Actinomyces and Candida Flashcards
What are actinomyces?
Gram pos filamentous bac, uneven staining, sometimes show branching
How many actinomyces species exist?
21 species - 5 cause majority of disease in man
List the main actinomyces that cause disease
A.isreelii - most frequent in actinomycosis, sometimes with AA A.oris - 2nd most freq A.odontolyticus - important in caries A.gerencseriae - caries A.meyeri - brain abscess
What is the habitat of actinomyces species?
Mouth, gut, vagina
How is actinomyces cultured in the lab?
Fastidious - usually use brain-heart infusion
Microaerophilic/facultatively anaerobic
Slow growing - 3-7 days - colonies look like molar teeth
What is Actinomycosis?
How to diagnose it?
Rare infec disease
Painful slow growing abscess - months
Affected people often just had dental treatment, poor oh, PD
Diagnosis - microbiological culture, immunoassay, MRI
Where is actinomycosis located?
- Cervicofacial - 55-65% = acute, painful or chronic indolent (little pain) with sinus - no lymphadenopathy
- Abdominopelvic - 10-20% IUDs
- Thoracic - aspiration
- Cerebral - mucosal break
Entry of actinomycosis?
Mucosal break
Histological presentation of actinomycosis?
Chronic inflam, fibrosis, eosinophilic terminal clubs
In pus - sulphur granules
Pathogenic factors of actinomyces?
No toxins or aggressive enzymes Virulence associated with; - Induction of chronic inflam - Walling off from defences - Slow growth as large aggregates in a matrix
Treatment of actinomycosis?
Surgical drainage Antibiotics - 6-8 weeks: - Amoxicillin - Penicillin - Tetracycline
What is candida?
Dimorphic fungus; can exist as a: - Blastospore (round) - Hyphae - Chlamydospores (oval) Cause opportunistic infecs
List candida species
C.albicans - most frequent C.tropicalis C.krusei C.glabrata C.dubliniensis C.auris - 2009 increasing systemic infection
Candida species habitat?
Mouth, gut, vagina
How to culture and identify candida? (how to grow it)
- 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 features?
Predisposing factor Affects mucosa and/or skin - systemic infec uncommon but serious Red lesions - epi disrupted Oral Vulvo-vaginal Cutaneous; mucocutaneous Bronchopulmonary Systemic - endocarditis, septicaemia
Name the types of oral candidosis and their features
Acute pseudomembranous (thrush) (when white layer removed = red underneath)
Chronic atrophic = associated with dentures, not very painful just irritating - difficult to eat
Chronic hyperplastic = forms in gap in tissues, more difficult to rub off, associated with premalignant lesions, speckled white lesions
Acute atrophic = tongue is cracked and split, usually on dorsum of tongue
Erythematous-HIV = red lesions
Angular chelitis = at corners of mouth, cracking of mucosa
Predisposing factors of candidosis?
Prostheses - no exfoliation
Low saliva - no flow; soluble defences
- Low pH indued by high sugar diet
Antibiotics - reduced bacterial competition
Immuno-suppression - no cellular defence - diabetes
Pathogenic factors of candida?
Hypha - invasive structure
- Blastospores - pro-inflammatory cytokines
- Hyphae - anti-inflammatory cytokines
Proteases - secreted aspartyl proteases
- Sap 1-3 = needed for mucosal infection
- Sap 1-3 = degrade complement
- Sap 4-6 = Contribute to systemic infection
Ph<6 favours blastospores
Ph>7 favours hyphae production
C.albicans - IL-10 (immunosuppressive) slow TNFα production, no IL-12 or IFNγ, C. albicans avoid host defence
Phospholipids
Adhesins - Ala3 or Ssa1 bind to E-cadherin
Acid by-products of metabolism - cause cell damage
Treatment of candida?
Identify and remove predisposing factor Antifungal drugs; - Nystatin = topical, polyenes - Miconazole = topical, imidazoles - Fluconazole = systemic, imidzoles - Amphotericin B = systemic, polyenes
Polyenes - bind to ergosterol, membrane leakage
Imidazoles - inhibit cytochrome P450 demethylase = affects membrane synthesis
