Fungi-Yeasts, Molds, Dimorphics Flashcards
- Can cause superficial, localized or systemic infections.
- Are free-living in nature and are usually acquired from the environment
- Cause damage by eliciting inflammation or by direct invasion of tissue
Pathogenic Fungi
Where do pathogenic fungi live?
(exogenous)
- Decaying Vegetation - Aspergillus
- Pigeon Droppings - Crytococcus neoformans
- Soil wih Bird and Bat Excreta - Histoplamsa capsulatum
- Rose and Barberry Thorn - sporothrix Schenckii
Where do pathogenic fungi live?
(endogenous)
- Skin and GI tract - Candida
- Human skin rich in sebaceous glands - Malassezia
Primary Pathogenic Fungi Include…
- Blastomyces dematitidis
- Coccidioides Immitis
- Histoplamsa Capsulatum
- Spopthrix Schenckii
Opportunistic pathogenic fungi include…
- Aspergillus species
- Candida species
- Pneumocystis jirovecii
Compromised host defense that results in defective or low number of neutrophil may experience fungal invasion. What fungi are most likely responsible in this case?
Candida
Aspergillus
Mucor
Descibe superficial mycoses.
Limited to the outermost layers of the hair or skin. Mild infections with no or minimal inflammation.
What are some examples of Superficial Mycoses?
- Black Piedra
- White Piedra
- Tinea Nigra
- Tinea or pityriasis versicolor
What is this and how would you treat it?
This is an image of white piedra, a superficial mycosest, that causes white granules on hair shafts of genital and beard areas due to TRICHOSPORON BEIGELII
TX = shaving all hair; does not recur
How would you diagnose a superficial mycoses infection?
Wet monut of hair or skin with 10% KOH
What is this and how would you treat it?
Black Piedra, mild infection with no/minimal inflammation, superficial mycoses, that produces hard,gritty brown-black concentration on sclap hair due to PIEDRAIA HORTAE
TX= Shaving all hair; don’t recur
What is this and how would you treat it?
Tinea Nigra- a mild infection with no/minimal inflammation, superficial mycoses, that produces brown-black macules on palms>soles due to EXOPHIALA WERNECKII
TX = topical keratolytic agent or azole
What is this and how would you treat it?
Tinea or pityriasis versicolor, superficial mycoses, a mild infection with no/minimal inflammation that produces hyper- and hypo-pigmented confluent scaly macules on torso due to MALASSEZIA FURFUR
TX= Selenium sulfide sulfide 2.5% solution
Other keatolytic agents
Topical azole
How would you diagnose Cutaneous mycoses ?
Wet mount using 10% KOH with skin hair or nail scraping
Culture in media with cycloheximide and cloramphenicol to inhibit overgrowth of saprobic fungi and bacteria
Describe cutaneous mycoses.
Infect the keratinized tissues (epidermis, hair and nails) may elicit a cellular immune respons.
Consist of dermatophytes belonging to 3 genera:
- Microsporum
- Trichophyton
- Epidermophyton
What is this and how would you treat it?
Tinea Capitis, cutaneous mycoses
an infection of the keratinized tissue that may elicit a cellular immune response.
TX= oral terbinafine
itraconazole
ketoconazole & griseofulvin (rarely used)
What is this and how would you treat it?
Tinea Corporis, cutaneous mycoses
An infection of the keratinized tissues that may elicit a cellular immune response.
TX= topical terbinafine
naftifine
topical azoles
What is this and how would you treat it?
“Jock Itch” Tinea cruris, cutaneous mycoses
An infection of the keratinized tissues that may elicit a cellular immune response.
TX= topical terbinafine
naftifine
topical azoles
What is this and how would you treat it ?
Tinea Unguium (nails), cutaneous mycoses
An infection of the keratinized tissues that may elicit a cellular immune response.
TX= topical terbinafine
naftifine
topical azoles
What is this and how would you treat it?
Tinea Barbae, cutaneous mycoses
An infection of the keratinized tissues that may elicit a cellular immune response.
TX= topical terbinafine
naftifine
topical azoles
What is this ?
Trichophyton mentagrophytes
Dermatophyte of the Trichophyton genre of cutaneous mycoses
What is this
Microsporum Gypseum in hair shaft
Dermatophyte of the Microsporum genre of cutaneous mycoses
Describe Subcutaneous Mycoses.
Involves the dermis and subcutaneous tissue. Usually involves trauma for entry
Some infection may not respond to antifungal therapy and my need surgery.
Includes the following disease:
- Lymphocutaneous sporotrichosis
- Chromoblastomycosis
- Phaeohyphomycosis
- Eumycetoma mycetoma
What is this?
DSZ= Lymphocutaneous Sporotrichosis
Causitve agent= Sporothrix Scheneckii (Dimorphic fungus)
Entry= implanted into skin by trauma
Clinical Manifestation= Nodule at site of entry ulcerates and form other nodules along lymphatic drainage channels
A patient who presents like this. what would you do to diagnose and treat the patient? What would you see?
