Fungi
Organism Dermatophytes
➢ Trichophyton
➢ Epidermophyton
➢ Microsporum
Disease Cutaneous mycoses – superficial keratinized structure (skin, hair & nails)
Dermatophytosis (ringworm) (athlete foot & jock itch)
Onychomycosis – disease of the nails
Morphology Molds w hyphae
X dimorphic
Epidemiology Trichophyton is the most common cause of tinea capitis in children & endothrix infection
MOT Direct contact from person to person
Microsporum – spread from animals (dogs & cat)
Pathogenesis Chronic infection found in warm & humid areas of body
During onychomycosis, the nails become thickened, broken & discolored
Dermatophytid reaction
➢ Hypersensitivity cause vesicles in fingers
S&S Lesion
➢ Inflamed circular border
➢ W papules & vesicles surrounding clear area of normal skin
➢ Pruritic
Tinea capitis – head
➢ Favus (Trichophyton) (crust on scalp)
Tinea corporis – body
Tinea cruris – groin
Tinea pedis – foot
Tinea unguium – nails
Dx Scraping of skin/nail
➢ Placed in 10% KOH shows
➢ Septate hyphae
Culture w Sabouraud agar at room temp
Lesion exposed by UV light from Wood lamp
Tx Local antifungal cream (terbinafine, miconazole)
Oral griseofulvin
Oral itraconazole
Prognosis Relatively mild disease
Prevention Keep skin dry & cool
Organism Malassezia spp
Disease Cutaneous mycoses
Tinea versicolor (pityriasis versicolor)
Morphology Hyphae & yeasts
MOT Direct contact btw person to person
S&S Usually asymptomatic
Lesion
➢ Hypopigmented
➢ Slight pruritic
Dx Skin scraping in KOH
Tx Topic miconazole – recurrence can occur
Oral antifungal (fluconazole/itraconazole) – treat recurrences
Organism Sporothrix schenckii
Disease Subcutaneous mycoses
Morphology Dimorphic
➢ Mold – outside
➢ Yeast – inside human
MOT Inoculation by rose thron
RF ➢ Homeless
➢ Alcoholics
➢ Gardeners
S&S Local pustule/ulcer w nodules
➢ Painless
Complication Untreated lesion may wax & wane for years
Dx Round/cigar shaped budding yeast seen in microscopy
Culture in room temp shows hyphae
Tx Itraconazole (DOC)
Prevention Protect skin when touching plant, moss & wood
Organism Dematiaceous
➢ Fonscaea
➢ Phialophora
➢ Cladosporium
Disease Subcutaneous mycosis
Chromomycosis
, Morphology Dark colored hyphae
Epidemiology Common in tropic
MOT Inoculation thru trauma
S&S Wartlike lesion
➢ Crusting abscesses
Dx Dark brown, round fungal cells in leukocytes/giant cell
Tx Oral flucytosine/thiabendazole
Local surgery
Organism Coccidioides immitis & posadasii
Disease Systemic mycoses
Coccidioidomycosis / Valley fever / Desert rheumatism
Morphology Dimorphic
➢ Mold outside
➢ Spherule in tissue
In soils, it forms hyphae w arthrospores (very light & carried by wind)
Epidemiology Endemic in NA & SA
MOT Inhalation of arthrospores
Pathogenesis In the lungs, the arthrospores → spherules (filled w endospores)
➢ Upon rupture of wall, endospores are released & form new spherule
Fungi spread by direct extension/hematogenous spread
S&S Usually asymptomatic in lungs
Granulomatous lesion (commonly in bones & CNS)
Flu like symptom
➢ Fever
➢ Cough
➢ Arthralgis
Erythema nodosum
➢ Red & tender nodules (desert bumps)
➢ Over tibia & ulna
Complication Dissemination occurs in people w ↓CMI & IC
➢ Meninges – meningitis
➢ Bone – osteomyelitis
➢ Skin – nodule
Dx Skin test w fungal extract
➢ 5mm induration 48hrs post injection
➢ Stay + for 2-4 weeks
➢ Often – in patients w disseminated disease
Spherules seen microscopically in tissue
Culture w sabouraud agar at 25C shows septate hyphae w arthrospores
Serology testing IgM
ELISA
PCR
Tx X tx in asymptomatic/mild 1* infection
Fluconazole/itraconazole – for persisting lung lesion/mild disseminated disease
Amphotericin B – severe disseminated disease w bone lesion
Fluconazole (DOC) – meningitis
Prevention X vaccine
Avoid travelling to endemic area
Organism Histoplasma capsulatum
Disease Systemic mycoses
Histoplasmosis
Morphology Dimorphic
➢ Mold outside
➢ Yeast In tissue
Asexual spores
➢ Tuberculate macroconidia (thick wall & fingerlike projection)
➢ Microconidia (smooth walled spores)
Virulence Produce alkaline substance – survive in acidic phagolysosome & inactivate the degrative enzyme inside
MOT Inhalation of soil contaminated w birds dropping
Excavation of soil during construction
Exploration of bat infested cave
RF ➢ Construction worker
Pathogenesis After inhaled spores is engulfed by macrophages
➢ Oval budding yeast form develop in the cell
➢ Yeast survives phagolysosome
Systemic spread
➢ Esp to liver & spleen
S&S Usually asymptomatic
Small granulomatous foci heal by calcification
Acute infection
➢ Fever
➢ Headache
➢ Chills
➢ Cough
➢ Chest pain
Chronic infection
Organism Dermatophytes
➢ Trichophyton
➢ Epidermophyton
➢ Microsporum
Disease Cutaneous mycoses – superficial keratinized structure (skin, hair & nails)
Dermatophytosis (ringworm) (athlete foot & jock itch)
Onychomycosis – disease of the nails
Morphology Molds w hyphae
X dimorphic
Epidemiology Trichophyton is the most common cause of tinea capitis in children & endothrix infection
MOT Direct contact from person to person
Microsporum – spread from animals (dogs & cat)
Pathogenesis Chronic infection found in warm & humid areas of body
During onychomycosis, the nails become thickened, broken & discolored
Dermatophytid reaction
➢ Hypersensitivity cause vesicles in fingers
S&S Lesion
➢ Inflamed circular border
➢ W papules & vesicles surrounding clear area of normal skin
➢ Pruritic
Tinea capitis – head
➢ Favus (Trichophyton) (crust on scalp)
Tinea corporis – body
Tinea cruris – groin
Tinea pedis – foot
Tinea unguium – nails
Dx Scraping of skin/nail
➢ Placed in 10% KOH shows
➢ Septate hyphae
Culture w Sabouraud agar at room temp
Lesion exposed by UV light from Wood lamp
Tx Local antifungal cream (terbinafine, miconazole)
Oral griseofulvin
Oral itraconazole
Prognosis Relatively mild disease
Prevention Keep skin dry & cool
Organism Malassezia spp
Disease Cutaneous mycoses
Tinea versicolor (pityriasis versicolor)
Morphology Hyphae & yeasts
MOT Direct contact btw person to person
S&S Usually asymptomatic
Lesion
➢ Hypopigmented
➢ Slight pruritic
Dx Skin scraping in KOH
Tx Topic miconazole – recurrence can occur
Oral antifungal (fluconazole/itraconazole) – treat recurrences
Organism Sporothrix schenckii
Disease Subcutaneous mycoses
Morphology Dimorphic
➢ Mold – outside
➢ Yeast – inside human
MOT Inoculation by rose thron
RF ➢ Homeless
➢ Alcoholics
➢ Gardeners
S&S Local pustule/ulcer w nodules
➢ Painless
Complication Untreated lesion may wax & wane for years
Dx Round/cigar shaped budding yeast seen in microscopy
Culture in room temp shows hyphae
Tx Itraconazole (DOC)
Prevention Protect skin when touching plant, moss & wood
Organism Dematiaceous
➢ Fonscaea
➢ Phialophora
➢ Cladosporium
Disease Subcutaneous mycosis
Chromomycosis
, Morphology Dark colored hyphae
Epidemiology Common in tropic
MOT Inoculation thru trauma
S&S Wartlike lesion
➢ Crusting abscesses
Dx Dark brown, round fungal cells in leukocytes/giant cell
Tx Oral flucytosine/thiabendazole
Local surgery
Organism Coccidioides immitis & posadasii
Disease Systemic mycoses
Coccidioidomycosis / Valley fever / Desert rheumatism
Morphology Dimorphic
➢ Mold outside
➢ Spherule in tissue
In soils, it forms hyphae w arthrospores (very light & carried by wind)
Epidemiology Endemic in NA & SA
MOT Inhalation of arthrospores
Pathogenesis In the lungs, the arthrospores → spherules (filled w endospores)
➢ Upon rupture of wall, endospores are released & form new spherule
Fungi spread by direct extension/hematogenous spread
S&S Usually asymptomatic in lungs
Granulomatous lesion (commonly in bones & CNS)
Flu like symptom
➢ Fever
➢ Cough
➢ Arthralgis
Erythema nodosum
➢ Red & tender nodules (desert bumps)
➢ Over tibia & ulna
Complication Dissemination occurs in people w ↓CMI & IC
➢ Meninges – meningitis
➢ Bone – osteomyelitis
➢ Skin – nodule
Dx Skin test w fungal extract
➢ 5mm induration 48hrs post injection
➢ Stay + for 2-4 weeks
➢ Often – in patients w disseminated disease
Spherules seen microscopically in tissue
Culture w sabouraud agar at 25C shows septate hyphae w arthrospores
Serology testing IgM
ELISA
PCR
Tx X tx in asymptomatic/mild 1* infection
Fluconazole/itraconazole – for persisting lung lesion/mild disseminated disease
Amphotericin B – severe disseminated disease w bone lesion
Fluconazole (DOC) – meningitis
Prevention X vaccine
Avoid travelling to endemic area
Organism Histoplasma capsulatum
Disease Systemic mycoses
Histoplasmosis
Morphology Dimorphic
➢ Mold outside
➢ Yeast In tissue
Asexual spores
➢ Tuberculate macroconidia (thick wall & fingerlike projection)
➢ Microconidia (smooth walled spores)
Virulence Produce alkaline substance – survive in acidic phagolysosome & inactivate the degrative enzyme inside
MOT Inhalation of soil contaminated w birds dropping
Excavation of soil during construction
Exploration of bat infested cave
RF ➢ Construction worker
Pathogenesis After inhaled spores is engulfed by macrophages
➢ Oval budding yeast form develop in the cell
➢ Yeast survives phagolysosome
Systemic spread
➢ Esp to liver & spleen
S&S Usually asymptomatic
Small granulomatous foci heal by calcification
Acute infection
➢ Fever
➢ Headache
➢ Chills
➢ Cough
➢ Chest pain
Chronic infection
