Cutaneous and Subcu Mycoses - Stillwell Flashcards
1
Q
mycosis
A
fungal infection
2
Q
superficial mycoses
A
-fungal infection limited to outer layer (ex. tinea versicolor)
3
Q
dermatophyte infection
A
- fungal infection requiring keratin growth
- superficial infections on dead part of skin
- spread by direct contact and fomites
4
Q
subcu mycoses
A
- fungal infection of dermis, subcu, muscle or fascia
- deeper tissues
5
Q
systemic mycoses
A
- fungal infection that enters through respiratory or GI tract –> spread to other organs
- dimorphic, opportunistic
- affect immunocompromised
6
Q
dimorphic
A
- fungal infection in yeast and mold form
- mold at room temp, yeast at body temp**
- candida is exception**
7
Q
mold
A
- fungal infection containing branching hyphae**
- septated with pores –> cytoplasmic connections
- called mycelium
- fillamentous hyphae (ex. aspergillus, fusarium, rhizopus)
8
Q
yeast
A
- single celled and reproduce by budding
- contain pseudohyphae** (no cytoplasmic connections)
- elongate and stick together
- pseudohyphae –> think CANDIDA**
9
Q
tinea
A
-fungal infection of outer part of skin (ringworm, athlete foot, jock itch)
10
Q
mycetoma
A
- fungal and bacterial infection of subcu tissue
- enter through skin releasing “grains” of microorganisms**
11
Q
chromoblastomycosis
A
- chronic subcu fungal infection of TROPICAL climates**
- sclerotic (medlar) bodies**
12
Q
onychomycosis
A
-fungal infection of toenails/fingernails
13
Q
superficial mycoses - Tinea (pityriasis) versicolor
A
- cause: malassezia yeast**
- on skin as normal flora; trouble in warm/humid environment
- hyper/hypopigmented** lesions
- azeliac acid produces scaling circles**
- worry about sepsis in immunocompromised**
- spaghetti and meatballs on KOH stain**
- fluoresces on woods lamp**
- tends to relapse
14
Q
superficial mycoses - seborrheic dermatitis
A
- cause: malessezia?? –> produce azeliac acid which irritates skin**
- immunocompromised, Parkinson’s, Down syndrome
- worse in winter**
- dandruff on skinfolds, eyebrows, nose**
- treat: topical azoles (antifungals)
15
Q
superficial mycoses - cutaneous candida
A
- cause: Candida albicans
- infectious when it outgrows normal flora (ex. following antibiotic use)**
- satellite lesions around intertrigo**
- more reddish than erythrasma (corneybacterium minuttismus - more brownish, no satellite lesions, fluoresces under woods)**
- treat with topical anti fungal
- contain pseudohyphae on KOH stain**
16
Q
Cutaneous mycoses - dermatophytes
A
- deeper infections of skin, hair, nails –> itching, pruritus
- 3 different mycoses –> 1. microsporum, epidermophyton, trichophyton**
- trichophyton rubrum (main) and mentagrophytes most common**
- direct contact, viable up to 15 months
- path: secrete proteases, elastases, and keratinases for virulence factors**
- treat: cell mediated immunity (type 4 hypersensitivity); use topical or systemic antifungals if bad enough
- hyphae or arthrospores on KOH stain
17
Q
types of dermatophyte infections - tinea aka ringworms
A
- corporis - body
- cruris (jock itch) - inguinal, perianal, perineum
- pedis (athlete foot)
- manum - hands
- capitis - scalp; ectothrix (invade outside hair shaft, hair breaks above skin); endothrix (invade invade inside hair shaft, hair breaks at skin level –> black dot ringworm)
- unguium (onychomycosis) - nails
- faciei - face without hair
- barbae - face/neck with hair
- imbricata - tinea corporis in infants near tropics (waves of scales
- incognito - fungal growth with bacterial infection due to corticosteroids (bad)
18
Q
subcutaneous mycoses - cutaneous sporotrichosis (sporothrix/rose Gardners)
A
- cause: dimorphic fungi in soil, rosebushes, hay, wood –> farmer, Gardner, cats, veterinarian
- enter through abrasions or lungs –> sever in immunocompromised causing pneumonia
- nodule lesions tracking up lymphatic chain**
- silver stain –> cigar lesions**; grows on fungal culture
- can see granulomas, fibrosis, necrosis on histo
- treat: itraconazole usually; amphotericin in immunocompromised
19
Q
subcutaneous mycoses - mycetoma (Madura foot)
A
- chronic subcu fungal and bacterial infection
- mainly farmers –> inoculated through splinter/thorn
- 70% of time lesions seen on foot
- sinus tracts full of “grains” of microorganisms** –> form tumor or plaque
- treat: debridement or amputation
20
Q
subcutaneous mycoses - chromoblastomycosis
A
