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Fall 22: micro > Test 1: lecture 6: mycobacterium > Flashcards

Test 1: lecture 6: mycobacterium Flashcards

1
Q

what stain is used for mycobacteria

A

Ziehl-neelsen staining

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2
Q

the outer membrane of mycobacteria contain ___ and ___

A

mycolic acid

lipo-arabino-mannan

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3
Q

what shape is mycobacteria

A

gram + bacilli

(acid fast +)

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4
Q

what three bacteria are acid fast +

A

mycobacterium

nocardia

rhodococcus

(all gram + rods)

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5
Q

what type of bacteria are non acid fast

A

corynebacterium

actinomyces

dermatophilus

trueperella

(gram + rods of the actinomycetia family, no spores)

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6
Q

list the gram + rods

A
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7
Q

mycobacteria are important causes of human and animal ___

A

tuberculosis disease

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8
Q

what kind of animals are highly susceptible to TB?

A

elephants

can transfer from human to elephant to human

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9
Q

mycobacteria course of disease in most healthy individuals is ___ as long as immune function is maintained

A

asymptomatic

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10
Q

the function of what in the host is crucial for containment of mycobacteria

A

CD4+ T cells, IFNg, macrophage microbicidal mechanisms

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11
Q

TB lesions form ___ that have central caseating necrosis
surrounded by ____ and T cells

A

granulomas

‘epithelioid’ macrophages

(caused by mycobacteria gram + rod, acid fast +)

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12
Q

Johne’s disease is caused by ___

A

Mycobacterium avium subsp. Paratuberculosis

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13
Q

Mycobacterium avium subsp. Paratuberculosis causes ___

A

johne’s disease in cattle

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14
Q

mycobacteria cause debulitating ___ in cattle

A

Debilitating enteritis in cattle –

acquired during first 6 months of life, clinical disease appears 2-8 years later. Organisms shed before onset of clinical symptoms

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15
Q

3 important disease of mycobacteria

A

1) Leprosy
2) Tuberculosis
3) Paratuberculosis (Johne’s disease→ cattle)

(gram + rods, acid fast +)

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16
Q

sunlight promotes the production of ___ by macrophages

A

Vit D → IFN gamma in macrophages

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17
Q

4 important species of mycobacteria

A

1) M. leprae - - - - - - - leprosy in humans.
2) M. tuberculosis - - - TB in humans.
3) M. bovis - - TB in cattle, other animals & humans.

4) M. avium:
* *subspecies avium** - - -TB in chickens, other birds, some animals & in
(immunocompromised) humans.
* *subspecies paratuberculosis** – paratuberculosis (Johne’s Disease) of ruminants; infection of humans is controversial

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18
Q

___ cause leprosy in humans

A

1) M. leprae - - - - - - - leprosy in humans.

(gram + rod, acid fast +)

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19
Q

___ cause TB in humans

A

Mycobacteria tuberculosis

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20
Q

___ cause TB in cattle, other animals and humans

A

mycobacteria bovis

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21
Q

___ cause TB in chickens

A

Mycobacteria avium subspecies avium

(gram + rod, acid fast +)

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22
Q

___ cause paratuberculosis in ruminants

A

Mycobacteria avium subspecies paratuberculosis

(Johne’s Disease)

(might cause Crohn’s disease in humans??)

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23
Q

what are the two important subspecies of Mycobacteria avium

A
  • *subspecies avium -** - -TB in chickens, other birds, some animals & in
    (immunocompromised) humans.

subspecies paratuberculosis – paratuberculosis (Johne’s Disease) of ruminants; infection of humans is controversial

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24
Q

Ziel-Neelsen method is used for ___

A

mycobacteria are gram + but their cell wall do not react well with decolorization are appear weird gram - looking

bacteria is dyed with carbolfuchsin, then steamed, then decolorized with acidified alcohol (95% EtOH- 3 % HCl), then counterstained and produce Red rod shaped bacteria

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25
Q

steps of acid fast stain

A

bacteria is dyed with carbolfuchsin, then steamed, then decolorized with acidified alcohol (95% EtOH- 3 % HCl), then counterstained and produce Red rod shaped bacteria

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26
Q
A

ziehl-nellsen

acid fast staining

(mycobacteria, nocardia, rhodococcus all acid fast +, gram + rods)

