Common Fungal & Parasitic Skin Pathogens Ehi Ediale

Microbe BG Infection Diagnosis Rx

- Dimorphic: forms Classic cutaneous candidiasis: Wet mounts of tissue samples in Topical azoles,
pseudohyphae and budding - Beefy-red patches and plaques with satellite papules and KOH show budding yeast, and nystatin
yeasts at 20°C, germ tubes at pustules at the periphery pseudohyphae.
37°C - Typically affects intertriginous areas (axillae, groin folds, etc) Oral anti-fungals in
- Babies: diaper rash severe cases:
fluconazole

Candida albicans
Fungal

- Branching septate hyphae Tinea capitis - Collect sample from active Topical antifungals:
- Occurs on head, scalp. border of a plaque. Visualize - Azoles
- Typically cause superficial - Transmission: direct contact with an branching septate hyphae on - Butenafine
infections—only involving infected individual or animal or from KOH with blue fungal stain - Ciclopriox
epidermis contact with a contaminated object
(eg, comb, brush, or hat)
- “Virulence factors”: - Multiple scaly patches with alopecia If refractory or
o Adhesin: adhere to keratin Tinea corporis extensive
(Dermatophytes)
o Proteolytic enzymes - Occurs on torso. involvement:
Microsporum,
(proteases, lipases, etc): - Erythematous scaling rings - Oral griseofulvin,
Trichophyton,
invasion (“ringworm”) and central fluconazole, etc
Epidermophyton
clearing
- Spread centrifugally
- Can be acquired from
infected cat or dog.
Tinea cruris
- Occurs in inguinal area
- “Jock itch”
- M>F
 - RFs: sweating, obesity, DM, etc - To determine exact causative
dermatophyte, culture on
Sabouraud’s agar
o Morphology used to
differentiate between
them

Tinea pedis
- Occurs on feet
- Transmission: direct contact with
the causative organism, as may
occur by walking barefoot in locker
rooms or swimming pool facilities.

3 Types:
- Interdigital (most common)
- Moccasin distribution
- Vesicular type

Tinea unguium
- “Onychomycosis”
- Occurs on nails.

- Yeast-like fungus Tinea (pityriasis) versicolor “Spaghetti and meatballs” Treatment:

- Normal inhabitant of the skin - Oval scaly macules, papules, and patches typically appearance on microscopy Selenium sulfide,
o Infection promoted by concentrated on the chest, shoulders, and back - Clusters of budding yeast cells topical and/or oral
heat and humidity - On dark skin the lesions often appear as hypopigmented mixed with hyphae antifungal
- Not a dermatophyte!! areas, whereas on light skin they are slightly erythematous medications.
- Less pruritic than or hyperpigmented
dermatophytes - Can occur any time of year, but more common in summer
Malassezia furfur - Produces lipolytic enzymes (hot, humid weather).
that degrade lipids à
production of acids that
damage melanocytes and
cause hypopigmented,
hyperpigmented, and/or pink
patches.
 - Mite with round body and Scabies - Identify mites or eggs in - Permethrin
eight short legs. - Mite burrows into stratum corneum à scabies superficial skin samples (via cream
- Too small to be seen with - Pruritus (worse at night) scraping) taken from skin - Washing/drying
naked eye. o Caused by a hypersensitivity response to feces of the lesions all
mite clothing/bedding
- Burrows (lines) in webspace of hands and feet, flexor - Treat close
Sarcoptes scabiei surfaces of wrists, elbows, axillae, buttocks, genitalia contacts
(Scabies) - RFs: children, crowded
populations (jails, nur sing
homes)
- Transmission: skin-to-skin
contact (most common) or
via fomites.

Cutaneous leishmaniasis - Skin biopsy: amastigotes in Treatment

- Obligate intracellular - Chronic, painless skin ulcers macrophages depends on
flagellated protozoans o Bite à papule à ulceration severity
Parasitic

- Vector: Sandfly Mild: resolve

o Sandfly carries the without treatment
promastigote form and (2-15 months)
injects into humans
- Endemic areas: Saudi Arabia, Severe: oral
Leishmaniasis Iran, Afghanistan, Brazil and miltefosine
Peru
1. Craddock, Lauren N., and Stefan M. Schieke.. "Superficial Fungal Infection." Fitzpatrick's Dermatology, 9e Eds. Sewon Kang, et al. New York, NY:
McGraw-Hill, , http://accessmedicine.mhmedical.com/content.aspx?bookid=2570&sectionid=210432218.
2. . "Brief Summaries of Medically Important Organisms: Introduction." Review of Medical Microbiology & Immunology: A Guide to Clinical Infectious
Diseases, 15eEds. Warren Levinson, et al. New York, NY: McGraw-Hill,
, http://accessmedicine.mhmedical.com/content.aspx?bookid=2381&sectionid=187698504.
3. Sundar, Shyam.. "Leishmaniasis." Harrison's Principles of Internal Medicine, 20eEds. J. Larry Jameson, et al. New York, NY: McGraw-Hill,
, http://accessmedicine.mhmedical.com/content.aspx?bookid=2129&sectionid=1920271