This patient ahs Lymphocutaneous sporotrichosis caused by the dimorphic fungus sporothrix schenckii.
Diagnose = culuture, You will see white mould that will darken to brown black with prolonged incubationat 25C and cigar shaped yeasts on biopsy
TX= Saturated solution of KI (potassium iodide)
Itraconazole
Amphotericin B
What is this ?
Chromoblastomycosis, a subcutaneous mycoses
Causitive agent = Fonsecaea or Cladosporium
A warty, vegatative, caulifower like lesion.
How would you diagnose and treat Chromoblastomycosis?
Diagnosis = histophathology with epithelil cell hyperplasia and copper colored spherical fungi, sclerotic or Medlar bodies
Treatment = surgical excision or cryosurgery, intraconazole, terbinafine
What is this ?
Eumycotic mycetoma, subcutaneous mycoses
Causative agent = Pseudallescheria boydii and Madurall grisea (and also actinomyctes and bacteria)
Purulent drainae from sinus tracts
A patient has eumycotic mycetoma. How would you diagnose and treat this?
Diagnosis = histopathology of grains from sinus tracts show fungal elements; culture
Treatment = surgical excision or amputation for extensive dsz with wide margins to prevent recurrence
* limited success with itraconazole and ketoconazole
Describe Deep Tissue Fungal Infections
These infections are acquired from endogenous or environmental sources.
May invade the organs of the entire body.
Enter the bloodstream and disseminate.
This group of infections includes:
- Blastomyces dermatitidis
- Aspergillus species
- Coccidioides immitis
- Histoplasms capsulatum
- Candida species
- Cryptococcus neoformans
Describe Primary Fungal Pathogens.
Infection that can affect a healthy host.
Often have geographic prdilection
Are inhaled and may cause chronic lung infection similar to TB
May cuase system or disseminated disease in the immunocompromised host
Include:
- Blastomyces dermatitidis
- Coccidioides immitis
- Histoplasma capsulatum
- Paracoccidioides brasiliensis
Blastomyces dermatitidis
Dimorphic fungus
Entry = inhaled spores enter the lund
Dogs may develop similar diseases
Clinical manifestations =
Primary lung infection amy be unapparent
Chronic pneumonia and cavity
Disseminate to skin, bone, and urogential tract
What is this and how would you treat it?
Blastomyces dermatitidis ( a primary fungal pathogen)
TX= itraconazole better then fluconazole for lung infection; ketoconazole rarely used
Amphotericin B for azole failures and disseminated infection
These lab findings would confirm diagnosis of what primary fungal infection.
Blastomyces dermatitis
These histological findings would suggest what primary fungal infection?
Balstomyces Dermititdis
Coccidioidomycosis
Dimorphic fungus
Entry = inhaled spores enter lung
Clincial manifestations: Symptomatic lung infection in 40%
Chronic infection may result in lung cavity
Disseminates to CNS, Bone, Skin
Predispositions for dissemination: AIDS, Dark skinned individuals, pregnancy
Coccidioides Immitis Diagnosis would include:
Diagnosis:
Culture
Biopsy
Complement fixation antibody: for disseminated disease and relapse
Describe Coccidioides immitis pathology.
endospores (2-5micron) within spherules seen in pyogenic and granulomatous reaction
How would you treat Coccidioides immitis?
Fluconazole better than itraconzale for lung infection; ketoconazole rarely used
Amphotericin B for azole failures and disseminated inection
How would you treat this ?
This is coccidioides immitis.
Fluconazole better than intraconazole for lung infection: ketoconazole. Amphotericin B for azole failures and disseminated infection
Histoplasma capsulatum
Dimorphic fungus
Found in soil contaminated by bird or bat excreta
Entry = inhaled spores lung
Clinical manifestations =Primary lung infection may be symptomatic in 5%
Lung lesion heals with calcification and fibrosis
Chronic pneumonia and lung cavity
Disseminate via bloodstream to all organs, esp in immunocompromised host
Describe the pathology of Histoplasma capsulatum.
phasocytosed ovoid yeast found within monocytes and histiocyte; granulomatous reaction
How would you treat this patient?
This patient has disseminated histoplasmosis.
TX = itraconazole better than fluconazole for lung infection; ketoconazole rarely used.
Histoplasma capsulatum
Histoplasma capsulatum
Histoplasma capsultum
“yeast like vessicle like mariner’s wheel”
Paracoccidioides brasiliensis
Disseminated Blastomyces
Disseminated Coccidioidomycosis
Dimorphic fungus
Found in soil contaminated by bird or bat excreta
Entry: inhaled spores lung
Clinical manifestations:
» Primary lung infection may be symptomatic in 5%
» Lung lesion heals with calcification and fibrosis
» Chronic pneumonia and lung cavity
» Disseminate via bloodstream to all organs, especially in immunocompromised host
Histoplasma capsulatum
Pulmonary Histoplasmosis
Disseminated Histoplasmosis
