Brainscape's Knowledge GenomeTM

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


See full index

Microbiology > Mycobacteria > Flashcards

Mycobacteria Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Name 2 important mycobacterial species

A

M. tuberculosis

M. leprae

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

What proportion of the worlds popln has TB?

A

1/4-1/3 (ie 25% - 33%)

about 10% of these are having the active disease

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

What is Pott’s disease?

A

TB of the vertebrae

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

What are some of the features seen in leprosy?

A

lepromatous leprosy - patches seen on skin

leonine facies - due to loss of innervation, nose or fingers may fall off

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

Are mycobacteria aerobic or anaerobic and what does this mean in terms of types of infections caused?

A

aerobic - mainly causes lung and skin infections

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

What shape are mycobacteria?

A

bacilli

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

What specific quality of the cell wall do mycobacteria have?

A

high molecular weight lipids

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

What is special about mycobacteria and macrophages?

A

mycobacteria resist phagocytosis and can survive inside macrophages

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

How fast do mycobacteria grow?

A

SLOWLY - doubling time 15-20hrs

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

Why do mycobacteria take a long time to reproduce?

A

as their waxy membrane takes a lot of time and energy to form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are the key components of the lipid cell wall?

A

mycolic acids

lipoarabinomannan

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

If mycobacteria grow slowly, what does that mean for the onset of the disease?

A

has a very slow and insiduous onset

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What difficulties in treatment does slow growth cause?

A

difficult to culture and so diagnosis may take a while - as the commensals would grow faster and completely overgrow the plate
treatment takes a long time, as bacteria are usually targeted for their growth and cell wall production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are Koch’s postulates?

A

infective diseases have these features:
Bacteria should be found in all people with disease.
Bacteria should be isolated from the infected lesions in people with the disease.
A pure culture inoculated into a susceptible person should produce symptoms of the disease.
The same bacteria should be isolated from the intentionally infected individual.

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

What makes mycobacteria resistant to gram stain?

A

high lipid content of cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What stain is used for acid fast bacilli?

A

Ziehl-Neelsen stain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the 3 steps to ZN staining?

A

carbol fuschin primary stain
acid alcohol (AFB - resistant to destaining)
methylene blue counterstain

18
Q

What is the name of the fluorescent stain used for AFB?

A

auramine phenol - is much more sensitive and easier to see the mycobacteria

19
Q

What is a common type of sample taken for TB?

A

sputum

20
Q

describe the ways to grow mycobacteria in culture

A

need to use antibiotics to prevent the growth of other bacteria
fastidious, so need special media such as Lowenstein Jensen (3-8 weeks)
can alternatively use liquid broth (1-3 weeks)
and then the mycobacteria are detected by MGIT

21
Q

What is culture followed up by?

A

speciation and testing for drug resistance

22
Q

Describe the nucleic acid detection of mycobacteria

A

PCR is used and is very sensitive

can even detect rifampicin resistance with fluorescence

23
Q

What die the Cd 4 T cell generate and how does this help in the immune response to mycobacteria?

A

interferon gamma

makes other macrophages more effective at killing mycobacteria

24
Q

What is a key histological feature of mycobacterial disease?

A

granuloma

25
Q

How long does it take for T cell responses to form against TB?

A

3-9 weeks

26
Q

What is the tuberculin skin test testing for?

A

memory T cells to TB

27
Q

What does the interferon gamma release assay involve?

A

using the white blood cells of the pt and exposing them to antigen from TB and seeing whether INF gamma is produced

28
Q

Why do we get different types of leprosy?

A

due to the immune response of the individual against leprosy - either a very large immune response that damages the tissues or to little immune response that the bacilli damage the tissues

29
Q

what difficulties are there in treating mycobacterial infections?

A
  • slow replicating bacteria so need prolonged treatment
  • different poplns in different parts of the body
  • drug resistance so large combinations of drugs used
  • compliance is important
30
Q

What is the standard therapy for TB?

A 
isoniazid +
rifampicin +
pyrazinamide +
ethambutol for 2 months and then:
rifampicin + isoniazid for the next 4 months
31
Q

give examples of drugs that may be used if there is resistance

A

streptomycin
cycloserine
capreomycin
fluoroquinilones

32
Q

what side effects are there from anti-tuberculous drugs?

A

hepatotoxicity
peripheral neuropathy
optic neuritis

33
Q

What two factors of the apex of the lung make it favourable for the growth of TB?

A

more air

less blood supply (so less WBCs)

34
Q

Will anything abnormal be seen on X-ray with latent TB?

A

no

35
Q

IS latent TB detectable in a tuberculin prick test?

A

yes - as cell mediated response persists but the primary infection is contained

36
Q

What is the name given to TB that develops immediately following the primary disease?

A

post-primary infection

37
Q

What is a key feature of primary tuberculosis?

A

caseous necrosis resulting in cavities in the lung

38
Q

Where can TB spread to?

A 
brain - meningitis
all over - miliary TB 
bone and joint TB
kidneys - genitourinary TB 
pleura - pleural TB
TB peritonitis
39
Q

What type of T cell response is the the major immune response to TB?

A

Th1 which produce interferon gamma and TNF alpha

40
Q

Who is at increased risk of TB reactivation?

A

infants, young adults and elderly
malnourished
those with a high intensity of exposure
the immunosuppressed

Microbiology (12 decks)

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