Acinomyces & Candida Flashcards
(13 cards)
21 species of Actinomyces: Which 5 cause the majority of disease
• A.israelii
Most frequent in actinomycosis
• A.oris
2nd most frequent
• A.odontolyticus
important in caries
• A.gerencseriae
important in caries
•A.meyeri
brain abscess
Actinomycosis (infectious disease caused by Actinomyces)
• Cervicofacial:
- acute painful
• Abdominopelvic:
ileocaecal
- Thoracic - farmer’s lung
- Cerebral - haematogenous spread
- Entry - mucosal break
- Histology - chronic inflammation, fibrosis
Pathogenic factors
- No toxins, no aggressive enzymes
- Virulence associated with:
- Induction of chronic inflammation
- Walling off from defences
- Slow growth as large aggregates in a matrix
Treatment
- Attempt at thorough surgical drainage
- Antibiotics 6-8 weeks:
- amoxicillin
- penicillin
- tetracycline
Candida
• Dimorphic fungus:
- blastospore (yeast)
- hyphae
- chlamydospores
Different candida species
- C.albicans
- C.tropicalis
- C.krusei
- C.glabrata
- C.dubliniensis
Habitat:
- Mouth, gut, vagina
Culture & Identification of Actinomyces
• Sabouraud’s dextrose medium:
- Creamy colonies
• C.albicans:
- germ-tube test - 3hr in serum 37 C
• Sugar utilisation tests:
- As sole source of carbon
Candidosis
• Predisposing factor
• Affects mucosa/skin
- systemic infection
- Oral
- Vulvo-vaginal
- Cutaneous; mucocutaneous
- Bronchopulmonary
- Systemic:
- endocarditis
- septicaemia
Oral Candidosis
- Acute pseudomembranous
- Chronic atrophic
- Chronic hyperplastic
- Acute atrophic
- HIV
- Angular cheilitis
Predisposing factors of Candidosis
• Prostheses - no exfoliation
• Low saliva - no flow, soluble defences
- low pH induced by high sugar diet
- Antibiotics - reduced bacterial competition
- Immuno-suppresison - no cellular defence - diabetes
Pathogenic factors
• Hypha - invasive structure:
- Blastospores - pro-inflammatory cytokines
- Hyphae - anti-inflammatory cytokines
- Proteases
- pH <6 favours blastospores
- pH >7 favours hyphae production
Other pathogenic factors
• C.albicans:
- IL-10 (immuno suppressive), slow TNFa production
• Phospholipases
• Adhesins:
- Ala3 and Ssa2 bind to E-cadherin
• Acid by-products of metabolism
- cause cell damage
Treatment
- Identify & remove predisposing factor
- Antifungal drugs:
POLYENES - bind to ergosterol, membrane leakage:
nystatin & amphotericin B
IMIDAZOLES - inhibit cytochrome P450 demethylase:
Miconazole & Fluconazole
Nystatin & Miconazole are topical. The other two are systemic
