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Microbiology > M20- Fungi- candida > Flashcards

M20- Fungi- candida Flashcards

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Biology 101 flashcards
1
Q

Describe fungi.

A
  • Eukaryotes (nucleus, organelles, etc)
  • Ubiquitous (saprophytic or parasitic)
  • > 200 pathogenic species
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2
Q

what characteristics vary in fungi?

A

– propagation may be sexual or asexual (meiosis/mitosis)
– unicellular or filamentous vegetative structures
– Budding, binary fission etc
– surrounded by a chitin cell wall

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3
Q

what does not work on eukaryotes?

A

antibodies

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4
Q

what are the 4 genres of fungi responsible for 90% of deaths?

A
  • Candida
  • Crytpococcus
  • Apergillus
  • Pneumocystis
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5
Q

what are common fungi conditions?

A
  • Athletes foot
  • Ringworm
  • Vulvovaginal candidiasis
  • Aspergillosis
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6
Q

what are two forms of fungi?

A
  • dimorphic

- polymorphic

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7
Q

what is yeast?

A

single oval cells often reproduce by budding

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8
Q

what is mould?

A

multicellular and composed of tubules or filaments called hyphae

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9
Q

What is the name for a mass of hyphae?

A

mycelium

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10
Q

what is carriage rate of candida?

A

35%

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11
Q

what is the commonest fungi found in the mouth?

A

Candida species

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12
Q

What is the reservoir for candida?

A

dorsal of the tongue

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13
Q

what are two main species of candida?

A
  • C. albicans

- C. glabrata

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14
Q

how is Candida albicans found?

A

spherical or oval budding yeast :

  • single cells or blastospores
  • Pseudohyphae and true hyphae
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15
Q

what does Candida albicans form round?

A

thick-walled resting structures

-chlamydospores

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16
Q

where does Candida albicans colonise?

A
  • Mouth
  • GI tract
  • Skin
  • Female genital tract
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17
Q

what is pseudohyphae?

A

nuclei separated and small perforation in cell walls

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18
Q

what is true hyphae?

A

no cross wall and is more susceptible to fragmentation

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19
Q

what are the types of superficial candidosis (pseudomembranous candidiasis PMC)?

A 
Mucosal infection (thrush)
Other skin infections:
-Interigo (pustules that rupture )
-Nappy rash -originating from GI tract 
-Paronychia -infection of nails
-HIV infection - Candida infection frequent
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20
Q

what are superficial candida infections?

A

effect mainly the skin and epithelial surfaces

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21
Q

what are mucocutaneous candida infections?

A

involve both the skin and the underlying mucosa

22
Q

Describe chronic mucocutaneous candidosis?

A

• Rare, but difficult to treat
• Persistent infection of mouth &/or mucosal
surfaces
• Skin and mucosa are involved
• Usually a consequence of damaged host immune system or metabolism
• CMC sometimes seen with T-cell deficiency
• Systemic antifungal therapy required

23
Q

what are systemic or deep infections?

A

occur in major organs following Candidaemia (i.e blood infection)

24
Q

what happens if systemic or deep infections go untreated?

A

Untreated disseminated disease is fatal

25
Q

what is the initial infection of systemic candidosis?

A

– Lower respiratory tract &/or urinary tract
– Candidaemia, (Candida in the blood)
– fungi migrate;
• endocardium, meninges, bones, kidneys or eyes

26
Q

what are risk factors of systemic candidosis?

A

– seriously ill patients

– heart surgery, long term immunosuppression or drug therapy

27
Q

what are the causes of erythematous candidiasis?

A 
•  Denture Wearing –  Most common
•  Prolonged Drug Therapy 
–  Antibiotics
–  Topical steroids 
•  Persistent PMC
–  Underlying problem 
•  AIDS Patients
28
Q

what is identification of Candida species aided by?

A

chromogenic media

-chemicals in broth produce different coloured colonies for different species

29
Q

Discuss the presentation of erythematous and denture related candidosis.

A

red swollen inflamed mucosae

-usually limited to area of an upper denture

30
Q

Describe the cause of erythematous and antibiotic sore mouth.

A

– Suppression of normal oral bacterial flora
– overgrowth by C.albicans
– usually broad spectrum
antibiotics
– especially tetracycline and consequent mucosa of tongue and cheeks becomes thin, inflamed and atrophic

31
Q

what is the treatment for Erythematous & Denture related candidosis?

A

– topical antifungal agents,
– cleaning denture
– removing denture at night

32
Q

what is angular cheilitis?

A

Erythema and fissures in the angulum oris

– Overgrowth of C. albicans at the angle of the mouth

33
Q

where is angular cheilitis usually seen in?

A

– denture wearers,
– vitamin deficiencies
• iron and vitamin B12

34
Q

when can superinfection occur (angular cheilitis)?

A

Superinfection with S.aureus other species may also occur

35
Q

how is angular cheilitis treated?

A

– antifungal agent

– resolving underlying problem

36
Q

Describe chronic hyper plastic candidosis (candidal leukoplakia)

A 
•  Individual lesions
•  White patches cannot be
rubbed off
•  Red/white speckled patches can occur
•  Surface parakertainized & hyperplastic
•  5-11% can become malignant
•  C. albicans role not clear
37
Q

what are the risk factors of chronic hyper plastic candidosis?

A

– Smoking,

– folic acid or Iron deficiency

38
Q

what are the risk factors of candidal leukoplakia?

A
  • Denture Hygiene (Trauma, chronic irritation)
  • Medications
  • Immunosuppression
  • Xerostomia
  • Endocrine disfunction
  • Moisture/Poor hygiene
  • Smoking (co-factor)
  • Blood Diseases
39
Q

Describe the adherence virulence factor of C. albicans.

A

– Hyphal-form more adhesive (acrylic)
– Hydrophobic surface
– Specific Adhesins
– Fibrillar mannoprotein

40
Q

Describe the host defences/damage.

A

-Proteinases (SAPs)
– Phospholipase
– Concentrated at Hyphal tip

41
Q

what is the change in shape of yeast to pseudohyphae to hyphae linked to?

A

disease process

42
Q

Name 2 common anti fungal agents.

A

Polyenes - bind ergosterol in membrane

Azoles - interfere with ergosterol production

43
Q

what anti fungal agent has anticandidal activity ?

A

Chlorohexidine

44
Q

what is the role of polyenes (anti fungal agent)?

A

integration into cell membrane.

Example: Nystatin

45
Q

what is the role of azoles (anti fungal agents)?

A

interruption of sterol biosynthesis ( cell and mitochondria membranes)
Example: Miconazole and fluconazole

46
Q

Describe the action of Nystatin (polyenes).

A
  • Effective against all Candida species
  • Resistance rare
  • Binds to ergosterol in fungal lipid membrane – makes membrane leaky
  • Topic application only
47
Q

what is miconazole an inhibitor of?

A

ergosterol formation

48
Q

how is miconazole used systemically?

A 
–  Miconazoletaken
absorbed by GI tract
–  Fluconazolesecretedin saliva
–  C.albicans
–  Candidaspeciesoften
resistant
49
Q

When are patients resistant to miconazole?

A

long term HIV therapy

50
Q

what anti fungal resistance is most common?

A

azoles

51
Q

Give example of azole resistance.

A
  • Candida glabrata (azalea resistance mechanism)
  • Candida krusei (intrinsic resistance to azoles)
  • Candida auris (intrinsic resistnace)

Microbiology (30 decks)

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