Fungi L21 Flashcards
Transmission of Candida
Infection is endogenous, although cross infection can also occur (eg from Mother to child or amongst infant siblings)
Characteristics of Candida
Found as spherical or oval budding yeast
Single cells or blastospores
What are pseudo hyphae?
Elongated filamentous cells joined end to end
When can pseudo-hyphae be seen?
At lower incubation temperatures and on nutritionally poor media
What are true hyphae?
True hyphae are thread-like tubes that contain the fungal cytoplasm and its organelles.
What culture do C. Albicans grow on? How do they appear?
Grows on sabouraud agar, as creamy white colonies, flat or hemispherical in shape
Under which agar with what conditions does C. Albicans grow?
Sabouraud agar
High sugar, Low pH conditions
5 predisposing factors for growth of candida
- Chronic local irritants
- Ill-fitting appliances
- Dietary factors
- Immunological disorders
- Endocrinal disorders
What does superficial candidiasis affect?
Mainly the skin and epithelial surfaces
4 conditions caused by superficial candidiasis
- mucosal infection/thrush
- candida intertrigo
- nappy rash
- candida paronychia
What does mucocutaneous candidiasis affect?
Involves both the skin and the underlying mucosa
What deficiency is chronic mucocutaneous candidiasis associated with?
T cell deficiency
Treatment for chronic mucocutaneous candidiasis?
Systemic anti-fungal therapy
Where does systemic/deep candidiasis occur?
In most organs following candidaemia (candida in blood)
Who are at risk of systemic/deep candidiasis? (X3)
Seriously ill patients
Patients who had heart surgery/organ transplant
Patients who are on Long term immuno suppression drugs/drug therapy
4 forms in which oral candidosis could present in?
- Pseudo-membranous candidosis (PMC/thrush)
- Erythematous candidosis
- Angular cheilitis
- Chronic hyperplastic candidosis (candida leukoplakia)
Name four groups of people who are likely to get erythematous candidosis
- Denture wearers
- Prolonged drug therapy - antibiotics / topical steroids
- Persistent PMC
- AIDS patients
Treatment for patients with erythematous candidosis caused by denture-wearing (x3)
- Topical antifungal agents - chlorhexidine
- Clean Dentures
- removal of dentures at night
Treatment for patients with erythematous candidosis caused by prolonged drug therapy
Topical antifungal agents
Stop administration of antibiotics
What is angular cheilitis caused by?
Overgrowth of C. Albicans at the angle of the mouth
Groups of people prone to angular cheilitis? (X2)
- Denture wearers
2. People with vitamin deficiencies (iron and vit b12)
Treatment of angular cheilitis (x2)
- Resolve underlying problem
2. Antifungal agents
If a patient presents with individual lesions of red/white speckled patches, with the surface being parakeratinised and hyperplastic, what disease could it be?
Chronic hyperplastic candidosis (candida leukoplakia)
Symptoms of chronic leukoplakia
- individual lesions
- red/white speckles
- parakeratinised and hyperplastic surface
Virulence factors contributing to the adherence of C. Albicans (x4)
- hyphal form
- hydrophobic surface contains non-specific adherence process
- expansion of cell surface specific adhesion molecules
- fibrillary mannoprotein
Virulence factors of C. Albicans promoting host defences/damage
Secreted aspartyl proteinases (SAPs)
Phospholipase
Concentrated at hyphal tip
Name 3 main groups of antifungal agents
- Polyenes
- Azoles
- Antimetabolite - 5-fluorocytosine
Give 2 examples of Polyenes
- Amphotericin B
2. Nystatin
Mode of action of Polyenes
Binds to ergosterol in fungal lipid membrane - makes the membrane leaky
Name a fungicidal agent and a fungistatic agent
Fungicidal: Polyenes
Fungistatic: Azoles
Name the Azoles (x5)
Imidazoles - miconazole and ketoconazole
Triazoles - itraconazole, fluconazole, triazole
Name an example of an anti metabolite
5-fluorocytosine
Habitat of Candida
Indigenous to the oral cavity, GI tract, female genital tract and sometimes the skin
