Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MICRO ADYA > Microbiology 16 - Fungal infections > Flashcards

Microbiology 16 - Fungal infections Flashcards

1
Q

What is the main conponent of fungal cell walls?

A

Chitin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the main component of fungal cell membranes?

A

Ergosterol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What type of RNA do fungi contain?

A

80S

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are yeasts? How do they reproduce?

A

Single celled organisms

Reproduce by budding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Recall 3 examples of yeasts that are clinically important

A

Candida
Cryptococcus
PCP

CCP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are moulds?

A

Multicellular hyphae

Reproduce by branching and extension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which fungus is dimorphic (can change between yeast and moulds)?

A

histoplasma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Give 3 examples of moulds that are clinically important

A

MAD

mucormyocsis

aspergillus

dermatophytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the most common cause of fungal infections in humans?

A

Candida

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is candida? What patterns of infection does it cause?

A

Yeast

Commonest cause of fungal infections in humans

Can cause acute, subacute, chronic or episodic infection

Can be superficial or invasive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Recall the empiric treatment for oral, vulvovaginal, oesophageal and localised cutaneous candida infection

A

Oral candidasis: TOPICAL NYSTATIN

Localised cutaneous: TOPICAL CLOTRIAZMOLE

Vulvovaginal: TOPICAL CLOTRIMAZOLE or if severe - ORAL FLUCONAZOLE

Oesohpageal: TOPICAL CLOTRIMAZOLE or if severe - ORAL FLUCONAZOLE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the risk factors for candidamiea?

A
  • Malignancies, esp haematological

– Burns patients

– Complicated post-op courses (eg Tx or GIT Sx)

– Long lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Examples of superficial candida infections

A

Oral candidasis

Oesophageal candidasis

Cutaneous - localised or generalised

Vulvovaginal candidasis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Recall the principles of candidaemia management

A
  1. Look for source and signs of dissemination:
    - Imaging
    - Serology for B-D-glucan
    - echo (for endocarditis)/fundoscopy (for eye infection)
  2. Antifungals for at least 2/52 from date of first negative blood culture - repeat BCs every 48 hours (echinocandin until sensitivities identified) 3. remove any lines/prosthetic material

cbd - candida beta glucan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Examples of invasive candida infections and specific treatments

A

1. Urinary tract (vulvogaintis or catheter): fluconazole

2. CNS: ambisome (amphotericin B) or voriconazole

3. Bone and joint: ambisome (amphotericin B) or voriconazole

4. Endocarditis (abnormal or prosthetic valves): ambisome (amphotericin B) or voriconazole

5. Intra-abdominal: echinocandin or fluconazole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How is cryptococcus spread?

A

Aerosolised fungus is inhaled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Morphology of cryptococcus

A

Encapsulated yeast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Life cycle of cryptococcus

A

C. neoformans: associated with pigeon droppings

C. gatii: associated with eucalyptus trees

–>inhalation of ubiquitous spores can disseminate in immunocompromised people, has a prediliction for the CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Recall the different types of cryptococcus, and which of these infect immunocompetent vs immunocompromised hosts

A

Serotypes A and D = cryptococcus neoformans (immunocompromised hosts)

*NB: T cell deficiency makes you particularly susceptible (eg AIDS, post transplant immunosuppression)

Serotypes B and C = cryptococcus gatti (immunocompetent hosts)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which type of cryptococcus can cause meningitis?

A

Cryptococcus gatti

In apparently immunocomptenet people

Especially in Australia and SE asia; tropical latitudes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

WHich organ system does cryptococcus have a predlicition for?

A

Central nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What ink can be used to stain for cryptococcus?

What is the gold standard investigation?

A

India Ink - stains everything black except for the capsule

*appears as an encapsulated yeast

Gold standard: enzyme immunoassay for antigens in capsule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is c. gatii resistant to?

A

Amphotericin B (ambisome)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is C. neoformans resistant to?

A

echinocandins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How should cryptococcus infection be managed?

A
  • *1. Induction:** 2/52 of amphotericin B +/- flucytosine
  • *2. Consolidation:** 8/52 of high dose fluconazole
  • *3. Maintenance:** 1 year low-dose fluconazole

+ LP for symptomatic relief (as patients tend to have high opening pressure)

IF MILD PULMONARY INFECTION - fluoconazole alone

**Path guide: amphotericin B and flucytosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Why is pneumocystis jirovecii an unusual fungus?

A

No ergosterol in cell membrane

^so antifungals targeting cell membrane will not work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the typical history for PCP pneumonia?

Typical CXR feature?

Diagnosis of PCP?

Treatment?

A

Desaturating on exertion

CXR: bat winging

Diagnosis: usually immunofluorescence, but can also be detected on silver stain

Treatment: cotrimxazole (+ steroids if hypoxia is present)

28
Q

Main species of aspergillus that is clinically important

How is it transmitted?

A

Aspergillus fumigatus

Airborne transmission

29
Q

Clinical spectrum of aspergillus disease?

A
  1. Aspergilloma
  2. ABPA
  3. Invasive aspergillosis - mostly immunocompromised patients
30
Q

How does ABPA present?

