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CELL MICRO S1 > Myobacteria > Flashcards

Myobacteria Flashcards

1
Q

describe mycobacteria

A
  • unicellular and branched rods
  • G+ve
  • complex cell wall (cont sugars, proteins and LOT OF LIPID)
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2
Q

how can mycobacteria be stained and identified?

A 
Acid fast staining-Ziehl Neelson stain:
-stain carbol fuchsin
-destain acid alcohol
-counterstain methylene blue 
mycobacteria= RED (everything else=blue)
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3
Q

what is found in cell walls of Mycobacteria?

A

mycolic acid (protective, waxy coat) outside peptidoglycan layer

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4
Q

what are the two groups of Mycobacteria?

which group is pathogenic?

A

1) fast growers (1-2 days on plates)

2) slow growers (several weeks)- PATHOGENIC group

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5
Q

M.bovis causes?

A

bovine TB

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6
Q

M.avium is what type of pathogen?

where is it found?

A
  • opportunistic pathogen

- ub in env

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7
Q

M.paratuberculosis affects what?

A

ruminants

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8
Q

M.ulcerans affects who?

causes what?

A

humans

causes ulcers

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9
Q

M.leprae affects who?

A

humans

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10
Q

M.marinum affects who?

A

fish, frogs and humans

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11
Q

significance of TB

A
  • global emergency
  • 35000 deaths a week
  • high incidence in HIV individuals
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12
Q

outcomes after TB exposure

A

1) EXPOSURE, NO INF
- TB cleared before it gets past INNATE immune defences
2) EXPOSURE, INF, NEVER DISEASE
- if immunocompetent, 90% DON’T get disease
3) EXPOSURE, INF, DISEASE, +/- DEATH
- asymptomatic latent period

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13
Q

how do you test for TB?

A

Heaf/Mantoux test- antigen is placed on skin, punch is used to punch it into skin
may form INFLAMMATORY response

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14
Q

how does TB exit the host?

A

by causing TB infection/disease

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15
Q

describe the pathogenesis of TB

A
  • aerosol travels to alveoli of lungs
  • M.tuberculosis engulfed by alveolar macrophages
  • if activated due to an acquired immune response host clears bacteria or contains infection
  • if unactivated (child or immunocompromised), bac survive and replicate in macrophages—> attracts more PMN & T cells—> damage tissue, form granulomatous tubercle
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16
Q

what can be used to diagnose TB?

A

1) X ray
2) microscopy of sputum looking for acid fast rods
3) culture sputum samples(media con egg or oleic acid or albumin)
4) PCR

17
Q

what happens when the granuloma (tubercle) grows?

A

it eventually breaks into the airway of lung, is coughed up and O bacteria are released-
TRANSMISSION

18
Q

how is the granuloma formation capable of stopping TB progressing?

A

may contain the infection and stop TB development BUT can also aid transmission (granuloma coughed up—>transmitted)

19
Q

what HOST FACTORS determine how someone responds to TB infection?

A
  • HIV status
  • immunodeficiency
  • genetic immunodeficiency
  • substance abuse
  • malnutrition
20
Q

what BACTERIAL FACTORS determine how someone responds to TB infection?

A
  • small differences in STRAIN VIRULENCE
21
Q

TB symptoms?

A
  • fever
  • weight loss
  • weakness
  • PERSISTENT COUGH (due to inflammatory response)
22
Q

where can TB spread (15% of cases)?

A

CNS, lymphatic system, genitourinary systems, bones etc

23
Q

TB prevention?

A

BCG Vaccine

24
Q

TB treatment?

A

MULTI DRUG AB treatment (~6 months)

4 main ABs are 1st line

25
Q

how effective is the BGC vaccine?

A

efficacy varies by geographic location and population

  • works well in children
  • protects against leprosy
26
Q

describe AB resistance for TB

A

resistance = inc common

some strains are resistant to ALL 4 FRONTLINE DRUGS called EXTENSIVELY DRUG RESISTANT TB

27
Q

what causes resistance in TB?

A
  • failure to take all medications

- failure to be provided w/ steady supply of medication

28
Q

what causes leprosy?

A

M. leprae

29
Q

how can we grow M.leprae?

A

cannot be cultivatable, but can be grwon in armadillos, squirrel ears & mouse footpads

30
Q

what type of parasite is it?

A

intracellular, grows in macrophages and Schwann cells (—> nerve damage)

31
Q

how is M.leprae transmitted?

A
  • little known
  • most who come into contact are NOT infected
  • those w/ leprosy have high counts in nasal discharge
32
Q

what % of infected individuals get the leprosy?

A

5%

33
Q

what are the 2 clinical manifestations of leprosy?

A

1) TUBERCULOID
-few bacilli in tissue, mild disease, few skin lesions
Host response: strong immune response, low antibody, tuberculoid GRANULOMA forms to CONTAIN the infection

2) LEPROMATOUS
- severe, huge nos of bacilli in tissue, multiple lesions, skin nodules packed with bacteria. Nerve damage, loss of extremities, DEATH
Host response: poor immune response, high antibody, FOAM CELL GRANULOMA

34
Q

how is leprosy prevented?

A

BCG vaccine

35
Q

how is leprosy treated?

A

ABs (Dapsone), treatment may be for life

36
Q

describe resistance to M.leprae

A

increasing O need multi drug therapy

CELL MICRO S1 (16 decks)

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