Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pathophysiology > 2. Mycobacteria > Flashcards

2. Mycobacteria Flashcards

1
Q

What are mycobacteria?

A
  1. Slow growers
  2. Thick complex lipid-rich waxy cell walls
  3. Rod shaped
  4. Resist decolonization with acid or alcohol ( acid fast )
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the stain used for mycobacteria?

A

Not gram stain but Ziehl-Nelsen stain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens during the staining of mycobacteria?

A
  1. Carbul Fuchsin is used at the beginning ( have to heat them to accept the fuchsia
  2. Then use a counter ion normally blue staining so the background becomes blue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where can we culture mycobacteria?

A

Cultured on Lowenstein-Jensen (LJ) medium, which is specific for mycobacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How long does it take to see colonies of M.tubercolosis?

A

Up to 8 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the type of mycobacteria ( aerobes or anaerobes or facultative )

A

OBLIGATE anaerobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the type of mycobacteria ( pathogens / commensals / opp )?

A

M.TB & M.Leprae are OBLIGATE pathogens —> not part of our normal flora —> cause chronic disease —> produce infectious granulomatous lesions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the characteristics of ATYPICAL mycobacteria?

A

OPP pathogens in immunocompromised persons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is tuberculosis controlled ?

A

Yes

BCG ( bacil of calmet and Geran ) vaccine —> live attenuated strain of M.bovis —> given intradermally early after birth —> vaccine Scar on the fore arm —> booster dose can be given later at school entering time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the characteristics of M.bovis?

A
  1. Causes infection in cattle
  2. If it comes to humans it is pathogenic
  3. Attenuated: pass on culture medium for several times > 20 times —> found that it is now weakened to the extent to be a perfect vaccine so it will not induce the syms of the inf but it triggers the immune system to produce all what is necessary to have memory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What can BCG vaccine cause?

A

Induced delayed type hypersensitivity DTH ( bcz it induces similar response the same as if you get the infection )

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is DTH?

A
  1. Kind of allergy
  2. Marked by lots of inflammation and by recruitment influx of the delayed type of T helper cells and lots of macrophages
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the controversy on eff of the BCG vaccine ?

A

A. They thought that this vaccine is very eff —> once you take it during early life you are protected your whole life —> but this not the case now bcz there are lots of cases of TB that are seen in the pop of the people vaccinated with BCG

So, now there is controversy that is it good or not —> eliminated already in America and some countries but we still take it

B.it is live attenuated —> always a risk if live bacteria —> if cannot give it to children with HIV or CANCER

So,

  1. It is good for first 12 years
  2. Very eff against extra pulmonary TB but need to get booster dose during your life bcz it is not as thought to be life long
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the types of bacteria that can resist phagocytosis?

A

M. Tuberculosis and salmonella

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How can we diagnose tuberculosis?

A
  1. 1ry —> X-ray —> not very clear and you can’t know the stage of the disease
  2. Use purified protein derivatives ( PPD ) in Mantoux skin test —> test for hypersensitivity ( tuberculin reactivity ) bcz the person has reactivity against the tubercular test
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How is Mantoux skin test done?

A

A. Take the child to the clinic for booster dose of BCG

B. Give him an injection and draw a circle around it

C. After 24-48 hrs come back
1. If nothing happens / small non indurated —> fine and probably protected by the vaccine —> associated with protective immunity ( healthy people )

  1. If the child has fever or if it gets very inflamed, indurated, drainage,and painful —> have something active now like inf by M.tuberculosis
  2. If NO response at all —> child needs to be vaccinated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does Mantoux skin test contain?

A

It has lots of PPD proteins from the M.tuberculosis—> if introduced under the skin of the person —> causes detach similar to the vaccine

It is a prep standardized and can be bought from the pharmacy

18
Q

Tuberculin reaction results from what?

A
  1. DTH
  2. inflammation caused by lymphokines secreted by lymphocytes and macrophages especially TNF ( tumor necrosis factor )—> usually in DTH & inflammation
19
Q

What are the characteristics of M.TB ?

A
  1. Do not produce any toxin ( exotoxins )
  2. Pathogenicity ( VF ) rely on their ability to resist macrophage phagocytosis
  3. Development of the disease depend on the host’s( depend on the persons immune sys ) :
    A. Resistance
    B. Hypersensitivity
20
Q

What does the development of the disease depend on and how?

A

Whether the person will develop the infection or not will depend on the persons immune sys:

  1. If the immune sys will take to cellular response —> lots of good T helper cells ( cytotoxic cells ) —> person will overcome the disease and will not develop the infection —> clear in 1 month مثلا
  2. If the nature of his immune sys is to produce lots of DTH and lots inflammatory cells and lots of granuloma —> lots of hyper sensitivity —> get the infection with complications —> cells are dying and attacking —> necrosis of the cells ( bcz of our own immune sys Trying to attack the bacilli )
21
Q

What are the people who are infected by M.tuberculosis but not sick have ?

