actinomyces and candida

Question 1

actinomyces properties and habitat

Answer 1

gram +
filamentous
uneven staining
sometimes shows branching
form colonies
facultatively anaerobic
habitat
commensal of mouth gut vagina

Question 2

diagnosis of actiomycosis

Answer 2

• microbiological culture
• immunoassay
• MRI

Question 3

what does actinomycosis affect and clinical presentation

Answer 3

• affected people often have just had dental treatment, poor OH, periodontal disease

Clinical presentation

• Large abscesses
• can penetrate bone and muscle to the skin
• can break open leaking pus

Question 4

histology of actinomycosis

Answer 4

chronic inflammation
fibrosis
eosinophilic terminal clubs
asteroid bodies (light blue area)
pus - often termed sulphur granules

Question 5

what are splendour-hoeppli reactions in histology

Answer 5

asteroid bodies
- between cationic proteans and lipids
involved in AgAb complexes tissue debris and fibrin

known as amorphous protein pS matrix

Question 6

what is the purpose of splendour-hoeppli reactions (asteroid bodies)

Answer 6

wall off infection rom the body
stops immune cells entering the area
- thought to be a localised immunological response to an AbAg precipitate related to fungi ect

Question 7

virulence of acitnomyces

Answer 7

• induction of chronic inflammation
• walling off from defences
• slow growth as large aggregates in matrix

no toxins or aggressive enzymes

Question 8

treatment of actinomyces

Answer 8

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

Question 9

what is candida and its types

Answer 9

Dimorphic fungus (Trimorphic) – a polymorphic organism

• blastopore (yeast)
• psudohyphae
• hyphae (chlamydospores)

Question 10

yeast

Answer 10

• smaller cells are daughter cells
• can have budding scars, thickening of the wall as the daughter cell buds off
• under certain environmental factors can form psudohypae

Question 11

psudohypae

Answer 11

• connected to mother via wall to wall interactions
• loosely connected but two separate organisms
• these can form hyphe

Question 12

hyphae

Answer 12

• still connected to mother cell
• no wall off
• thinner and longer than psudo
• all interconnected
• can bud (spores)

Question 13

habitat of candida Albans

Answer 13

• mouth
• gut
• vagina

Question 14

what can candida be cultured in and its appearance

• What tests can be used to test for candida albicans

Answer 14

Sabourauds dextrose medium

• white creamy colonies
• bread/beer smell (yeast)

1) germ tube test
Hypae start to form from the yeast form (3 hours in serum , 37 degrees or pH above 7)

2) Sugar utilisation tests
- as sole source of carbon
- grow on certain types of sugars

Question 15

what is chromatic agar

Answer 15

Incorporates two chromogens that indicate the presence of the target enzymes
- some candida species have enzymes and some don’t so will lead to different results

Question 16

what is X-NAG

Answer 16

detects activity of hexosaminidase

Question 17

what is BCIP

Answer 17

detect alkaline phosphatase activity

Question 18

how can candida develop

Answer 18

candida is a commensal
- individual has an underlying predisposing factor (e.g. immunosuppressed)
affects mucosa /skin
oral
vaginal

Question 19

candida infection systemically

Answer 19

endocariditis

septicaemia

Question 20

examples of candida infections in the mouth

Answer 20

acute psudomembranous (thrush)
chronic atrophic
chronic hyperplastic
acute atrophic
erythematous- HIV
angular cheilitis

Question 21

thrush/ acute psudomembranous

Answer 21

• candidia grows on the surface of oral mucosa
• tongue, back of throat
• white patches
• can scrape patches off and will show red patch underneath

Question 22

chronic atrophic candidacies (candidosis infeciton)

Answer 22

• candida under denture, between palate

- penetrate epithelium and damages

Question 23

chronic hyperplastic (candidosis infeciton)

Answer 23

• junction of lips
• predisposing factor smoking
• only form of candida which is associated with dysplasia and cancer progression

Question 24

acute atrophic

Answer 24

• red tongue

- associated with those on corticoid steroids (immunosuppressant) or on long term antibiotics

Question 25

erythematous

Answer 25

- red dots | - associated with those with HIV

Question 26

angular cheilitis

Answer 26

- cracked lip at junction | - predisposing factors diet and nutrition, HIV, immunosupressents

Question 27

predisposing factors to candida infection(exam)

Answer 27

- prostheses on top of epithelium, epithelium cannot shed off excess bacteria (no exfoliation) - low saliva (no flow, low soluble defences, candida can attach more firmly) - antibiotics (reduced bacterial competition) - immunosuppression (no T cell defence, diabetes, immunodeficiency)

Question 28

forms of candida and pathogenicity

Answer 28

1) yeast forms - commensal 2) hyphal forms - pathogenic

Question 29

factors which affect hypal transition

Answer 29

1) pH - less than 6 favours yeast, greater than 7 favours hyphae 2) nutrients - serum favours hyphae

Question 30

when are candida gees expressed pathogenic

Answer 30

when in hyphen form

Question 31

pathogenic/virulence factors of candida

Answer 31

agglutinin like sequence (only expressed by hyphae, important in adhesion to cells) hyphen wall protein (mediates adhesion to oral epithelial cells)

Question 32

adhesion and invasion to oral epithelium of candida

Answer 32

1) Yeast - genetically engineered candida that cannot form hyphae - sit on top of the wall 2) hyphal - mass penetration and destruction of the epithelium 3) Wild type - natural form, not GM - some yeast and some hyphal penetrating the epithelium

Question 33

how does candida invade tissues

Answer 33

Yeast to hyphal transition and growth is essential for virulence and pathogenesis Hyphae secrete Candidalysin - pore forming toxin that kills human cells and also initiates an immune response - secreted as monomers, come together to form a complex with pore in the middle - punches holes in epithelium

Question 34

apart from candida lysin what is also used to invade and move through epithelial cells

Answer 34

1) Sap 1-3 - needed for mucosal infection 2) Sap 1-3 - degrade complement 3) Sap 4-6 - contribute to systemic infection sap secreted at the tip of hyphae so the hyphae can progress Lipases/phospholipases - breakdown epithelial plasma membranes during hyphal penetration - initial access through the plasma membranes of the cell surfaces

Question 35

pathogenesis at mucosal surfaces of candida yeast spores

Answer 35

1) Yeast form attaches and starts to form hyphae (via a predisposing factor to for hyphae) - ALS5 and ALS1 protein on yeast cell surface which binds to the receptor on epithelial cell receptor - Beta glucan (sugar in the candida cell wall) binds to EphA2 on epithelial cells 2) epithelial invasion - Hyphae generated, B glucans still involved - ALS3 drives attachment (only expressed in hyphae not yeast) - HWP binds to epithelial cells as well - once hyphae bind, flicks down into cell and saps are generated, lipases secreted punching holes in epithelial cell membrane 3) growth - secretes candilysisin to punch holes in nearby cells 4) damage

Question 36

how can systemic pathogenesis occur

Answer 36

need a lesion to get access to blood stream

Question 37

how is candida treated

Answer 37

1) identify and remove pre disposing factor (eg low saliva, antibiotics) 2) Antifungal drugs - nystastin - micronazole Above are topical - fluconazole - amphotericin B (quite toxic) Above are systemic

Question 38

how do polyenes work

Answer 38

(Nystatin, AmphotericinB) - bind to ergosterol - causing membrane leakage of candida

Question 39

how do imidazole work

Answer 39

(micronazole, fluconazole) | - inhibit cytochrome P450 demethylase (converts lanosterol to ergosterol so affects membrane synthesis)