- traumatic inoculation of fungi –> granulomatous response
- usually lower extremities
- high rate of secondary bacterial infection
- sclerotic (medlar, copper penny) bodies on KOH stain**
- dark molds on fungal culture
- treat: surgical removal/amputation
21
Q
systemic mycoses - cryptococcosis (cryptococcus neoformans)
A
- encapsulated yeast that lives in soil or rotting wood
- enter through inhalation (respiratory problems)
- cause meningitis –> loves to travel to brain
- disseminated form causes skin lesions in immunocompromised (ex. HIV with low CD4)
- GMS (silver) and mucicarime stain –> narrow base budding**
- treat: amphotericin B
22
Q
systemic mycoses - histoplasmosis (H. capsulatum)
A
- get from inhalation of spores
- pulmonary infection
- secondary immune rxn with erythema nodosum
- immunocompromised –> skin and non healing oral lesions **
- granulomas and macrophages/monocytes engorged with yeasts** - parasites in Macs**
- common in AR
23
Q
systemic mycoses - blastomycosis (B. dermatitidis)
A
- enter through lungs (pneumonia)
- nodules in lungs and lymphadenopathy
- plaque like lesions
- broad/wide based budding on silver stain**
- commin in AR
24
Q
systemic mycoses - coccidioidomycosis (C. immitus)
A
- inhale spores –> pulmonary infections
- immunocompromised –> loves to travel to brain
- spherules enclosing multiple spores on stain**
25
Q
systemic mycoses - Paracoccidioidomycosis (P. brasiliensis)
A
- pulmonary symptoms
- mulberry like lesions on lips/face**
- silver stain showing multiple buds of single yeast**
- treat: azoles or amphotericin B
26
Q
zygomycetes (mucormycosis)
A
- caused by multiple types of fungi (very severe)
- in uncontrolled diabetic or immunocompromised**
- nonseptate hyphae that branch at 90 degrees**
- get through inhalation of spores and skin abrasions
- black necrotic plaques/eschars** –> invade tissue and blood vessels
- hard to treat, resistant to voriconazole**
27
Q
aspergillosis (Aspergillus)
A
- colonize bronchiole tubes in lungs –> affect COPD patients**
- disseminate in immunocompromised causing skin lesions
- septate hyphae branch at 45 degrees on silver stain**
- gang sign fungus**
- voriconazole drug of choice**
28
Q
parasite - pediculosis
A
- infestation of lice
- spread by direct/sexual contact and fomites (ex. helmets)
- vectors of louse-borne typhus, trench fever, relapsing fever**
- cannot burrow, look for nits
1. capitis - scalp region = head lice
2. corporis - body = Vagabond’s disease
3. pubis - pubic region = crabs
29
Q
parasite - scabies
A
- 7 year itch**
- due to burrowing mite (Sarcoptes scabiei) –> form tracts**
- allergic rxn to mites dying
- spread by direct/sexual contact or fomites
- b/w fingers, toes, hands, arms, waistline**
- symptoms/itch lasts for long time after treatment**
- treat: ivermectin
30
Q
parasite - chiggers (trombiculidae)
A
- small mites in forests or grasslands
- found on ankles and exposed areas**
- do not suck blood or burrow
- inject saliva/digestive enzymes that kill cells –> inflammatory response and itching**
- treatment: prevention, scratching makes it worse
31
Q
parasite - bedbugs (cimex)
A
- feed on human blood
- come out at night and bite**
- treat: hot steam cleaning
32
Q
parasite - myiasis (maggots/fly larvae)
A
- flies lay eggs on open wounds
- maggots/larvae usually only eat dead tissue (clean infection with sterile maggots)
- due to trauma or infected leg
- treat: lure with rotten meat
33
Q
parasite - cutaneous larva migrans** (Ancyclostoma braziliense)
A
- nematode larva of hookworms**
- found on beach in animal feces
- larvae burrow and crawl through human skin
- ground itch, creeping pruritic eruption**
- cannot live whole life in body or penetrate basement membrane (stay in epidermis)
34
Q
parasite - swimmers itch** - (cercarial dermatitis)
A
- schistosomes from infected birds or mammals that are released from snails in fresh/salt water**
- lesions after swimming (summer) –> allergic rxn to parasite
- cannot finish life cycle in humans and die
- treat: anti-itch and corticosteroids
35
Q
parasite - cutaneous leishmaniasis (oriental sore, delhi boil)
A
- transmitted by sandfly and is a zoonosis (animal–> human vector and vice versa)**
- in texas and middle east
- scar remains after healing
- soldier coming back from Iraq***
- amastigotes in monocytes with a nucleus and rod-shaped kinetoplasts**
- PCR also available
