Microbiology 13: Mycobacterial Diseases Flashcards

1
Q

Which organism is used in the BCG vaccine ?

A

Mycobacterium. Bovis

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2
Q

Describe Mycobacterium as an organism ?

A
Non-motile 
Rod shaped
Waxy cell wall
Slow-growing
Acid alcohol fast
gram +ve
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3
Q

Name 2 stains that pick up mycobacterium ?

A

auramine

Ziehl neelson

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4
Q

Name the slow growing NTM that causes swimming pool granuloma ?

A

Mycobacterium Marinum

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5
Q

Which slow growing NTM causes Buruli ulcers ?

A

Mycobacterium Ulcerans

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6
Q

What are some risk factors for NTM infections ?

A

Age
Underlying lung disease- CF, Bronchiectasis, COPD
Immunocompromised

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7
Q

What are the 2 types of mycobacterium leprae?

A

Paucibacillary tuberculoid

Multibacillary lepromatous

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8
Q

What are the main differences between Paucibacillary tuberculoid
And Multibacillary lepromatous ?

A

Paucibacillary tuberculoid

  • Few skin lesions
  • robust Th1 cell response

Multibacillary lepromatous

  • abundance of bacilli
  • multiple skin lesions
  • Poor Th2 mediated cell response
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9
Q

What is the primary TB granuloma in the lungs called ?

A

Ghon focus

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10
Q

Which allergic reaction can be seen with primary TB ?

A

Erythema nodosum

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11
Q

What is TB infection of the spine called ?

A

Pott’s disease

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12
Q

What is Scrofula ?

A

Lymphadenitis due to TB, usually affecting the cervical lymph nodes.

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13
Q

How can you test for TB in children ?

A

Gastric aspirate- children swallow their sputum

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14
Q

which 2 tests are used to screen for TB ?

A

Tuberculin skin test

IGRA (interferon gamma release assay)

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15
Q

What are the first line medications to treat TB ?

A

RIPE

Rifampicin
Isoniazid
Pyrazinamide
Ethambutol

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16
Q

Which TB drug causes bright orange secretions ?

A

Rifampicin

17
Q

What is the treatment schedule for pulmonary TB ?

A
  • 6 months of Rifampicin and Isoniazid

- Pyrazinamide and Ethambutol for the first 2 months then stop

18
Q

3 groups of tuberculosis mycobacteria

A

mycobacterium tuberculosis complex
mycobacterium avium complex
mycobacterium abscessus complex

19
Q

features of non-tuberculous mycobacteria

A

atypical
resistant to the usual anti-TB therapy
slow growing = mycobacterium avium intracellular, mycobacterium marinum, mycobacterium ulcerans
rapid growing = m. abscessus, chelonae, fortuitum

20
Q

what are the 2 types of mycobacterium leprae

A

pucibacillary tuberculoid - few skin lesions, robust T cell response
multibacillary lepromatous - abundance of bacilli, multiple skin lesions, poor T cell response

21
Q

stages of TB infection

A

primary TB - usually asymptomatic
latent TB
reactivation of TB (>5yrs after initial infection), RF = immunosuppression, chronic alcohol excess, malnutrition, ageing

22
Q

what does pulmonary TB cause

A

caseating granulomatas

found in upper lung parenchyma and mediastinal LN

23
Q

what parts of the body are affected by extra-pulmonary TB

A

lymphadenitis
GI - swallowing of tubercules
peritoneal - ascitic or adhesive
genitourinary - slow progression to renal disease
bone + joint - haematogenous spread, spine (ports)
military TB

24
Q

TB investigations

A
CXR 
sputum x3
bronchoscopy 
stains for acid-fast bacilli 
tuberculin skin test 
NAAT 
culture = gold standard, takes up to 6 weeks
25
Q

what is the tuberculin skin test

A

looks for previous exposure to mycobacteria
2 units of tuberculin injected intradermaly
delayed-type hypersensitivity reaction

26
Q

side effects fo RIPE

A

rifampicin - orange secretions
isoniazid - peripheral neuropathy, hepatotoxicty
pyrazinamide - hepatotoxicity
ethambutol - visual disturbance

27
Q

what is given in extremely drug resistant TB

A

quinolones + aminoglycosides + para-aminosalicyclic acid + cycloserine + ethionamide

28
Q

what is more likley to occur in HIV and TB

A

more likely to have extra-pulmonary manifestations

smear microscopy and culture is less sensitive