Candida infections Flashcards
Where are the candida species found?
Common in the oral cavity, GIT and vagina as a commensal
Describe the shape of candida
Polymorphic fungus - it takes up many shapes
What is the importance of candida?
It is the most common fungal pathogen in humans, and the most medically important fungus
Describe the pathogenicity of candida
It is a harmless commensal and opportunistic mycoses, which develops mucosal infections in certain conditions e.g. immunocompromised
What species of candida is most important?
Candida albicans
What are the stages of candida albicans infections?
Colonisation Superficial infection Deep spread infection Disseminated infections (Host and fungal factors play a role in the development from superficial to deep seated infections)
List the predisposing factors for oral candidal infections
- Immunocompromised - diabetes, HIV/AIDs, cancer or chemo, organ transplants
- Drugs causing antimicrobial change to flora e.g. antibiotics
- Diet/nutrition - iron, folate or vit b12
- Mechanical and chemical - burns, wounds, smoking and dentures
- Xerostomia - medications, sjogrens
What cells are important for colonisation of candida?
Adhesion factors to anchor bacteria to epithelial walls
Enzymes to interact with cell membrane
Hyphae formation for adhesion
What are the adhesion factors in candida?
Agglutin like sequence 3
Hyphal wall protein 1
What type of bonding occurs between candida and epithelial walls
Covalent - therefore v strong
What enzymes are important in candida infections
SAPs - secreted aspartyl proteinases
Lipases
Phosphilipase Bs
How does superficial candida infection arise?
Penetration and anchoring of hyphae, causing degredation of epithelium via toxin production (candidalysin)
What is candidalysin?
Antimicrobial peptide (toxin) that integrates into the membrane and damages epithelial cells
Why is pain and itching associated with candida infections?
Due to toxin production
What occurs with disseminated candida infections?
Penetration through epi to major organs which can be fatal
How does the body attempt to clear candida infection?
Secretion of proinflammatory mediators to recruit neutrophils (direct killing) and dendritic cells (APC to th17 cells)
These secrete cytokines to kill fungi or repair epithelium
What cytokines are vital in candida infections?
TNFa
IL22 and IL17
What is the classification of oral candida infections
Acute - Pseudomembranous - Atrophic candidiasis Chronic - Hyperplastic - Atrophic Others - Erythematous - Angular chelitis
Describe the clinical features of: pseudomembranous candida
White patches which are easily removed on scraping
Associated with extremes of age
Describe the clinical features of: atrophic candidiasis
Depapillation of tongue - smooth and red
Associated with antibiotics
Describe the clinical features of: chronic hyperplastic candida
White or a mix of red and white patches
Looks like pseudomembranous but you cannot remove the plaque
Sites- BM adjacent to commissures
What is chronic hyperplastic candida associated with
Smoking
What is the important features of chronic hyperplastic candida
- Fungus is inside the epithelial cells
- Persistent lesions show epithelial dysplasia - considered OPML
Describe the clinical features of: chronic hyperplastic candida associated with median rhomboid glossitis
Back and middle of the tongue
Glossy appearance
Describe the clinical features of: Chronic atrophic candida (denture related stomatitis)
Erythema of mucosa associated with area covered by (upper) denture
Angular stomatitis is associated
Describe the clinical features of: erythematous candida
Erythema and smoothness of the middle of the dorsal tongue
Redness of palate corresponding to tongue
Longer lesion than MRG
What is chronic erythematous candida associated with
Denture wearing
Describe the clinical features of: angular cheilitis/stomatitis
Soreness, erythema and fissuring of the commissures (corners of the mouth)
What causes angular cheilitis
Leakage of candida infected saliva at the commissures
Risk factors for angular cheilitis
Deep folds due to age
Ill fitting dentures
Nutritional deficiencies
Describe the steps for the management of candida
- Establish diagnosis - clinical features and special tests
- Remove, reduce or manage risk factors
- Antifungal agents
What is CHROMagar
Special testing for candida to identify the strain (they appear as different colours)
What are the types of tests for candida?
Smear
Swab
Saliva
Biopsy
What mechanisms can antifungals affect
- Nucleic acid biosynthesis
- Ergosterol biosynthesis
- Membrane function
- Cell wall biosynthesis
How do Azoles work?
Prevent biosynthesis of ergosterol
How does Nystatin work?
Punch holes in the plasma membrane, resulting in lysis of the cell
What anti-fungals are involved in preventing cell wall biosynthesis
Echinocandins
Caspofungins
How do caspofungins work?
Prevent beta glucan synthesis which makes the cell walls - causes the candida to burst
What are the most commonly used antifungals in dentistry?
Nyastatin
Fluconazole
Miconazole
Intraconazole
What types of therapy is used for candida
Topical
Systemic
Describe topical antifungal therapy
Nyastatin in the form os lozenges and suspension
Miconazole gel for lips, tongue and denture fitting surfaces
How can dentures be treated if affected by candida
Placed overnight in:
Sodium hypochlorite
CHX
When are systemic antifungals considered
If local therapy doesn’t work
Or it is severe
Prophylaxis of candida
- CHX mouthwash daily if uncontrollable risk factors
- Rinsing mouth after using steroid inhalers
When should azoles be avoided
In pts taking NOACs/warfarin
Instead - nyastatin