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27
Q

besides for acid fast stain what is another way to identify mycobacteria

A

auramine fluorescent stain

auramine and rhodamine are flurochromes

(non specific fluorescence can cause a problem in clinical specimens)

(mycobacteria, nocardia and rhodococcus are gram + rods, + acid fast)

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28
Q
A

auramine fluorescent stain used to stain for mycobacterium

(gram + rod, acid fast +)

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29
Q

___ help stabilize mycobacteria cell wall

A

lipoarabino mannan

also have fatty acid mycolic acid

30
Q

___ give mycobacteria cell wall its hydrophobic character

A

mycolic acid → fatty acid

lipoarabino mannan

31
Q

compare the make up of the cell wall of Gram +, gram - and mycobacteria

A

gram + → open faced sandwhich → thick peptidoglycan

gram - → LPS outer layer and thin peptidoglycan in a periplasmic space

mycobacteria → gram + rods, acid fast +→ thick outer membrane of mycolic acid and lipoarabino mannan, thin peptidoglycan

32
Q

what are three tubercle bacilli

A

Mycobacteria tuberculosis

M. bovis

M avium (subspecies avium and subspecies paratuberculosis)

(mycobacteria, nocardia and rhodococcus are all acid fast +, rod shaped gram +)

33
Q

properties of tubercle bacilli

A

non motile aerobes

no spores

straight or slightly curved rods

sometimes filamentous

multiply slowly (14-24 hrs)

takes > 3-4 weeks to grow in culture

34
Q

tubercle bacilli such as ___ multiply every ___

A

M. tuberculosis, M. bovis and M avium

12-14 hrs (slow growing)

35
Q

tubercle bacilli such as ___ take ___ to grow in culture

A

M. tuberculosis, M. bovis and M avium

> 3-4 weeks

36
Q

tubercle bacilli are aerobes or anaerobes?

A

non motile aerobes

37
Q

how to grow mycobacteria in culture

A

lowenstein- jensen agar

high lipids and contain egg products, glycerol, potato flour and salt

malachite green in used to inhibit the growth of other bacteria → mycobacteria very slow growing, need to kill off other bacteria to allow them to grow

38
Q

lowenstein-jensen agar is used to grow

A

mycobacterium

very slow growing → malachite green added to kill off other bacteria

high in lipids, glycerol, salt and potato flour

39
Q

mycobacteria can survive moderate ___

A

heat but will be killed by pasteurization

40
Q

mycobacteria is resistant to ___

A

desiccation (drying)

most aqueous disinfectants→ acids and bases

41
Q

___ is used to kill mycobacteria

A

phenol and alcohol

direct sunlight

42
Q

2 common resistant TB strains

A

MDR - multi-drug resistant

XDR- extensively drug resistant

43
Q

____is defined as resistance to isoniazid and rifampin, plus resistance to any fluoroquinolone and at least one of three injectable second-line anti-TB drugs

A

XDR TB

44
Q

Packy of Oregon Zoo had ___

A

TB

got it from humans and could pass to other elephants and humans

45
Q

3 routes of infection for TB

A

inhalation

ingestion

percutaneous

(TB caused by mycobacteria→ gram + rod, acid fast +)

46
Q

ingestion of mycobacteria leads to lesions in the ___

A

intestinal tract, lymph nodes, liver, and spleen

(would happen a lot before milk pasteurization)

47
Q

what route of infection of TB is rare

A

percutaneous → infection after skin inoculation cause lesions in the skin, skin draining lymph nodes

TB caused by mycobacteria (gram + rod, acid fast +)

48
Q
A

miliary TB

rare

granulomas form in the lungs of immuncompromised cattle

caused by mycobacteria (gram + rods, acid fast +)

49
Q

BCG

A

Bacillus Calmette Guerin (BCG) vaccine for TB

not used in animals because it can cause false positive TB skin tests

most effective for childhood tuberculous meningitis and miliary disease

50
Q

are there vaccines for TB

A

not really

can use Bacillus Calmette Guerin (BCG) vaccine but causes false positive TB skin test and not very effective

51
Q

immune response to M. Tb and M. bovis

A

bacteria infect macrophages and dendritic cells that activate CD4 Tcells to produce IFN gamma and TNF alpha which leads to increased macrophages and granuloma formation