A
  • Chronic wheeze
  • Allergy
  • Bronchiectasis
  • Eosinophilia
31
Q

How does aspergilloma present?

A

Colonises pre-formed cavities eg those formed by TB

*so treated pulmonary TB may be in the history

32
Q

What assay is used for asperigillus diagnosis and why?

A

Galactomannan assay - because aspergillus contains this in the cell wall

33
Q

What is a galactomannan assay used for?

A

Aspergillosis diagnosis

34
Q

How does aspergillus appear under the microscope?

A

Can see hyphae

But can’t identify the type based on hyphae. Need to analyse the spores produced by the fungi.

35
Q

Tx of aspergillus infection

A

Ambisome or voriconazole

Fluconazole has POOR ACTIVITY AGAINST MOULDS!!

36
Q

What are dermatophytes?

A

Moulds

They invade dead keratin

Spread by contamination with desquamated skin scales

37
Q

Examples of dermatophytes

A

trichophyton rubrum

pitiriasis veriscolor

38
Q

Types of tinea - and which organism causes them?

A

Pedis: foot (athlete’s foot)

Capitis: head

Corposis: body (AKA RINGWORM)

Cruris: groin

Caused by TRYCHOPHYTON

39
Q

Pityriasis versicolor:

  • cauasative agent
  • features
  • diagnosis
  • management
A

Caused by: Malassezia furfur

  • Characterised by discolouration of the skin

hypopigmentation (in patients with dark skin tones)

hyperpigmentation (in patients with pale skin

  • diagnosis: “sphaghetti with meatballs” appearance with potassium hydroxide, or orange fluorescence under wood’s lamp
  • management: topical clotrimazole, ketoconazole
40
Q

How is tinea diagnosed?

A

Often clinically, but can be confirmed via skin scrapings for MC&S

41
Q

What are the clinical features of mucormycoses?

A

Orbital/facial cellulitis with discharge of black pus from nose/ palate

Can also spread to brain

*can spread via inhalation of spores or primary colonisation of skin

* immunocompromised patients, poorly controlled diabetics

42
Q

How are mycormycoses managed?

A

Surgical emergency- debridement of necrotic tissue

LONG duration of ambisone (amphotericin B)

43
Q

Recall 4 classes of antifungal

A

Azoles
Polyenes
Echinocandins
Pyrimidine analogues

44
Q

Recall the side effect profile of each class of antifungal

A

Azoles - abnormal LFTs
PolyeNes - Nephrotoxicity
Echinocandins - relatively innocuous - whci his good bc this is the one you use broad spectrum if you dno’t know the organism causing candidaemia
Pyrimidine analogues - blood disorders

45
Q

What is the mechanism of action of azoles?

A

Inhibit ergosterol synthesis

46
Q

What is the mechanism of action of polyenes?

A

Bind sterols in membranes to create leakage of electrolytes

*so targets ergosterol

47
Q

Give 2 examples of polyene medications

A

Amphotericin B
Nystatin

48
Q

Which 2 types of fungus are echinocandins particularly useful for?

A

Candida (rmb it is used for candidaemia until cultures are back)
Aspergillus

*so one yeast (candida) and one mould (aspergillus)

49
Q

What class of antifungal is flucytosine?

A

Pyrimidine analogue

50
Q

Example of echinocandin?

A

Capsofungin

51
Q

How to diagnose superficial fungal infections?

A

Wood’s lamp

52
Q
A
53
Q

Which fungi cause superficial infections?

A

Tinea: Dermatophyte e.g. Tricophyton rubrum: Ringworm, Athlete’s foot o Pityriasis: Malassezia globosa/furfur : seborrhoeic dermatitis, T. versicolor

54
Q

(depigmentation in those with darker skin

A

Pityriasis versicolor

55
Q

Which fungi cause deep seated infection?

A

Candida

Aspiergillus

Cryptococcus

56
Q

Dx of candida

A

Culture, Mannan, Antibodies

57
Q

Summary of treatment of candida infections

A

a) fluconzaole: canddia albicans
b) amphotericin-B: invasive disease

58
Q

Dx of aspergillus

A

ELISA, PCR, β-Glucan test, grows on Czapek dox agar

59
Q

Tx of aspergillus

A

Voriconazole

(AV)

60
Q

Polyene

A

eg amphotericin

target: cell membrane integrity
indication: yeast

61
Q

azole antifungals

A

eg fluconazole

target- cell membrane syntehiss

indication- yeast

62
Q

terbinafine

A

target: cell membrane
indication: mould (specifically- dermatophytes)

**need to order LFTs before starting

63
Q

flucytosine

A

target: DNA synthesis

64
Q

echinocandin

A

eg capsofungin

target: cell wall
indication: yeast (less toxic side effects)

65
Q

WHat does coccioides cause?

A

systemic infection - valley fever

fever, cough, lethargy etc.

*from arizona, utah etc (think valleys)

66
Q

what fungus causes mucormycosis?

A

rhizopum species

MICRO ADYA (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions