4 - Biofilm 3: Candida Flashcards
How does size impact candidal infections?
- yeast cells approx 25-50x bio volume of bacteria
- less cells occupy more space in infection
- provide scaffold for bacteria and create protective environment
Define a mycofilm.
Fungi and bacteria incorporate in a symbiotic relationship where fungi provide attachment and protection of the bacteria
What are risk factors for developing candidiasis? (11)
- immuno-compromised or suppressed patients
- HIV
- intra-abdominal surgery
- central venous catheter
- parenteral nutrition
- broad-sprectrum antibiotics
- dialysis
- diabetes
- burn patient
- trauma patient
- long term steroid use
What are the classifications of oral candidiasis?
- pseudomembranous
- erythematous
- hyperplastic
- angular cheilitis
- chronic mucocutaneous (systemic infection with oral manifestations)
Give an example of pseudomembranous oral candidiasis.
Thrush
Give an example of erythematous oral candidiasis.
- atrophic (HIV related)
- denture related
Give an example of hyperplastic oral candidiasis.
Candidal leukoplakia (possible pre-malignant)
Describe a pseudomembranous candidal infection.
- commonly known as thrush
- easily wiped off mucosa
- is common in HIV patients or those who use systemic antibiotics
Describe a chronic hyperplastic candidal infection.
- is within tissue
- cannot be wiped off
- requires a biopsy to test for pre-malignancy
- requires systemic anti-fungal to treat
Describe angular cheilitis.
- Candida interacts with gram positive staph bacteria
- requires myconazole to treat
What is Newton’s type 1 stomatitis?
Localised inflammation
What is Newton’s type 2 stomatitis?
Diffuse inflammation
What is Newton’s type 3 stomatitis?
Granular inflammation
Describe denture induced stomatitis.
Candida adhere and colonise acrylic surfaces by co-aggregation and biofilm formation
What are signs and symptoms of denture induced stomatitis?
- inflamed mucosa
- burning sensation
- discomfort
- bad taste
What are the common oral pathogenic yeasts?
- Candida albicans
- candida glabrata
What anti fungal is Candida albicans sensitive to?
- fluconazole
- metroconazole
What anti fungal is Candida glabrata sensitive to?
Nystatin
Describe the morphogenesis of Candida albicans.
- innocuous form when at rest (round)
- stressed form develops a hyphae which can invade tissue and access the blood stream
- adhesion -> hyphal penetration -> vascular dissemination -> endothelial colonisation
What are hydrolytic enzymes?
Enzyme that catalyses the hydrolysis (breakdown) of a substrate through the addition of water
Give examples of hydrolytic enzymes.
- phospholipase
- haemolysin
- proteinase
Describe phospholipase.
- hydrolytic enzyme
- lipid is substrate
- contributes to infection by host cell penetration
Describe haemolysin.
- hydrolytic enzyme
- RBC are substrate
- contributes to infection by facilitating hyphal invasion
Describe proteinase.
- hydrolytic enzyme
- protein is substrate
- contributes to infection by adhesion to epithelial cells
How does Candida contribute to oral cancer?
- yeast products can produce alcohol
- alcohol is not carcinogenic, but the breakdown products are
- acetaldehyde is a carcinogen which causes damage to DNA
- therefore, alcohol dehydrogenase drives biofilm formation and possibly malignancy
What are the different laboratory techniques for diagnosing candidal infections?
- microscopy (smear)
- culture (oral rinse, swab, foam pad)
- histology (biopsy)
Why is it important to diagnose the species of candida?
Different candida are sensitive to different antifungals, and the incorrect treatment can cause overgrowth of the fungi and can be dangerous
What do azoles treat?
- work indirectly on the synthesis pathway of ergosterol
- fungistatic
- treat Candida albicans
What do polyenes treat?
- act directly on ergosterol by binding to it, and forming pores to leak cytoplasm
- fungicidal
- treat candida glabrata
Give examples of azoles.
- fluconazole
- metroconazole
Give examples of polyenes.
- nystatin
- amphotericin B
What is the dual-resistance mechanism?
Staph bacteria coat themselves in candida and becomes resistant to vancomycin
