Bacteria- Ch23 Mycobacteria

Question 1

what is in the cell wall of mycobacteria

Answer 1

mycolic acids

Question 2

describe the type of microbe mycobacteria is

Answer 2

• gram positive
• weak staining: use acid fast stain or specific fluorescent detection
• facultative intracellular growth in macrophages
  -obligate aerobe

Question 3

how is mycobacteria transferred

Answer 3

airborne- as few as 10 cells can result in infection

Question 4

what are reservoirs for mycobacteria

Answer 4

humans

Question 5

describe an acid fast stain

Answer 5

hot carbol fuchsin

Question 6

describe the mycobacterial cell wall structure

Answer 6

cord factor- glycolipid

Question 7

what are virulence factors for mycobacteria

Answer 7

-structural mycobacterial cell wall components- mycolic acid moiety
-inhibition of phagolysosome fusion

Question 8

what does mycolic acid slow cord like growth result from

Answer 8

adherence of cell surface lipid mycolic acids and glycolipids

Question 9

what does the virulence of mycobacteria result from

Answer 9

they provide a challenge to the immune response such as CD4+ T cells and macrophages because the disease is caused by the immune response not by the mycobacteria itself

Question 10

what potentiates cord factor effects

Answer 10

sulfatides

Question 11

how long does mycobacteria last in the body

Answer 11

lifelong, once infected you may be asymptomatic but never cured

Question 12

what does a CMI to mycobacterium tuberculosis look like

Answer 12

TB granuloma surrounded by puncate nuclei of lung tissue and inflammatory leukocytes. central area of necrosis where nuclei have been destroyed

Question 13

effective CMI is capable of _________ infection by M tuberculosis

Answer 13

localizing and stopping

Question 14

what is the typical result of aerosol transmission of mycobacterium tuberculosis

Answer 14

chronic TB

Question 15

what is the exception to aerosol transmission to mycobacterium tuberculosis

Answer 15

young children under 5 have a high risk for developing progressive TB due to insufficient immune system development

Question 16

what are the outcomes of untreated TB

Answer 16

-91% no disease
-6% clinical TB (2% pulmonary + 3% extrathoracic + 1% both)
- 3% progressive systemic disease and death

Question 17

what is another name for acute TB and what is it caused by

Answer 17

secondary tuberculosis or galloping consumption caused by endogenous reactivation of prior infection

Question 18

what is endogenous reactivation of acute TB stimulated by

Answer 18

stress, malnutrition and HIV

Question 19

what does the disease of mycobacterium tuberculosis arise from

Answer 19

tissue destruction by our immune defenses and not by damage caused by the bacterial infection

Question 20

what causes impaired lung function in mycobacterium tuberculosis infections

Answer 20

the repeated attempts to remove foci of infection by lung macrophages cause the granulomatous lung tissue

Question 21

what is breathing impairment in TB due to

Answer 21

the macrophage induced tissue destruction

Question 22

what is the mantoux reaction

Answer 22

a positive tuberculin test to subdermal PPD (processed protein derivative of the cell wall of the opportunistic intracellular pathogen mycobacterial tuberculosis)

Question 23

what is a positive test and strongly positive test in the mantoux reaction

Answer 23

-positive test: >10 mm redness
- strongly positive: >20 mm red

Question 24

what is the vaccination for mycobacteria

Answer 24

exposure to living attenuated mycobacterium, known as bacille calmette guerin (BCG) a derivative of M bovis

Question 25

what type of vaccine is BCG vaccine

Answer 25

- little virulence in humans (infectious in immune compromised people) - some protective immunity ( when given to young children)

Question 26

why is BCG vaccination discouraged in the USA

Answer 26

because it gives a positive tuberculin test, thus removing an important diagnostic screening tool

Question 27

what type of disease is TB

Answer 27

opportunistic

Question 28

what has caused a recent increase in TB

Answer 28

HIV and AIDS

Question 29

what is the number for world wide latent M tuberculosis infections

Answer 29

~ 2 billion -USA: 13 million

Question 30

what is the number for world wide TB deaths

Answer 30

~ 1.6 million/ year -USA: 500

Question 31

what are the treatments for TB

Answer 31

isoniazid

Question 32

what are the preferred targets for mycobacterium leprae

Answer 32

peripheral nerves

Question 33

what happens in a Th1 response to mycobacterium leprae

Answer 33

-tuberculoid -macrophages kill nerves -macules and plaques without sensation -good prognosis for recovery not infectious

Question 34

what happens in a lepromatous infection

Answer 34

bad prognosis for recovery -highly infectious

Question 35

what happens in loss of CMI to mycobacterium leprae and what is this type of response called

Answer 35

-CTL lysis and loss of tissue including nerves - AKA Th2 response

Question 36

what do histology slides of m leprae look like

Answer 36

beaded acid fast rods

Question 37

describe a tuberculoid plaque

Answer 37

without sensations, resulting from macrophage action after TH1 cytokine (IFNgamma activation)

Question 38

what happens in Th2 leprosy

Answer 38

cytokine (IL4) activation of CTL tissue lysis

Question 39

what is the multidrug therapy for tuberculoid and lepromatous leprosy

Answer 39

dapsone + rifampin +clofazimine

Question 40

describe tuberculoid granuloma

Answer 40

- no or few bacteria - low infectivity - ag- specific Th1 - no Ag specific IgG - normal Ig level

Question 41

describe leprosy

Answer 41

- many bacteria inside macrophages - high infectivity - extensive tissue damage - no T- response to Ag - sometimes Ag- specific IgG - hyper Ig level

Question 42

what are the virulence factors, clinical features, treatment, and epidemiology for M. tuberculosis

Answer 42

- ability to survive and live in lung macrophages - pulmonary and extrapulmonary tuberculosis - mutlidrug therapy for 6-12 months - aerosol, all ages, highest risk if immune compromised such as HIV

Question 43

what are the virulence factors, clinical features, treatment, epidemiology for M. leprae

Answer 43

-ability to survive and live in macrophages - tuberculoid-to- lepramatous leprosy - multidrug therapy for 2+ years - close physical contact

Question 44

all pathogenic mycobacterial species have ________ growth rates

Answer 44

very slow

Question 45

when is isoniazid used other than mycobacterium infections

Answer 45

prophylactically upon conversion to a positive mantoux reaction

Question 46

what does ethambutol do

Answer 46

inhibitor of enzymes that synthesize non-mycolic acid cell wall components

Question 47

what does pyrazinamide do (PZA)

Answer 47

mechanism of action is unknown

Question 48

what type of microbe is nocardia

Answer 48

- gram positive - partially acid fast - poor stinaing - mycolic acid in cell wall: partially acid fast

Question 49

what is the difference between nocardial mycolic acid and mycobacterial mycolic acid

Answer 49

-nocardial: 50-62 x C - mycobacterial: 70-90 x C

Question 50

what are the virluence factors for nocardia

Answer 50

-opportunistic pathogen in immuno compromised patients - antiphagocytic virulence factors of strictly aerobic nocardia - intracellular survival and growth - catalase - superoxide dismutase

Question 51

what are the clinical features, treatment and epidemiology for nocardia

Answer 51

- bronchopulmonary cutaneous infections and brain abscesses - sulfonamides, amikacin, carbapenems, or cephalosporins - opportunistic pathogen if pulmonary disease of T deficiency