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56 Cards in this Set

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What are the three types of fungal infection?

1. Superficial


2. cutaneous


3. systemic/deep

Describe protection from skin.

1. physical barrier against fungal infections


2. protect underlying tissues

Why more bacteria growth found on wet skin than dry skin?

bacteria need water for growth so prefer wet/moist areas

Where does superficial mycoses occur?

stratum corneum of epidermis and hair shafts



give one example of superficial mycoses and the fungi responsible. and what are the symptoms?

Pityriases versicolour


by malasseia furfur


symptoms :


- flaky skin


- loss of pigmentation


- hyperpigmentation

What does malasseia furfur look like under microscope?

spaghetti and meatballs

Where does pityriases versicolour affect on the body

mainly trunk and proximal part of limbs

What causes malasseia furfur to turn off commensalism to pathogenic?

unknown stimuli

What does cutaneus mycoses affect?

keratinized layers of skin, nails and hair

what is the abundance of keratinocytes in skin?

90%

What species of fungi are usually responsible for cutaneous mycoses?

dermatophya

what is the source of infection of cutaneous mycoses?

infected animals, soil, humans

hoe does one get infected with cutaneous mycoses?

come in contact with arthrospores

What are the common disease regarding cutaneous mycoses?

Tinea/Ringworm

How does arthrospores infect the body?

Arthrospoers attach and invade and colonize the keratinized layer of skin, nail and hair. Does not invade living tissues.

How does dermatophytes obtain nutrients?

dermatophytes have keratinase enzyme that can use keratinocytes as nutrition source

what are the symptoms to dermatophytosis? and what causes these symptoms

allergic and inflammatory (non contagious) response of skin due to production of metabolic end products

What does the inflammatory response look like?

red raised circular lesions


flaky, itchy

What is the most common type of tinea?

tinea corporis

What does tinea pedis effect are wcutaneous mycoses and what are the symptoms of tinea pedis?

tinea pedis affect the food


itching


toe web maceration of skin


redness of 1st and 2nd toes


minima inflammation

how is tinea pedis spread?

coming in contact with desquamated skin cells in carpets/shoes

What is the diagnosis of dermatophytosis?

1. clinical assessment


2. collect skin swab (from ring where viable and growing cells are)


3. culture on sabourands agar (SAB)


4. using wood's light

What is SAB and what are its characteristics?

SAB = sabourands agar


- low pH


- high sugar content

what are the uses of SAB?

1. growth of fungi indicated by pigmentation


2. see formation of mycellium on plate

What is wood's light? How does it work?

form of diagnosis for fungal infections e.g. dermatophytosis


work by shining UV light causing fluorescence of infected area (scalp/skin)

where does microsporum canis effect on the body?

mainly scalp, and glabrous skin

what is the source of infection of microsporum canis?

infected cats and dogs



What is the fungi that causes vaginal thrush and balantis?

candida albicans (yeast)





what are the symptoms of vaginal thrush?

thick milky curd-like discharge

what are the symptoms of balantis?

inflammation of foreskin/head of penis


red lesions

What are the causes of vaginal thrush?

1. use of broad spectrum antibiotics


- kill normal vaginal flora


e.g. decrease in lactobacillus, increase in pH overgrowth of candida albicans.




2. oral contraceptives/pregnancy


- increase in glycogen content in blood



what is the normal pH of the vagina?

3.5 - 4.5

What is the diagnosis of vaginal thrush?

lower vagina swab


examine on SAB

What are the treatments for candida albicans for male and female?

male - treatment only if symptomatic (balanitis)


female - antifungal topicals

Why does males need to test for diabetes if they have balanitis?

diabetes = increase blood sugar content


favourable towards growth of candida albicans



How does a baby contract oral-candidasis?

1. natural birth, contracted via birth canal


2. breastfeeding


3. use of broad spectrum antibiotics



How does an adult contract oral-candidasis?

with immuno-suppressed systems


e.g. HIV/AIDS, transplant, diabetes

What is the symptom of baby oral-candidasis?

white creamy-looking pseudomembrane in inner mouth

what fungi causes most systematic fungal infections?

cryptococcos neoformans

What do cryptococcus neofoman look like?

encapsulated yeast

what is the function of the capsule on cryptococcus neoformans?

prevent attack of immune system getting to cell

What is cryptococcus neoformans transmitted?

by inhalation of airborne cells e.g. bird faeces

what happens when an immunosuppressed person contracts cryptococcus neoformans?

more likely to have fungal meningitis

What are the immediate and late stage symptoms of fungal meningitis?

early - headache, nausea


late - coma, loss of vision

What is the diagnosis for cryptococcus neoformans?

1. India Ink Stain


2. fluorescent stain


3. antibody-antigen latex agglutination test

How does the antigen-antibody latex agglutination test work?

blood from patient contains antigen of cryptococcus neoformans.


mix blood with antibodies to allow agglutination


latex allow the visualization of agglutination

What is the advantage of the antigen-antibody agglutination test?

can test for cryptococcus neoformans 22 days before onset of symptoms.

What are the 3 types of antifungal agents used to treat cryptococcus neoformans? give drug example of each class

1. polyenes


- amphotericin B


2. azoles


3. flucytosine

what is the mechanism of polyenes?

1. polyenes bind to ergosterol in the cell membane


2. insert itself into the membrane


3. cause leakage of cations

What are the side effects of polyenes?

renal toxicity


if polyene bid to host cholesterol --> TOXIC

What fungal infection is polyene used to treat?

systematic infections

what is the mechanism of azoles?

1. block synthesis of ergosterols


2. accumulate toxic intermeiates within cell


3. cause cell stress

What fungal infection does azole treat?

superficial and cutaneous

what is the mechanism of flucytosine?

inhibit DNA and RNA synthesis

What fungal species does flucystine act upon?

candida albicans


cryptococcus neoformans

What is done to oversome flucysteine resistance?

use flucytosine in combination with amphotericin B (polyenes)