mycobacteria

Question 1

why dont mycobacteria gram stain well ?

Answer 1

due to the presence of mycolic acid in the cell wall

Question 2

what stain is used for mycobacteria ?

Answer 2

ziehl neelsen

Question 3

what is the most common non TB mycobacterial infections ?

Answer 3

MAC

Question 4

what is the classic patient associated with MAC and what are the associated findings ?

Answer 4

usually associated with HIV/AIDS patients
very low CD4 count less than 50
fever sweats w keda
severe anemia
hepatosplenomegaly
inc ALP inc LDH
often no lung findings on chest x ray

Question 5

how is a diagnosis of MAC made ?

Answer 5

blood culture but very slow

Question 6

what is the treatment and prophylaxis of MAC ?

Answer 6

treatment is clarithromycin and ethambutol
prophylaxis: azithromycin

Question 7

what is the cause of leprosy and what is the other name for this disease ?

Answer 7

mycobacterium leprae
also called hansens disease

Question 8

what is the reservoir for leprosy ?

Answer 8

armadillos

Question 9

what are the most ideal growing environments for leprosy ?

Answer 9

they cannot be cultured and grow best on cold surfaces so they grow on the face and hands

Question 10

what type of inflammation is associated with leprosy ?

Answer 10

granulomatous inflammation

Question 11

what are the symptoms of leprosy ?

Answer 11

infects the skin and superficial nerves
associated with skin lesions and loss of sensation

Question 12

what is the severity of the spectrum of the disease of leprosy dependant on ?

Answer 12

depends on the cell mediated response

Question 13

what are the two types of leprosy ?

Answer 13

tuberculoid leprosy - milder disease patches of hypopigmented skin
lepromatous leprosy - severe disease diffuse hypopigmentation with hair loss

Question 14

what causes tuberculoid leprosy vs lepromatous leprosy ?

Answer 14

tuberculoid leprosy - strong cell mediated Th1 response , lesion shows mgranulomas but few bacteria
lepromatous leprosy - mediated by a Th2 response associated with multiple bacteria and few granuloma

Question 15

how is the diagnosis of leprosy made ?

Answer 15

CANNOT BE CULTURED
acid fast organisms on skin biopsy

Question 16

what test can give a false positive for leprosy ?

Answer 16

VRDL

Question 17

what is the treatment for leprosy ?

Answer 17

tuberculoid - dapsone and rifampcin
lepromatous - dapsone , rifampcin and clofazimine

Question 18

what is the mechanism of each of these drugs :
Rifampin
Dapsone
Clofazimine

Answer 18

Rifampin - blocks RNA synthesis
Dapsone - competes with PABA
Clofazimine - disrupts the DNA

Question 19

what are the diseases that need dapsone ?

Answer 19

leprosy
pneumocystis jirovecii

Question 20

why must dapsone be avoided in G6PD ?

Answer 20

may trigger hemolysis

Question 21

what drug works similarly to dapsone ?

Answer 21

sulfonamide

Question 22

what is the function of IL-12 ?

Answer 22

triggers the differentiation T cells to Th1 cells
Th1 cells produce IFN gamma

Question 23

what does IL12 receptor deficiency result in ?

Answer 23

disseminated salmonella
disseminated NTM
disseminated BCG after vaccine

Question 24

what is the treatment of IL 12 receptor deficiency ?

Answer 24

IFN gamma

Question 25

for what type of response is IL 12 important for ?

Answer 25

important for intracellular infections

Question 26

what type of mycobacterium is associated with cervical lymphadenitis in children ?

Answer 26

mycobacterium scrofulaceum

Question 27

what type of mycobacterium is associated with aquarium handlers ?

Answer 27

mycobacterium marinum

Question 28

what are the virulence factors associated with mycobacterium tuberculosis ?

Answer 28

cord factor - serpentine cord which activated=s macrophages and allows for the formation of granuloma and induces the release TNF alpha sulfatides- inhibits phagolysosomal fusion

Question 29

what test is associated with less false positives when it comes to testing for TB ?

Answer 29

IGRA assay PPD has more false negatives

Question 30

what is histologically characteristic of secondary tuberculosis ?

Answer 30

caseating granuloma with central necrosis and langhans giant cell

Question 31

where is reactivation of TB most likely to happen and what type of patient is more associated with reactivation ?

Answer 31

in the apices of the lung because the bacteria is highly aerobic more common in immunocompromised patients

Question 32

what is the distribution of neuropathy in leprosy ?

Answer 32

glove and sock neuropathy