Bacteria: Mycobacteria Flashcards
List the 2 Mycobacterium
- Mycobacterium Tuberculosis
2. Mycobacterium Leprae
Mycobacterium tuberculosis
- acid-fast bacterium
- Mycobacterium
- obligate aerobes
Mycobacterium tuberculosis bacteria stain acid-fast due to
high mycolic acid content in the cell membrane
carbol fuchsin is
a dye used to detect acid-fast bacteria, such as Mycobacterium tuberculosis
____________ _________ ________ is a growth medium used to culture Mycobacterium tuberculosis
Lowenstein-Jensen Agar
Mycobacterium tuberculosis bacteria replicate within
Macrophages
Cord Factor
cord factor produced by Mycobacterium tuberculosis is a membrane glycolipid responsible for clumping of bacterial cells into serpentine cords in vitro and for protection of bacteria against host defenses in vivo (strains that lack cord factor are not virulent)
Sulfatides
sulfatides produced by Mycobacterium tuberculosis are sulfolipids that prevent phagolysosome fusion (protecting bacterial cells from exposure to lysosomal hydrolases, allowing for intracellular survival)
Primary tuberculosis typically affects
the middle or lower lobes of the lungs
Lymphatic dissemination of Mycobacterium tuberculosis during primary tuberculosis can result in
hilar lymphadenopathy
A Ghon complex is
lung lesion that usually affects the middle or lower lobe of the lung consisting of hilar lymphadenopathy and a parenchymal granuloma
A ________ ______ can form during primary tuberculosis
Gohn Complex
The caseating granulomas of primary tuberculosis are
characterized by a central necrotic zone (necrotic macrophages and cellular debris) walled off by macrophages and lymphocytes
Latent tuberculosis infections occur
when dormant Mycobacterium tuberculosis bacteria are contained within walled-off foci
Primary tuberculosis usually resolves by
fibrosis of lung tissue (granulomas form to wall off Mycobacterium tuberculosis)
The purified protein derivative (PPD) skin test (or tuberculin skin test (TST)) involves
intradermal injection of Mycobacterium tuberculosis antigen; an induration >15 mm (in immunocompetent patients who are low-risk of exposure) at 48 to 72 hours is considered a positive result
The bacille Calmette-Guerin (BCG) vaccine for tuberculosis
may cause a false-positive reaction to the purified protein derivative/tuberculin skin test
Miliary Tuberculosis
- miliary tuberculosis occurs when the immune system fails to clear the infection, resulting in diffuse hematogenous dissemination of tuberculosis to multiple organs
- Potentially fatal infection
Reactivation of latent tuberculosis is associated with use of
TNF-alpha inhibitors
TNF alpha is important for
granuloma formation and maintenance
Reactivation (secondary) tuberculosis
- typically affects the upper lobes of the lungs
2. may present with cough hemoptysis and night sweats
Pott disease
is an infection of the vertebral column (usually affecting the lower thoracic and upper lumbar region) that results from dissemination of Mycobacterium tuberculosis from other sites (Pott disease can result from progressive primary or reactivation (secondary) tuberculosis)
Progressive primary tuberculosis or reactivation (secondary) tuberculosis can
disseminate to the CNS and cause cavitary lesions and tuberculomas in the brain
Treatment for tuberculosis
- the combination of rifampin, isoniazid, pyrazinamide, and ethambutol (RIPE) is administered for (typically symptomatic) tuberculosis to combat and further prevent drug-resistant strains
- rifampin and isoniazid can be used in cases of latent tuberculosis to prevent reactivation
Mycobacterium leprae
- acid-fast bacterium
2. Mycobacterium
Mycobacterium leprae thrives
in cooler temperatures and, therefore, has a predilection for the extremities
Mycobacterium leprae bacteria stain acid-fast due to
high mycolic acid content in the cell membrane
carbol fuchsin is a stain used to visualize
acid-fast bacteria, such as Mycobacterium leprae
_______ are the main reservoir of Mycobacterium leprae in the United States
armidillos
The response to tuberculoid leporsy is
propagated by Th1 (T helper type 1) cells, which incite a cell-mediated immune response
A strong Th1 (T helper type 1) cell-mediated immune response induces
macrophage phagocytosis of Mycobacterium leprae bacteria, resulting in the tuberculoid variant of leprosy
Tuberculoid leprosy is characterized by
well-demarcated, hairless skin lesions
The lepromin skin test involves
injection of inactivated Mycobacterium leprae under the skin; a positive test indicates cell mediated immunity and tuberculoid leprosy
The response to lepromatous leprosy is propagated by
Th2 (T helper type 2) cells, which promote the humoral immune response
A Th2 (T helper type 2) humoral immune response in lepromatous leprosy is
correlated with a weak or nonexistent Th1 (T helper type 1) cell-mediated immune response, preventing the containment of Mycobacterium leprae bacteria within macrophages
Lepromatous leprosy is spread via
human-to-human transmission
Lepromatous leprosy may present with
symmetric “glove and stocking” neuropathy in the extremities
Lepromatous leprosy presents with
poorly demarcated lesions on the extensor surface of the extremities
Leonine facies deformity
leonine facies deformity seen in lepromatous leprosy often involves thickening of the skin, loss of eyebrows and eyelashes, collapse of the nose, and formation of nodular earlobes
Treatment for tuberuloid leprosy
a 6 month course of dapsone and rifampin is an effective treatment against tuberculoid leprosy
Treatment for lepromatous leprosy
a 2-5 year course of dapsone, rifampin, and clofazimine is an effective treatment against lepromatous leprosy
