Fungi and infestations Flashcards
dermatophyte - tinea/ringworm common
-there are three types of the dermatophyte genera that cause tinea/ringworm
>trichophyton. affects where (3)
>microsporum. affects where (2)
>epidermophyton. affects where (2)
>trichophyton. affects skin, hair, nails
>microsporum. affects skin, nails
>epidermophyton. affects skin, hair
dermatophyte - tinea/ringworm
- invades what layer of the epidermis. inflammation is caused by (2)
- risk factors (3)
- invades stratum corneum. inflammation a result of fungal metabolic products or delayed hypersensitivity.
- sharing of washing facilities, frequent use of swimming pools, occlusive footware spores can reside which encourages relapse.
dermatophyte - tinea/ringworm
-presentation depends on site and strain. dermatophyte spread from animals to humans is more severe than human to human.
different patterns (6)
- tinea pedis/atheletes foot
- tinea of nails
- tinea of hands
- tinea of groin
- tinea of trunk and limbs
- tinea of scalp
tinea pedis
-dmc. morphology of interdigial spaces (1). of soles (1) what lesions (1)
tinea of the nails often associated with tinea pedis.
-dmc. free edge of nail becomes (2). nail signs (2)
- soggy scaling of interdigital spaces. dry scaling of soles. also vesicles.
- free edge of nail becomes yellow and crumbly. also subungal hyperkeratosis and thickening.
tinea hands - usually associated with tinea pedis and tinea nails
-dmc - symmetrical?(1) characteristic surface (1) colour (1)
tinea groin
-affects men or women more(1). dmc - lesion (1) borders (1) course (1). distribution in contrast to candiadis what is usually spared. (2) surface (1) what lesions may be within main lesion (2).
tinea hands
-usually asymmetrical. characteristic powdery scale of creases of palm. mild erythema.
tinea groin
-affects men more(1). dmc - plaque. well demarkated border. lesion slowly expands. involes groin area, upper inner thigh, scrotum usually spared. scaly surface. vesicle and pustile may occur within plaque lesion
tinea corporis - tinea of trunk and limbs
-dmc - lesion (1) surface characteristics (2) colour (1) course (1)
tinea scalp
-usually affects who (1)
- fungi from humans. surface characteristics (2). inflammation?(1)
- fungi from animals. inflammation?(1) surface characteristics (3) Sx(1) complication (1).
-tinea corporis
>plaque. scaling, healing within middle leaves typical ring like pattern.. erythematous. slowly expands.
tinea scalp
-usually affects children
- fungi from humans. scaling, balding. inflammation minimal
- fungi from animals. inflammation more intense. pustulation, crusting, balding this presentation aka kerion, often mistaked for bacterial infection. lymphadenopathy. complication is scarring alopecia balding may be permenant.
dermatophyte - tinea/ringworm
-investigations (2)
-microscopic examination of scraping, culture
-dermatophyte - tinea/ringworm
-Mx
- topical. applied how often(1). imidazole preperation eg (2). allylamine preperations eg (1). if topical nail preperations used over sysemtic treatment it is applied how often for how long (2)
- systemic. needed for which kind of infections (2). medications used (3)
-topical
> applied twice daily. imidazole preperations - clotrimazole, miconazole. allylamine preperations - terbinafine. topical nail preperations applied twice a week for 6 months.
-systemic
>needed for nails, scalp or chronic infections of skin that have not responded to topical.
>itraconazole , terbanafine, griseofulvin
- some antifungals that can be use systemically
- terbinafine.moa. course for scalp (1) for finer nails (1) for toe nails(1). pro (1).
-itraconazole. moa. con (1). wide spectrum therefore also used for (2)
-griseofulvin. used for (1) cons (2). contraindicated in who (3)
-terbinafine
>fungicidal. 4 wks for scalp. 6 weeks for fingernail. 3 months for toe nail. pro is it is very effective and rapid acting relative to other antifungals.
-itraconazole
>fungistatic. con is interferes with c-p450 therefore pt requires medication review. wide spectrum therefore also used for candida infection and malassezia furfur
-griseofulvin
> used for scalp.cons are side effects (may cause headaches, nausea, vomiting, skin reaction) and interactions with some anticoagulants. contraindicated in pregnancy, liver failure, prophyria.
malassezia furfur - a form of yeast. formerly known as pityrosporum
-what are two common conditions attributied to this yeast (2)
- seborrhoeic eczema
- pityriasis versicolour
malassezia furfur - pityriasis versicolour
- caused by overgrowth of the commensal yeast malassezia furfur. particularly in what condition(1)
- dmc - colour (1) surface characteristics (1) usual distribution (1). course (3)
-Mx
>topical application of imidazole antifungals. eg (2) applied for how long (1)
>alertnative
- humid conditiosn
- dmc - lesions are depigmented in colour. slighly scaly. usually upper trunk. persist if untreated, depigmentation may remain after treatment, recurrance common.
- Mx
>clotrimazole, miconazole. every night for 2-4 weeks.
>OR equally effective, more irritant can use selenium sulphide mixture. messy applied to patches before bed washed off next morning. applied 3 times at weekly intervals.
malassezia furfur - sebborhoeic eczema
-dmc covered in eczema deck
-Mx - treatment is supressive rather than curative
>topical imidazoles eg(2) usually first line. for severe may use systemically.
>other options (4)
- clotrimazole, miconazole
- other options are topical sulphur, salicyclic acid, selenium sulphide preparations. also weak steroids.
scabies. caused by mite. bites are 0.3mm so hard so see unless with lens. transfered only via direct skin-skin contact.
- course. in a first attack after 4-6 wks what symptom starts(1) particularly bad when(1). how does this differ in a second attack(1). persists if untreated. recurrance common. most common in what seasons (2)
- distribution - rash is worst where (1). where is this usually on the body. where to look for borrows (6)
- morphology. type of lesion (1) surface features (3) another sign to look for (1)
- in first attack itching starts after 4-6 wks. in second attack starts after 1-2 days. itching particuarly bad at night. most common in autumn and winter.
- distribution - rash is worst where mites were feeding a 1-2 days previously. rash usually worst on trunk. look for borrows where mites lay eggs. borrows usually found fingers, sides hands, feet. flexures of wrists, elbows, ankles.
- papules. may be scaly, excoriated, urticarial. look for borrows
-investigations (2)
-investigations
>microscopy - with practice can pick a mite from edge of burrow. if not scraping from burrows can show mites and eggs
>dermatoscopy to see mite
- Mx can be started on clinical grounds even if mite cannot be found
- >*treat who (1)
>treat with what (1) eg(2) apply how (1)
- Mx
- >*treat whole family
>treat with a scabicide. eg - permethrin, malathion. can apply with a paintbrush. number of applications required varies between dermatologists. eg twice one week apart, leave on for 12 hrs
