Microbiology 17 - Mycobacterial disease Flashcards

1
Q

How are mycobacteria classified?

A

Based on speed of growth
<7 days = fast
>7 days = slow

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2
Q

Recall 2 examples of slow-growing mycobacteria

A

M bovis

M tuberculosis

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3
Q

What is the key cell wall component of mycobacteria that makes them so different from other bacteria?

A

Long chain fatty (mycolic) acids

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4
Q

Recall 2 stains that can be used to identify mycobacteria

A

Auramine

Ziehl Neelsen

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5
Q

In which patient group is M. avium complex most common?

A

HIV positive

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6
Q

Which type of mycobacterium is associated with cardiothoracic procedures?

A

M. chimera

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7
Q

Which mycobactrium species is known as the “swimming poool granuloma”?

A

M. marinum

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8
Q

How can M. marinum infection present?

A

Skin lesions on hands and arms of fish-owners

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9
Q

What is the main symptoms of M. ulcerans infection?

A

Painless, destructive ulcer

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10
Q

What type of infection do fast-growing mycobacteria tend to cause?

A

Skin and soft tissue infections

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11
Q

How should rapid-growing mycobacteria be treated?

A

Macrolide + additional antibiotics based on susceptibility testing

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12
Q

What is the most severe form of disease that mycobacterium leprae can cause?

A

Multibacillary lepromatous

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13
Q

Recall some strategies for TB prevention

A

Contact tracing and treatment of index case
Screening of those considered at risk
Vaccination
Improvement of living conditions

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14
Q

What is required for diagnosis of TB?

A

3 sputum samples - smear them and culture them, NAAT if possible

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15
Q

What are the 2 possible tests for latent TB?

A

Mantoux test

IGRAS (detection of antigen-specific interferon gamma)

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16
Q

What duration of treatment should be given in CNS TB?

A

12 months

17
Q

What is the standard treatment regimen for M. tuberculosis?

A

2/12 rifampicin, isonoazid, pyrizinamide and ethambutol

4/12 rifampicin and isoniazid

18
Q

What are the main side effects of each of the drugs used to treat M tuberculosis?

A

Rifampicin: orange secretions
Isoniazid: peripheral neuropathy
Pyrizinamide: hepatotoxicity
Ethambutol: visual disturbance

19
Q

How can multi-drug resistant TB be treated?

A

More than 18 months treatment with at least 5 drugs

20
Q

Where does TB infection become latent?

A

Gohn focus/ granuloma

21
Q

What is the name for spinal TB?

A

Pott’s disease

22
Q

Which patients cannot receive the BCG vaccine?

A

Immunosuppressed patients

23
Q

What treatment is used as TB prophylaxis?

A

Isoniazid monotherapy

24
Q

Give some classical features of Leprosy

A

Skin depigmentation
Nodules
Trophic ulcers
Nerve thickening - most disability is due to nerve damage

25
Q

What is the cause of a Buruli ulcer and how does it present?

A

Mycobacterium ulcerans

Painless nodules progressing to ulceration, scarring and contractures