Fungi

Question 1

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

Answer 1

superficial mycoses

Question 2

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

Answer 2

black piedra

Piedra hortae

Question 3

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

Answer 3

white piedra

Trichosporon beigelii

Question 4

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

Answer 4

Tinea nigra

Exophiala werneckii

Question 5

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

Answer 5

Tinea/pityriasis versicolor

Malassezia furfur

Question 6

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

Answer 6

Cutaneous Mycoses

Question 7

Usually involves trauma for entry

Some infections may not respond to antifungals and require surgery

Answer 7

Subcutaneous mycoses

Question 8

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

Answer 8

Lymphocutaneous sprortrichosis

Sporothrix schenckii

Question 9

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

Answer 9

Chromoblastomycosis

Fonsecaea or Cladosporium spp.

Question 10

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

Answer 10

Eumycotic mycetoma
Pseudallescheria boydii
Madurella grisea

Question 11

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

Answer 11

primary fungal pathogens that cause deep tissue infections

Question 12

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

Answer 12

Blastomycosis

Blastomyces dermatitidis

Question 13

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

Answer 13

Coccidiomycosis

Coccidiodes immitis

Question 14

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

Answer 14

Histoplasmosis

Histoplasma capsulatum

Question 15

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

Answer 15

Paracoccidiomycosis

Paracoccidiodes brasiliensis

Question 16

Usually affect immunocompromised host with either neutrophil or T cell defect

Answer 16

opportunistic fungal pathogens that cause deep tissue infection

Question 17

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

Predisposition for invasion: neutropenia (ANC)

Answer 17

Candidiasis

Candida spp.

Question 18

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

Aspergilloma
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

Answer 18

Aspergillosis

Aspergillus spp.

Question 19

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

Answer 19

Zygomycosis

Zygomycetes: Mucor, Rhizopus, Absidia

Question 20

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

Answer 20

Cryptococcus

Cryptococcus neoformans

Question 21

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

Answer 21

Pneumocystis jirovecii