52
Q

how does skin test for TB work

A

delayed hypersensitivity response

inoculated with a PPD (purified protein derivative)

if previous exposure memory T cells will release IFN gamma and cause tissue swelling

will get response if had TB in past or if they had BCG vaccination

53
Q

what kind of diagnostic test for mycobacteria TB

A

chest xray

acid fast staining and culture

PPD skin test

IFN gamma release assays → Elisa testing

54
Q

QuantiFERON-TB Gold and T-SPOT.TB

A

IFN gamma release assays

testing for memory cells for antigens of M. bovis and M. avium that release INF gamma

will not cause false positive if previous BCG vaccination

55
Q

how to control TB in food production

A

cull infected animals and monitor for lesions although most cattle show no lesions

(caused by mycobacteria → gram + rods, acid fast +)

56
Q

why is it not recommended to treat TB in pets

A

requires multiple antibiotics over a long course

Isoniazid, rifampin, ethambutol, pyrazinamide.

can lead to resistance

57
Q

what drugs are used to treat TB

A

Isoniazid, rifampin, ethambutol, pyrazinamide.

long treatment 6-12 months!

58
Q

MAP

A

Mycobacterium avium subspecies paratuberculosis

Johne’s disease

(gram +, short thick rods, acid fast +)

bacteria produce mycobactin that allows bacteria to scavenge iron from their environment

parasitic pathogen

takes 6-12 weeks to grow in culture

59
Q

how long does it take to grow Johne’s disease in culture

A

Mycobacterium avium subspecies paratuberculosis (MAP) (gram +, short fat rods, acid fast +)

6-12 weeks

60
Q

what type of gram + rod are obligate parasitic pathogens?

A

Mycobacterium avium subspecies paratuberculosis (MAP)

Johne’s disease

produce mycobactin that steal iron from the host

61
Q

resistance of MAP

A

same things as tubercle bacilli → moderate resistance to heat, resistance to drying, fair resistance to disinfectants such as acids and bases, killed by alcohol, sensitive to direct sunlight

but

can survive for 250 days in the environment, can’t replicate but just sits there waiting for a host

62
Q

wasting

A

cachexia

63
Q

Johne’s disease

A

caused by Mycobacterium avium subspecies paratuberculosis (MAP)

gram + short rods, acid fast +

chronic, debilitating enteritis in cattle, sheep, goats and other ruminants resulting in diarrhea, cachexia (wasting), and eventual death.

leads to decreased milk production

symptoms start 2 years after infection

around 22% of dairy and 8% of beef infected

transmitted by fecal/oral route, in utero and during milking

64
Q

chronic, debilitating enteritis in cattle, sheep, goats and other ruminants resulting in diarrhea, cachexia (wasting), and eventual death.

A

Johne’s disease

caused by Mycobacterium avium subspecies paratuberculosis (MAP)

gram + short rods, acid fast +

65
Q

pathogenesis of johne’s disease

A

caused by Mycobacterium avium subspecies paratuberculosis (MAP)

gram + short rods, acid fast +

eaten by macrophages in peyer’s patches and intestinal mucosa → resistant to being killed and will slowly replicate which cause inflammation and granuloma formation in the wall of the intestine

66
Q
A

caused by Mycobacterium avium subspecies paratuberculosis (MAP)

johne’s disease

gram + short rods, acid fast +

67
Q

3 ways to diagnose Johne’s disease

A

Fecal culture, 12-16 wks
– most sensitive & most reliable

Serum antibody tests
– less expensive, faster
– becomes more reliable as disease progresses

PCR
– fast, as sensitive as fecal culture but expensive.

68
Q

is there a vaccine for Johne’s disease

A

yes but not really used

does not stop infection or shedding, more prevents calves from getting it

causes false positive tests

69
Q

how to treat Johne’s disease

A

drugs not very effective- expensive don’t really work

cull infected

move babies away from adults

very hard to remove

caused by Mycobacterium avium subspecies paratuberculosis (MAP)

70
Q

MAP infection common in humans with __disease.

A

Crohn’s

Mycobacterium avium subspecies paratuberculosis (MAP)

(gram + short thick rod, acid fast +)

Fall 22: micro (25 decks)

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