Actinomyces and Candida Flashcards

Morphology and pathogenic features of Actinomyces and Candida species Main pathological conditions caused by these organisms Aspects of treatment

1
Q

Actinomyces

Most frequent and often found with

Habitat

A

Gram +ve
Sometimes branch
Uneven staining
21 species

A. israelii - aggregatibacter actinomycetemcomitans

A. oris, odontlyticus and gerencaeseriae –> caries

Mouth, gut, vagina

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2
Q

Culture

A

Fastidious
FACULTATIVE anaerobe
3-7 days to grow

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3
Q

Clinical presentation of actinomycosis

Aetiology

large abscesses can

A

Rare infection
Painful slow growing abscesses –> chronic infection

Recent tx, poor OH or periodontal disease

penetrate bone and muscle through to skin –> leak pus

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4
Q

Types of actinomycosis and examples

Histology

Mechanism

A
Cervicofacial - acute painful 55-65% 
Abdominopelvic - 10-20% - ileocaecal 
Thoracic - farmer's lung
Cerebral - haematogenous spread 
Entry - mucosal break 

Chronic inflammation, fibrosis and eosinophilic terminal clubs

Eosinophils try to destroy pathogen –> degranulation

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5
Q

Histology of actinomyces related disease

A

Club shaped lipid complexes around amorphous protein polysaccharide
Locules of pus surrounded by fibrous septa

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6
Q

Pathogenic factors

Virulence mechanisms

A

No toxins or enzymes

  1. induction of chronic inflammation
  2. walling off from defences
  3. slow growth due to large aggregates in a matrix
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7
Q

Treatment

A
Surgical drainage 
6-8 weeks antibiotic course 
- amoxicillin 
- tetracycline 
- penicillin
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8
Q

Candida

A
Features of organism 
opportunistic dimorphic fungus
- blastospore - yeast 
- pseudohyphae 
- hyphae
- chlamydospores
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9
Q

Candida species

Most frequent

A

C. albicans

Mouth, gut, vagina

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10
Q

Culture and ID of candida

3 methods

A
  1. Dextrose medium - +ve creamy colonies
  2. germ-tube test (for albicans)
  3. sugar utilisation tests
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11
Q

Candidosis/candidiasis

Pre-Deposing factor

Affects

presentations?

systemic effects?

A

Immunodeficiency

Mucosa and/or skin - red lesions caused by hyphae breaking open cells and disrupting epithelium

  • vulvo-vaginal
  • oral
  • cutaneous and mucocutaenous
  • bronchopulmonary

Endocarditis and septicaemia

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12
Q

Oral candidosis
Different types, what does it effect

Hyphae often live

A
  1. Acute pseudomembranous candidosis - thrush - immunodeficiency - redness below white lesion
    Hyphae difficult to phagocytose and live within macrophages
  2. Chronic atrophic
    - associated with denture wear on hard palate and upper jaw
  3. Chronic hyperplastic - buccal mucosa or tongue border - carcinogenesis and pre malignant lesions - colonise dysplastic lesions t accelerate malignancy
  4. Acute atrophic
  5. Angular cheilitis - occurs at corners of mouth
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13
Q

Predisposing factors of candidosis

A

Prostheses - lack of exfoliation –> XS build up of candida

Low saliva - no flow –> soluble defences and candida build up / low pH due to diet

Antibiotics - reduced competition

Immunosuppression - no cellular defence e.g in diabetes

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14
Q

Pathogenic features

  1. hyphae
  2. proteases

Which pH for which

A
  1. invasive i.e blastospores and hyphae (inflammatory and anti-inflammatory cytokines)
  2. secreted aspartyl proteases against proteins
    - destroy tissues and secreted from front of hyphae
    - mucosal infection
    - degradation of complement
    - systemic infection
    - make space for movement
  3. pH <6
  4. pH >7 forms anchor points to blast cells open
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15
Q

Other pathogenic factors

  1. C. albicans hyphae
  2. phospholipase
  3. Adhesins
  4. acid by products of metabolism
A
  1. IL-10 - immunosuppressant, candidalysin, blastospores have slow TNF-α production
  2. breakdown of phospholipid layers
  3. bind to proteins within cell
  4. cause cell damage
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16
Q

Treatment of Candidiasis

Examples

A

Identify and remove predisposing factor
anti fungal drugs

Polyenes and imidazoles

Nystatin and amphotericin B
- initiate membrane leakage

Micnazole, fluconazole
- inhibit cytochrome p450 demethylase - affects membrane synthesis