Actinomyces and Candida

Question 1

Actinomyces are

Answer 1

Gram-positive filaments, unevenly staining, sometimes showing branching

Question 2

Actinomyces species

Answer 2

21 species - 5 cause majority of disease in man

• A. israelii
• A. oris (naeslundii)
• A. odontolyticus
• A. gerencseriae
• A. meyeri

Question 3

A. israelii

Answer 3

Most frequent in actinomycosis

-sometimes with Ag. actinomycetemcomitans

Question 4

A. oris (naeslundii)

Answer 4

2nd most frequent

Question 5

A. odontolyticus

Answer 5

Important in caries

Question 6

A. gerencseriae

Answer 6

Important in caries

Question 7

A. meyeri

Answer 7

Brain abscess

Question 8

Actinomyces habitat

Answer 8

Mouth, gut, vagina

Question 9

Actinomyces culture

Answer 9

Fastidious - usuallu use brain-heart infusion
Microaerophilic/ facultatively anaerobic
Slow growing - 3-7 days, ‘molar tooth’ colonies

Question 10

Actinomycosis cervicofacial

Answer 10

55-65%
Acute painful
Chronic indolent with sinus
No lymphadenopathy

Question 11

Abdominopelvic actinomycosis

Answer 11

10-20% ileocaecal; IUDs

Question 12

Thoracic actinomycosis

Answer 12

Aspiration; farmer’s lung

Question 13

Cerebral Actinomycosis

Answer 13

Haematogenous spread

Question 14

Locations of actinomycosis

Answer 14

Cervicofacial
Abdominopelvic
Thoracic
Cerebral

Question 15

Actinomycosis entry

Answer 15

Mucosal break

Question 16

Actinomycosis histology

Answer 16

Chronic inflammation, fibrosis, eosinophilic terminal clubs

Question 17

Actinomycosis in pus

Answer 17

‘Sulphur granules’

Question 18

Actinomyces pathogenic factors

Answer 18

No toxins, no aggressive enzymes
Virulence associated with
-induction of chronic inflammation
-walling off from defences
-slow growth as large aggregates in a matrix

Question 19

Actinomyces treatment

Answer 19

Attempt at thorough surgical drainage
Antibiotics - 6-8 weeks
-amoxicillin
-penicillin
-tetracycline

Question 20

Candida

Answer 20

Dimorphic fungus (trimorphic)

• blastospore (yeast)
• hyphae
• chlamydospores

Question 21

Candida species

Answer 21

C. albicans (most frequent)
C. tropicalis
C. krusei
C. glabrata
C. dubliniensis

Question 22

Candida habitat

Answer 22

Mouth, gut, vagina

Question 23

Candida culture and identification

Answer 23

Sabouraud's dextrose medium - creamy colonies
C. albicans - germ-tube test
-3hr in serum, 37 degrees C
Sugar utilisation tests
-as sole source of carbon

Question 24

Candidosis

Answer 24

Predisposing factor
Affects mucosa and/ or skin
-systemic infection uncommon but serious
Oral
Vulvo-vaginal
Cutaneous; mucocutaneous
Bronchopulmonary
Systemic - endocarditis, speticaemia

Question 25

Oral candidosis types

Answer 25

``` Acute pseudomembranous Chronic atrophic Chronic hyperplastic Acute atrophic Erythematous - HIV Angular cheilitis ```

Question 26

Predisposing factors for oral candidosis: mainly

Answer 26

``` Prosthesis - no exfoliation Low saliva - no flow; soluble defences -low pH induced by high sugar diet Antibiotics - reduced bacterial competition Immuno-suppression - no cellular defence -diabetes ```

Question 27

Pathogenic factors oral candidosis

Answer 27

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 Phospholipases Adhesins -e.g. Ala3 and Ssa1 bind to E-cadherin Acid by-products of metabolism cause cell damage

Question 28

pH on pathogenic factors of oral candidosis

Answer 28

pH <6 favours blastospores | pH >7 favours hyphae production

Question 29

Other pathogenic factors C. albicans

Answer 29

IL-10 (immuno suppressive) Slow TNF alpha production no IL-12 or IFN gamma

Question 30

Treatment of oral candidosis

Answer 30

``` Identify and remove predisposing factors Antifungal drugs -nystatin -miconazole -fluconazole -amphotericin B ```

Question 31

Topical antifungal drugs

Answer 31

Nystatin | Miconazole

Question 32

Systemic antifungal drugs

Answer 32

Fluconazole | Amphotericin B

Question 33

Polyenes antifungal drugs

Answer 33

Nystatin and amphotericin B | Bind to ergosterol, membrane leakage

Question 34

Imidazoles antifungal drugs

Answer 34

Miconazole and fluconazole Inhibit cytochrome P450 demethylase -converts lanosterol to ergosterol, so affects membrane synthesis