Mycobarterea

Question 1

What are characteristics of mycobacterium?

Answer 1

Aerobic, non-spore-forming, non-motile, slightly curved or straight rods

Question 2

True or false

All the mycobacterium is non-spore-forming bacteria’s!

Answer 2

False

M.marinum is spore-forming bacteria.

Question 3

What is colonial characteristics of mycobacterium?

Answer 3

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

Question 4

Why mycobacterium has slow growth on culture?

Answer 4

Is slow grower because it has single copies of ribosomal genes

Question 5

How can we distinguish M.Tuberculosis from other mycobacterium?

Answer 5

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.

Question 6

What is cord factor or trehalose mycolaate func fear in T.B?

Answer 6

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

Question 7

What is salfatide role in T.B?

Answer 7

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.

Question 8

Why at first immune system kill the t.b?

What is characteristics of t.b when T-cells are activated?

Answer 8

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.

Question 9

Most dominant symptoms of seconding TB?

Answer 9

Cough, hemoptysis, night sweat, fever, anorexia and weight loss are the more dominant symptoms.

Question 10

What ‘s Extrapulmonary manifestations of M. tuberculosis infection?

Answer 10

cervical lymphadenitis, pleuritis, pericarditis, synovitis, meningitis, and infections of the skin, joints, bones, and internal organs

Question 11

Which culture used for tb

Answer 11

Lowenstein-Jensen

Question 12

How do tb appears on culture?

Answer 12

Pale yellowish colonies on green slant of culture media.

Question 13

How to do skin test for tb?

And when they are considered positive?

Answer 13

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.

Question 14

How to treat t.b?

Answer 14

Isoniazid, rifampin, pyrazinamide and ethambutol are administrated for 2 months followed by 4 months of isoniazid and rifampin

Question 15

Characteristics of M. Leprae?

Answer 15

Chronic, gronulomatous, and debilitating disease (making them very weak )
Also anesthetic skin lesion and peripheral neuropathy with nerve thickening

Question 16

What are M. Leprae forms?

Answer 16

tuberculoid leprosy → lepromatous leprosy.

Question 17

What’s lost of M. Leprae?

Answer 17

armadillo

Question 18

How much acid much is needed for M. Leprae?

Answer 18

10% sulfuric acid is preferentially used as a decolorize in place of an acid-alcohol solution

Question 19

What are characteristics of nocardia infections?

Answer 19

Nocardia is a filamentous soil bacterium that fragments into rods. Is aerobic ,G+ve and partially Acid-fast. Related to Corynebacterium, Mycobacterium and Actinomycetes.

Question 20

What are cultural characteristics of nocardia?

Answer 20

Aeroherc, some species is acid fest, has cord factor

They are also catalyze positive on blood agar

Question 21

Nocardia asteroids is opportunistic infecton what is it’s virulence factor?

Answer 21

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)

Question 22

Which species of nocordia mostly cause cutaneous nocardiosis?

Answer 22

N. brasiliensis

Question 23

True or false

25-33% of people Nocardia infection takes the form of encephalitis and/or brain abscess formation.

Answer 23

True

Question 24

How to treat nocardia?

Answer 24

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.

Question 25

What is fate of primary infection by T.B?

Answer 25

Activation of macrophages and t-cells lead to granuloma formation.
Gaseous necrosis occurs in the center of gronuloma.

Question 26

Which species is mostly confused with T.B?

Answer 26

Nocardia asteroides

Question 27

What is characteristics of nocardia asteroids?

Answer 27

Low virulence, opportunistic infection, virulence factors are enzyme catalase and superoxide dismutase as well as cord factors.

Question 28

What is catunous verity of infection of Nocordia?

Answer 28

variety of cutaneous infections such as actinomycetoma (especially N. brasiliensis), lymphocutaneous disease, cellulitis, and subcutaneous abscesses.