Lc 18 Flashcards

1
Q

What distinguishes mycobacteria from mycoplasma?

A

Presence of waxy cell wall

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2
Q

Where are those mycobacterium found?

A

Water, soil, foodstuffs.
Many are opportunistic pathogens in humans

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3
Q

What are some important determinants of disease presence and severity for all of disease from mycobacteria?

A

Host susceptibility

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4
Q

Are mycobacterium gram negative or gram positive?

A

Neither, but slightly positive when stained

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5
Q

What are composed of in their cell wall?

A

60% mycolc acids. ( waxy coats), lipoarabinomannan

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6
Q

Mycobacteria are acid fastness. What does it mean?

A

Resists destaining( resistance to decolorization) by acid or ethanol

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7
Q

What does the waxy cell wall do?

A

It is very resistant to drying

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8
Q

Even if you stain the bug(mycobacteria), you won’t see any color but purple. True or false?

A

True.

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9
Q

How do you divide mycobacteria into two distinct types?

A

Slow growing and fast growing

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10
Q

Explain slow growing and fast growing.

A

Slow growing :
-M.tuberculosis, M.leprae are examples
- Generation times often 40x E.coli
- forms visible colonies > 7 days

Fast frowing:
- M. abscessus spp
- Forms visible colonies or growth < 7 ays

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11
Q

Explain mycobacteria’s characteristics

A

Aerobic
Nonmotile (except M.marinum)
Difficult to culture in vitro
Difficult to manipulate genetically
Susceptibility to infection is conferred by host characteristics

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12
Q

Mycobacyeria are hard to grow in in vitro and hard to manipulate genetically.
What does that result in?

A

Hard for lab study and diagnosis

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13
Q

What characteristics of slow mycobacteria growth makes them difficult to treat?

A

-less likely to respond to standard antibiotics
-often grows to high densities before immunity develops
- develop resistance to single agents easily

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14
Q

How do we treat mycobacterium?

A

Use multiple drugs

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15
Q

What are the cause of resurgence of mycobacterium?

A

Poverty
Crowding
Malnutrition
Africa-Asia hardest-hit
Multi drugs resistance
HIV/AIDS

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16
Q

HIV impacts TB. How do they do that?

A

They infect T cells

17
Q

AIDS increases susceptibility to to tuberculosis. True or false

A

False. AIDS increases susceptibility to to non tuberculosis disease, especially M. Avium complex

18
Q

Covid also impacts TB. Does poverty impact TB?

A

Yes. Sadly

19
Q

What are the clinical features of TB?

A

Primary : often quite
Immunocompromised - bugs go crazy and disseminated disease can occur

Secondary: reactivation disease .
Immune response(night sweats, fever, weight loss)

20
Q

How do TB get transmitted?

A

Via droplets
—> coughing, talking,sneezing
—> remain in the air for hrs
—> small droplet nuclei can penetrate lung airspaces
—> require prolonged recurrent exposure for infection

21
Q

Explain TB pathogenesis

A

-M. Tb replicate in macrophages, destroying them.
-Blood borne inflammatory cells migrate to infection —> granuloma
-infected macrophages disseminates via lymphatic to lymph nodes

22
Q

Define immunocompetent and immunocompromised

A

Immunocompetent : helathy individ. W good immune systems

Immunocompromised: unhealthy, susceptible individuals, —> often in infants and elderly

23
Q

When does TB get very infectious? Primary or secondary TB?

A

Secondary TB (deactivation)

24
Q

When does latency state happen?

A

Once they have developed immune response..
It splits into two categories :containment, reactivation

25
How do we diagnose TB.
Microscopy, culture, PCR, skin yest(PPD), IFN-r release test
26
What is the most important part of treating TB.
Use multiple drugs Use more than 3 agents for disease (High bacterial burden) Single agent for known exposure, no disease (low bacterial burden)
27
What is the first bacterium identified as causing disease in humans
Leprosy (Hansen’s disease)
28
Can we cultivate leprosy in vitro?
No
29
What are the hosts of leprosy?
Humans and primates Armadillos Eurasian red squirrel
30
How does leprosy get transmitted?
Aerosol Exposure to animals or soils Epidemiology is very difficult
31
We also need multidrug therapy for leprosy. True?
True. Use multi drugs —> lose infection within 3 days