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A-Level Flashcards on various topics > Microbio- mycobacterial infections > Flashcards

Microbio- mycobacterial infections Flashcards

1
Q

2 broad groups of mycobacteria - phylogenetically and clinically

A

Clinically: Mycobacterium tuberculosis + Non-tuberculous mycobacteria

Phylogenetically - slow growing + rapid growing

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2
Q

Mycobacteria - morphology? do they grow fast?

A

Non-motile, rod shaped

Slow growing compared to other bacteria

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3
Q

Stains for Mycobacteria

A

Ziehl- Neelsen

Auramine

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4
Q

NTM - how do people get infected i.e. where do they come from?

A

Found in water and soil

No person-to person transmission

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5
Q

Name 3 slow growing NTM

A

M. avian intracellular

M. marinum

M. ulcerans

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6
Q

NTM often acquired from swimming pools

A

M. marinum

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7
Q

Which NTM results in huge chronic painless ulcers

A

M. ulcerans

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8
Q

Which NTM is associated with HIV? how does this same organism affect immunocompetent individuals

A

M. Avium

Will affect immunocompetent people if they have pre-existing bronchiectasis/cavities

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9
Q

M. abscessus/chelonae/fortuitum

What type of mycobacteria are these? when are they seen?

A

Rapid growing, in hospital settings

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10
Q

Requirements for diagnosis of NTM?

A

Lung disease AND

1 +VE sputum culture
OR
\+ve BAL
OR
\+ve biopsy w granulomata
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11
Q

Leprosy - name the causative organism

A

Mycobacterium leprae

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12
Q

Which type of leprosy –> limb loss?

A

Paucibacillary tuberculoid

V LITTLE PERSON-PERSON TRANSMISSION

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13
Q

Which type of leprosy is contagious?

A

Multibacillary lepromatous

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14
Q

A 23 year old HEALTHY male is aCLOSE CONTACT of a person with smear positive pulmonary TB, What is his lifetime risk of developing active TB?

A

10%

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15
Q

One person is exposed to TB. What are the 5 possible outcomes

A
  1. Uninfected
  2. Infection is cleared
  3. Contained infection (localised infection)
  4. Active TB
  5. Latent TB (at risk of developing active TB w triggers)
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16
Q
  1. Uninfected
  2. Infection is cleared
  3. Contained infection (localised infection)
  4. Active TB
  5. Latent TB (at risk of developing active TB w triggers)

^who will have a +ve mantoux test?

A

Latent TB

Active TB

17
Q

3 most common forms of MTB

A

M. tuberculosis
M. bovis
M. africanum

18
Q

Which form of TB is associated with contaminated milk

A

M. bovis

19
Q

Why is TB so infectious? how is it transmitted?

A

Particles <10mcM therefore suspended in air and infectious for 30 mins

V low infectious dose

20
Q

How can TB be prevented? Give 3 ways

A
  1. BCG vaccine
  2. -ve pressure isolation
  3. Detection of cases (mantoux)
21
Q

Skin manifestation of TB?

A

Erythema nodosum

22
Q

Wtf is miliary TB

A

Widespread and looks dotty on CXR

Due to haematogenous spred

23
Q

What is post-primary TB? TF?

A

Latent TB that is reactivated approx 5 years later.

EtOH excess, immunosuppression, malnutrition, aging

24
Q

Where are caseating granulomas seen in pulmonary TB?

A

Lung parenchyma
Mediastinal LNs

often upper lobe

25
Q

In extra-pulmonary TB, which LNs tend to be affected?

A

cervical

26
Q

Eggs of extra pulmonary TB?

A 
LNs
Peritoneal --> ascites
GU --> renal disease
Spine (eg Potts)
Miliary 
Meningitis
27
Q

Ix for clinical suspicion of TB

A 
Sputum x 3
Histology
Biopsy
Stain for acid fast bacilli
Culture
NAAT - detecting mutations for MDR
IGRA
Mantoux test
28
Q

Gold standard Ix for TB? how long does it take for results?

A

Culture

Takes up to 6 weeks!

29
Q

what is IGRAs?

is it better than mantoux test?

A

detection of antigen specific IFNgamma production

It doesn’t cross react with BCG vaccine whereas Mantoux does (thus mantoux gives false positive result)

30
Q

Tx of TB

A

RIPE

all drugs for 8 weeks. RI for a further 8 weeks

31
Q

SEs of TB meds

A

Rifampicin - CYP450 inducer
Isoniazid - peripheral neuropathy
Pyrazinamide - hepatotoxicity
Ethambutol - visual disturbance

32
Q

How to improve adherence to TB Tx?

A

Directly or video observed therapy

33
Q

How does MDR arise?

A

Inadequate treatment or spontaneous mutation

34
Q

Risk factors for MDR TB

A

Poor adherence to TB tx
HIV
Known contact

35
Q

How does management of MDR TB differ to non-MDR?

A

Longer regimen

Quinolones, ahminoglycosides,

36
Q

Why is diagnosis of TB so hard in HIV+ patients?

A

Less classical history - more likely extra pulmonary

Smear and mantoux test is more likely to be -ve despite active disease

A-Level Flashcards on various topics (69 decks)

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