc.
Virulence Factors:
-Mycobacterium tuberculosis contain virulence genes that
encode enzymes of many lipid pathways, cell surface
proteins, and regulators and proteins of signal transduction
systems (Forrelad 2013)
-Additional virulence gene allows for survival of conditions
inside host macrophages.
http://stateschronicle.com/wpcontent/uploads/2013/09/Mycobacterium_tuberculosi
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http://www.nature
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