Mycobarterea Flashcards
What are characteristics of mycobacterium?
Aerobic, non-spore-forming, non-motile, slightly curved or straight rods
True or false
All the mycobacterium is non-spore-forming bacteria’s!
False
M.marinum is spore-forming bacteria.
What is colonial characteristics of mycobacterium?
Colony morphology varies among the species, ranging from smooth to rough and from non-pigmented (non-photochromogens) to pigmented.
Pigmented colonies are regularly or variably yellow, orange, or, rarely, pink
Why mycobacterium has slow growth on culture?
Is slow grower because it has single copies of ribosomal genes
How can we distinguish M.Tuberculosis from other mycobacterium?
M.Tuberculosis is distinguish from other mycobacteriaceae by substantial Niacin production & the presence of a heat sensitive catalase, which is functional at body temperature but not at 68 C.
What is cord factor or trehalose mycolaate func fear in T.B?
Cord factor( trehalose mycolate) on the cell surface of a virulence factor that:
1 disrupts mitochondrial membranes
2 interfering with respiration and oxidative phosphorylation
3 Inhibit neutrophil migration
What is salfatide role in T.B?
Salfatides: (sulfur containing glycolipids) potentate the toxicity of the cord factor and promote intracellular survival by inhibiting the phagosome-lysosome fusion and suppressing superoxide formation.
Why at first immune system kill the t.b?
What is characteristics of t.b when T-cells are activated?
mycobacteria are picked up by phagocytic cells but are not killed; they replicate, killing the phagocyte.
The activation of marcophages and t- cells sensitization leads to granuloma formation.
Most dominant symptoms of seconding TB?
Cough, hemoptysis, night sweat, fever, anorexia and weight loss are the more dominant symptoms.
What ‘s Extrapulmonary manifestations of M. tuberculosis infection?
cervical lymphadenitis, pleuritis, pericarditis, synovitis, meningitis, and infections of the skin, joints, bones, and internal organs
Which culture used for tb
Lowenstein-Jensen
How do tb appears on culture?
Pale yellowish colonies on green slant of culture media.
How to do skin test for tb?
And when they are considered positive?
Skin test: a purified protein derivates(PPD) of M.tuberculosis.
considered positive if the zone of induration measures:
a. Above than 15 mm in a person not known to have exposure.
b. Above than 10 mm in individuals from countries of high risk
c. Above than 5 mm in HIV or with recent known exposure.
How to treat t.b?
Isoniazid, rifampin, pyrazinamide and ethambutol are administrated for 2 months followed by 4 months of isoniazid and rifampin
Characteristics of M. Leprae?
Chronic, gronulomatous, and debilitating disease (making them very weak )
Also anesthetic skin lesion and peripheral neuropathy with nerve thickening
What are M. Leprae forms?
tuberculoid leprosy → lepromatous leprosy.
What’s lost of M. Leprae?
armadillo
How much acid much is needed for M. Leprae?
10% sulfuric acid is preferentially used as a decolorize in place of an acid-alcohol solution
What are characteristics of nocardia infections?
Nocardia is a filamentous soil bacterium that fragments into rods. Is aerobic ,G+ve and partially Acid-fast. Related to Corynebacterium, Mycobacterium and Actinomycetes.
What are cultural characteristics of nocardia?
Aeroherc, some species is acid fest, has cord factor
They are also catalyze positive on blood agar
Nocardia asteroids is opportunistic infecton what is it’s virulence factor?
1- enzyme catalase
2-superoxide dismutase
3. Cord factor (which interferes with phagocytosis by macrophages by preventing the fusion of the phagosome with the lysosome)
Which species of nocordia mostly cause cutaneous nocardiosis?
N. brasiliensis
True or false
25-33% of people Nocardia infection takes the form of encephalitis and/or brain abscess formation.
True
How to treat nocardia?
Trionethoprim-sulfamethoxarole is treatment of choice
People who take trimethoprim-sul for other reasons, such as prevention of Pneumocystis jirovecii infection, appear to have fewer Nocardia infections
Linezolid appears to be highly effective against Nocardia, but it is very expensive and may cause severe adverse effects.
Antibiotic therapy is continued for six months (in immunocompetent people) to a year (in immunosuppression), and may need to be continued indefinitely.
What is fate of primary infection by T.B?
Activation of macrophages and t-cells lead to granuloma formation.
Gaseous necrosis occurs in the center of gronuloma.
Which species is mostly confused with T.B?
Nocardia asteroides
What is characteristics of nocardia asteroids?
Low virulence, opportunistic infection, virulence factors are enzyme catalase and superoxide dismutase as well as cord factors.
What is catunous verity of infection of Nocordia?
variety of cutaneous infections such as actinomycetoma (especially N. brasiliensis), lymphocutaneous disease, cellulitis, and subcutaneous abscesses.
