Eukaryotes (nucleus, organelles, etc) Ubiquitous (saprophytic or parasitic) > 200 pathogenic species

M20- Fungi- candida Flashcards by Emma Williams

Describe fungi.

Eukaryotes (nucleus, organelles, etc)
Ubiquitous (saprophytic or parasitic)
> 200 pathogenic species

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what characteristics vary in fungi?

– 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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what does not work on eukaryotes?

antibodies

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

Candida
Crytpococcus
Apergillus
Pneumocystis

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what are common fungi conditions?

Athletes foot
Ringworm
Vulvovaginal candidiasis
Aspergillosis

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what are two forms of fungi?

dimorphic

- polymorphic

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what is yeast?

single oval cells often reproduce by budding

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what is mould?

multicellular and composed of tubules or filaments called hyphae

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What is the name for a mass of hyphae?

mycelium

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what is carriage rate of candida?

35%

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what is the commonest fungi found in the mouth?

Candida species

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What is the reservoir for candida?

dorsal of the tongue

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what are two main species of candida?

C. albicans

- C. glabrata

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how is Candida albicans found?

spherical or oval budding yeast :

single cells or blastospores
Pseudohyphae and true hyphae

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what does Candida albicans form round?

thick-walled resting structures

-chlamydospores

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where does Candida albicans colonise?

Mouth
GI tract
Skin
Female genital tract

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what is pseudohyphae?

nuclei separated and small perforation in cell walls

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what is true hyphae?

no cross wall and is more susceptible to fragmentation

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

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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what are superficial candida infections?

effect mainly the skin and epithelial surfaces

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what are mucocutaneous candida infections?

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involve both the skin and the underlying mucosa

Describe chronic mucocutaneous candidosis?

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• 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

what are systemic or deep infections?

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

what happens if systemic or deep infections go untreated?

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Untreated disseminated disease is fatal

what is the initial infection of systemic candidosis?

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

what are risk factors of systemic candidosis?

– seriously ill patients | – heart surgery, long term immunosuppression or drug therapy

what are the causes of erythematous candidiasis?

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

what is identification of Candida species aided by?

chromogenic media | -chemicals in broth produce different coloured colonies for different species

Discuss the presentation of erythematous and denture related candidosis.

red swollen inflamed mucosae | -usually limited to area of an upper denture

Describe the cause of erythematous and antibiotic sore mouth.

– 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

what is the treatment for Erythematous & Denture related candidosis?

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

what is angular cheilitis?

Erythema and fissures in the angulum oris | – Overgrowth of C. albicans at the angle of the mouth

where is angular cheilitis usually seen in?

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

when can superinfection occur (angular cheilitis)?

Superinfection with S.aureus other species may also occur

how is angular cheilitis treated?

– antifungal agent | – resolving underlying problem

Describe chronic hyper plastic candidosis (candidal leukoplakia)

``` • 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 ```

what are the risk factors of chronic hyper plastic candidosis?

– Smoking, | – folic acid or Iron deficiency

what are the risk factors of candidal leukoplakia?

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

Describe the adherence virulence factor of C. albicans.

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

Describe the host defences/damage.

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

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

disease process

Name 2 common anti fungal agents.

Polyenes - bind ergosterol in membrane | Azoles - interfere with ergosterol production

what anti fungal agent has anticandidal activity ?

Chlorohexidine

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

integration into cell membrane. | Example: Nystatin

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

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

Describe the action of Nystatin (polyenes).

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

what is miconazole an inhibitor of?

ergosterol formation

how is miconazole used systemically?

``` – Miconazoletaken absorbed by GI tract – Fluconazolesecretedin saliva – C.albicans – Candidaspeciesoften resistant ```

When are patients resistant to miconazole?

long term HIV therapy

what anti fungal resistance is most common?

azoles

Give example of azole resistance.

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

M20- Fungi- candida Flashcards

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