A

They have what is called latent TB

Could be
A. 1ry: with the person latent
B. 2ry: come after latent TB: after the 1ry infection he will clear lots of the bacilli but some foci will remain dormant ( after 10 years or many years if the person is immunocompromised it has another infection —> Foci get reactive

IT IS A CHRONIC INFECTION in

22
Q

What are the characteristics of people who have latent TB?

A
  1. Do not feel sick
  2. Do not have any syms
  3. Cannot spread TB to others
23
Q

What is 1ry TB?

A

Bacilli acquired by inhalation and the initial site of inf is the LUNGS

24
Q

Where can bacilli form lesions in 1ry TB ( resp tract inf )?

A
  1. Engulfed by alveolar macrophages —> form initial lesions —> ghon focus
  2. Transported to the hilar lymph nodes —> form lesions —> enlarged lymph nodes

1 + 2 = primary complex

25
Q

What happens after 10 days from having the inf?

A

Specific T cells are produced And activate macrophages

Macrophages take bacteria and present them to T cells

26
Q

What does the granulomas contain?

A

Mixture of necrotic tissue and dead macrophages at the center —> CASEATION

27
Q

What does macrophages do when they have lots of bacilli?

A

They kill themselves —> give rise for other more competent cells to take these bacilli تكملة مع تفريغ

28
Q

Slide 7 up

A

تفريغ

29
Q

What happens when dormant bacilli are reactivated ?

A

Post 1ry disease

30
Q

What is military TB or disseminated TB?

A

A. Spreading 1ry inf of TB outside the lungs where it was there 1ry

B. One of the infective foci progresses and gives rise to :

  1. Meningitis
  2. Pleurisy
  3. Kidney disease
  4. May reach bones And joints
31
Q

When does the person become tuberculin +?

A

6 to 8 weeks after initial infection

32
Q

What is post 1ry TB?

A

A. Happens after months or years

B. Deactivation of dormant foci OR exogenous re-infection

C. Same process of granuloma but:

  1. More tissue destruction
  2. Formation of large areas of caseation

D. Spread of the lesions to all parts of the lungs, respiratory tract, and intestine

E. Affects the face and neck

33
Q

When I’s deactivation of TB likely ?

A
  1. AIDS

B. Immunocompromised

34
Q

What is the treatment of TB ?

A

Multiple drug therapy

35
Q

Where is M.bovis ?

A

Commonly found in cattle

Can cause disease in people ( < 2% of total no. Of TB disease in humans ):

  1. by eating or drinking contaminated unpasteurized dairy products
  2. from direct contact with a wounded animal during slaughter or hunting
  3. by inhaling the bacteria in air exhaled by animals infected with M. bovis
36
Q

Slide 9 down

A

BCG تفريغ

37
Q

What are the characteristics of M.leprae?

A
  1. Not cultivated in vitro —> so you need experimental animals to culture
  2. Principal target cell is Schwann cells —> nerve damage —> resp for main clinical features of LEPROSY:
    A. Anaesthesia
    B.muscle paralysis
    ( paralysis + weakness like C.botulinum opposite to C.tetani )
    —> if the disease progresses —> clinical manifestations depend on the immune sys of the host
38
Q

What is the immunological spectrum ?

A

Ranges from hyper reactive tubercoloid (TT) leprosy TO anergic lepromatos (LL)

At TT:

  1. small no of localized skin lesions
  2. small number of bacilli
  3. Inappropriate intense granulomas damaging major nerve trunks.

At LL:

  1. numerous skin lesions
  2. huge numbers of bacilli
  3. No histologic evidence of immune response.

3 types:

  1. Borderline tuberculoid (BT)
  2. mid-borderline tuberculoid (BB)
  3. borderline lepromatous (BL).
39
Q

What happens in tuberculoid leprosy?

A

DTH may cause severe and permanent nerve damage

40
Q

What is the treatment of M.leprae ?

A

Surgery to:

  1. correct deformities
  2. Prevent blindness
  3. treatment with anti-inflammatory drugs.
41
Q

What are the environmental myco bacteria?

A

They are atypical mycobacteria with 2 kinds:

  1. Pigment producers —> photochromogens
  2. Non-pigment producers —> nonphotochromogens
42
Q

Give examples on atypical mycobacteria ?

A
  1. M. kansasii:
    Photochromogen —> orange
    Produces pulmonary and systemic disease in patients with impaired immune responses.
2. M. avium-intracellulare complex: 
Little pigment
Occur in soil
Infect birds
May cause infections in human and in AIDS patients.
  1. M. marinum:
    NO pigment.
    Occurs in water.
    Can cause superficial skin lesions.
  2. M. fortuitum-chelonei complex (non-pigment producers )
    NO pigment
    In soil and water
    can cause disease in human in rare cases.

Pathophysiology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions