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Flashcards in Fungi Deck (21):

limited to the outermost layers of hair/skin
mild infections with no/minimal inflammation
diagnosed with wet mount of hair/skin with 10% KOH

superficial mycoses


superficial mycosis
hard, gritty brown/black concretions on scalp hair
shave hair, will not recur

black piedra
Piedra hortae


superficial mycosis
Soft, white granules on hair shafts of genital and beard areas
Shave hair, will not recur

white piedra
Trichosporon beigelii


superficial mycosis
Brown/black macules on palms > soles
Topical keratolytic agent or azole

Tinea nigra
Exophiala werneckii


superficial mycosis
Hyper- and hypo-pigmented confluent scaly macules on torso
Selenium sulfide solution/keratolytic agent, topical azole for recurrence
Diagnosis requires oil supplementation in culture

Tinea/pityriasis versicolor
Malassezia furfur


Infect keratinized tissues (epidermis, hair, nails) may elicit cellular immune response
Tinea capitis (head); tinea barbae (beard); tinea corporis (body); tinea cruris (perineum = jock itch); tinea pedis (feet = athletes foot); tinea unguium (nails)

dermatophytes: Microsporum, Trichophyton, Epidermophyton

diganosis: Wet mount in 10% KOH – skin, hair, nail scraping
Culture inmedia with cyclohexamide and chloramphenicol (inhibit bacteria)

treatment is oral or topical antifungal

Cutaneous Mycoses


Usually involves trauma for entry
Some infections may not respond to antifungals and require surgery

Subcutaneous mycoses


subcutaneous mycosis
Dimorphic fungus implanted into skin by trauma
Nodule at site of entry ulcerates and forms other nodules along lymphatics
Dx: culture, white mold will darken to brown/black with prolonged incubation at 25 degrees; cigar shaped yeasts on biopsy
Rx: antifungal

Lymphocutaneous sprortrichosis
Sporothrix schenckii


subcutaneous mycosis
Warty, vegetative, cauliflower-like lesions
Dx: histopathology with epithelial cell hyperplasia and cooper colored spherical fungi in sclerotic or Medlar bodies
Rx: surgical excision, cryosurgery, antifungals

Fonsecaea or Cladosporium spp.


subcutaneous mycosis
Similar to mycetoma caused by Actinomycetes
Purulent drainage from sinus tracts
Dx: histopathology of grains or sulfur granules from sinus tracts showing fungal elements; culture
Rx: surgical excision or amputation for extensive disease, wide margins to prevent recurrence; limited success with antifungals

Eumycotic mycetoma
Pseudallescheria boydii
Madurella grisea


Dimorphic fungi, can affect healthy hosts, often have geographic predilection
Inhaled and may cause chronic lung infection similar to TB
May cause systemic or disseminated disease in the immunocompromised

primary fungal pathogens that cause deep tissue infections


primary fungal pathogens that cause deep tissue infections
Mostly seen in the Eastern and Midwest US

Inhaled spores enter the lung and cause primary lung infection that may not be apparent
Chronic pneumonia and cavity
Dissemination to skin, bone and GU tract

Broad base budding yeast within microabscesses and granulomas
Rx: antifungals

Blastomyces dermatitidis


primary fungal pathogens that cause deep tissue infections
Mostly seen in SW US and Mexico

Inhaled spores enter lung:
Symptomatic ling infection in 40%
Chronic lung infection may cause lung cavity
Dissemination to CNS, bone, skin

Predispositions for dissemination: AIDS, dark-skin, pregnancy

Dx: culture (can be acquired via lab handling), biopsy, complement fixation Ab for disseminated disease and relapse
Endospores within spherules seen in pyogenic and granulomatous reaction
Rx: antifungals

Coccidiodes immitis


primary fungal pathogens that cause deep tissue infections
Mostly seen in the Midwest US (Mississippi River Valley)
Found in soil contaminated by bird or bat excreta, entry via inhaled spores

Primary lung infection may be symptomatic in 5%
Lung lesion heals with calcification and fibrosis
Chronic pneumonia and lung cavity
Hematogenous dissemination in immunocompromised host (gingival ulceration)

Predisposition for dissemination: AIDS, chronic corticosteroid therapy

Dx: phagocytosed yeasts seen on Giemsa stain, culture (can be acquired by lab handling) (macro and microconidia at 25 degrees), biopsy, urinary antigen for disseminated disease, complement fixation antibody (cross reaction especially with B. dermatitidis)
Phagocytosed ovoid yeasts found within monocytes and histiocytes; granulomatous reaction
Rx: antifungals

Histoplasma capsulatum


primary fungal pathogens that cause deep tissue infections
Endemic in Central and South America

Inhaled spores enter the lung
Can disseminate to mucus membranes (GIT and skin) – mucocutaneous infection, intestinal ulceration

Yeast resembling a mariner’s wheel
Rx: antifungals

Paracoccidiodes brasiliensis


Usually affect immunocompromised host with either neutrophil or T cell defect

opportunistic fungal pathogens that cause deep tissue infection


opportunistic fungal pathogens that cause deep tissue infection
Commensal on skin and within GIT, most infections are endogenous

Predisposition for invasion: neutropenia (ANC)

Candida spp.


opportunistic fungal pathogens that cause deep tissue infection
Ubiquitous mold in the environment, spores are inhaled into lungs
Allergic bronchopulmonary aspergillosis
Asthma, central bronchiectasis, immediate skin hypersensitivity to aspergillus antigens, aspergillus precipitins

Fungus ball in old lung cavity, may cause severe hemoptysis

Invasive aspergillosis
Affects lungs/sinuses and causes systemic infection
May cause infarctions (eyes, CNS, skin, bone)

Dx: culture and biopsy
Narrow septate hyphae with acute angle branching; predilection for blood vessels causes thromboses and infarction
Rx: antifungals; response to therapy for invasive infections depends on neutrophil function return

Aspergillus spp.


opportunistic fungal pathogens that cause deep tissue infection

Predispositions: DM with acidosis, trauma and burns, neutropenia, chelating agent use

Rhinocerebral infection: DKA
Pneumonia: neutropenia
Skin infections: burn and trauma

Dx: culture and biopsy
Broad non-septate or coencocytic hyphae with right angle branching; predilection for blood vessels causes infarction
Rx: surgical debridement and antifungals; sinus infection response to therapy depends on correction of acidosis, lung infection depends on return of neutrophils

Zygomycetes: Mucor, Rhizopus, Absidia


opportunistic fungal pathogens that cause deep tissue infection

Ubiquitous yeast worldwide; serotypes A and D (neoformans) in pigeon excreta, serotype B (gatti) in debris under red gum tree

Predispositions: AIDS, prolonged steroids, lymphoma, none in 50% (before AIDS)

Pneumonia, lung cavity, meningitis, dissemination to skin, eye, bone, and prostate

Dx: India ink defines capsule on wet mount; culture (bird seed agar, Sabourad’s agar)sputum, blood, CSF, urine; biopsy and stain with mucicarmine stains (capsule); polysaccharide antigen in blood and CSF (cross reaction with T. beigelii)
Rx: antifungals; chronic suppressive therapy needed for AIDS patients

Cryptococcus neoformans


opportunistic fungal pathogen that causes deep tissue infection

dark ovoid sporozoites within cysts on silver stain
often affects AIDS patients and infants

cyst is inhaled by most people in childhood causing a mild pneumonia and latent infection in the lungs

immunocompromised host: reactivation, uncontrolled growth, inflammatory response cause pneumonia

pneumonitis, pneumothorax

Pneumocystis jirovecii