Skin Pathogens-Fungal

Question 1

Malassezia Furfur

Answer 1

• Superficial mycosis-Outermost layers of skin _{^{(stratum corneum)}} & follicle
• NO immune reponse = NO destruction
• “Spaghetti & meatballs” _{^{(yeast & short mold)}}
• High risk: Young adults in tropics
• Needs lipids for growth
• Diagnosis: Microscopy-skin scrapping
• Treat: Spontaneous healing
• Keoconazole or Topical selenium sulfate
• Disease: “Pityriasis versicol”
• Lesions of irregular macules w/HYPO or HYPER pigmentation
• NO inflammation
• Interfere w/melanin production due by product=*Azeliac acid *
• Appearance on chest, upper back, arms, or abdomen

Question 2

Dermatophytes (Cutaneous)

Answer 2

• Monomorphic-Mold septate hyphae
• Macro-micro conida spores:
• _{^{<u>Microsporum</u> (Macro “velvetta shells”)}}
• _{^{<u>Trichophyton</u> (Micro-“Tear drops” or Macro-“Cigars”)}}
• _{^{<u>Epidermophyton</u> (Macro-Large “blunt ends”)}}
• Found in soil, animals _^(cats/dogs), humans
• High risk: Hot-humid climates w/exposure
• Ring worm/Tinea:
• _{^{Ring-shaped erythematous w/papules & vesicles}}
• _{^{Lesion can be prutitic (itchy)=Strong inflammatory response}}
• _{^{Tinea corporis=<u>Body</u>}}
• _{^{Tinea capitis=<u>Scalp</u>}}
• _{^{Tinea pedis=<u>Foot</u>}}
• _{^{Tinea barbae=<u>Beard</u>}}
• _{^{Tinea cruris=<u>Groin</u>}}
• _{^{Tinea unguium/Onychomyosis=<u>Nails</u>}}

Question 3

Dermatophytic Hair infections

Answer 3

• Ectothrix infection: Hyphae w/in the hair shaft w/ROUND spores on outer layer
• Endothrix infection: Hyphae & spores w/in the hair shaft
• Favic infection: “bubbly” empty air spaces inside hair
  
  • _{^{Hyphae & spores present <u>"honey comb"</u>}}
  • _{^{Causes hair loss}}
• Diagnosis:
• KOH prep to show conidia
• Wood’s lamp test=UV lamp 365 nm
  
  • _{^{<strong>Microsporum-(+)</strong>}}
  • _{^{<strong>Bacterial infections (coral red)</strong>}}
  • _{^{<strong>Pseudomonas (yellow)</strong>}}
    *

Question 4

Subcutaneous mycoses (Sprothrix schenckii)

Answer 4

• Dimorphic _{^{(mold in enviroment/Yeast @ body temp)}}
• Mold=Septate hyphae w/condida “rosette”
• _{^{In dish>wrinkled surface}}
• Yeast=Oval/elongated “cigar” shaped
• Found in soil, vegetation, rose thorns
• High risk: Forest employees, gardeners, florists
• Disease: _{^{“Lymphocutaneous sporotrichosis”}}
• Primary lesion-Chronic nodular/ulcerative
• Secondary lesion-Linear chain of PAINLESS subcutaneous nodules
• _{^{Draining lymphatics (stops @ axilla)}}
• _{^{Lesions may ulcerate-discharge PUS}}
• Treat: Oral K+idodide or Itraconazole

Question 5

Other Subcutaneous mycoses

Answer 5

• Chromomycosis: ^{<u><strong>_{"Phialophora Cladosporium"}</strong></u>}
• “Monomorphic”
• _{^{Pigmented molds found in soil & plants}}
• _{^{Enter through open wounds}}
• Disease: Slow granulomatous infection
• _{^{Tough wart like growth}}
• _{^{Highly destructive w/NO systemic infection}}
• Eumycotic mycetoma: _{^{<u>"Petriellium &amp; Madurella"</u>}}
• _{^{Found in tropics w/LOW rainfall}}
• _{^{Enters through open wound}}
• Disease: Localized chronic granulomatous
• _{^{<strong>Abscesses contain LARGE fungal hyphae</strong>}}
• _{^{<strong>Deep draining sinuses w/PUS</strong>}}
• _{^{<strong>Extension to muscle>fascia>BONE</strong>}}

Question 6

Candida Albicans general

Answer 6

• Yeast Fungus>Reproduces by budding
• “long germ tube”=^{_{Pseudohyphae (elongated yeast)}}
• THICK-walled chlamydoconidia
• Found in skin, mouth , rectum, vagina
• Endogenous infection due to off-balance w/Normal flora
• _{^{PH change (low)}}
• _{^{Increased sugar}}
• _{^{Antibiotic treatment}}
• Exogenous _{^{assoc w/medical intervention-<u>(blood stream infections)</u>}}
• _High risk: _
• Diabetes
• Immunocompromised
• Moist/warm areas on body

Question 7

Candida Albicans disease

Answer 7

• Cutaneous & Mucosal Candidiasis:
• Cutaneous= _{^{folliculitis/Erythema Vesicles}}
• Occurs moist warm parts or folds _{^{(below breast/Butt crack)}} aka “diaper rash”
• Between digits/Nails (onychomycosis)
• Ex. Dish cleaner contact w/sugar sols
• Mucocutaneous=^{_{White pseudomembranous lesions}}
• Oral candidiasis “Thrush”
• Can extend down esophagus>Intestine
• Genital tract-Women
• Systemic candidiasis=Bronchi, lungs, GI, Septicemia, endocarditis & meningitis
• Diagnose: _{^{direct swab will demonstrate Yeast w/Pseudohyphae}}
• Germ tube test: _{^{Inoculate into animal serum @ body temp=develop elongated tubes}}
• Treat: Imidazoles, nystatin
• ^{_{Amphotericin B <u>(systemic)</u>}}