Fungi Flashcards
Cutaneous mycoses
Dermatophytes that infect the epidermis.
Secrete the enzyme keratinase → utilize keratin (main structural component of hair, skin, nails) as their energy source
Spread: human-human, animal- human via contact with infected skin scales remember Pat always saying she’s expecting ringworm because of her new puppy
Ex: Microsporum, Trichophyton, and Epidermophyton—cause tinea infections: scaling of the skin, loss of hair &/or crumbling of nails
Subcutaneous mycoses
Exploits an opening in skin after trauma (laceration, puncture) to gain entrance to the body. Infect the dermis, subcutaneous tissue, and bone.
Spread: soil / decaying vegetation – human, NOT via human-human think gardening, compost, & tropical climates
Ex: Sporothrix schenckii (ulcerated nodules along lymph path), Cladosporium (large, wartlike lesions)
Systemic mycoses
All dimorphic!!
Infections often asymptomatic, chronic pulmonary and dissemination to other organs rare.
Spread: Aerosolized spores, NOT human-human think specific geographic regions
Fungi in soil & feces of birds and bats → produce spore → airborne spores inhaled by human → spores germinate=primary pulmonary infection → disseminate to other tissues: CNS, bone, skin, GI, liver, spleen, lymph, bone marrow
Ex: Blastomyces, Histoplasma, coccidioides, paracoccidioides
Opportunistic mycoses
Subtype of systemic infection; symptoms more severe due to decreased immune status of host.
Spread: depends… Aspergillus= inhaled dust, Candida- normal flora overgrowth, Pneumocystis jiroveci- activation of dormant cells in lungs
Decreased Immunity: immunosuppressive meds (bone marrow or organ transplant), HIV, chemotherapy, diabetes, steroid therapy, co-infections
Infection because: immune system overwhelmed, medications decrease immune function, or other medications have killed off competing normal flora allowing yeast to overgrow.
Trichtophyton species
including Tinea manuum, Tinea pedis, Tinea capitis, Tinea cruris, Tinea corporis
*Tinea corporis / tinea cruris Tx: miconazole (Lotrimin), clotrimazole (Mycelex)
Parasitize epidermis including hair and nails, causing morbidity called superficialis.
Uses keratinase to break down the epidermis.
S/S: infection on epidermis.
-Skin lesions annular lesions from ringworm
-Scaling and macerations of affect area.
-Alopicia areata
-Itchiness
Diagnosis: Direct examination and fungal culture from lesions of skin, around hair and shavings from nails
Management:
Topical antifungal agents-thiocarbamates, imidazoles, allylamine and morpholines
Oral antifungal agents-ketoconazole, itraconazole, Fungusbinafine
Sporothrix schenckii
*Rose thorn
*Spopotrichosis (“rose thorn”)
Tx: itraconazole (Sporonox)
Pathogenesis: Skin laceration or puncture especially by rose thorn. Dissemination is common in immunocompromized pts.
S/S: Granulomatous ulcer at site of injury
Diagnosis: blood culture
Management: Itraconazole, Terbinafine
Histoplasma capsulatum
*Histoplasmosis
Tx: amphotericin B (Amphotec) (“Amphiterrible” - harsh drug)
Pathogenesis: Spores enter the lung and germinate into yeast-like cells. Macrophages engulf these cells. Pulmonary infection may be acute, chronic or fatal.
S/S: can be asymptomatic; often resembles TB (persistent cough, constant fatigue, weight loss, fever, hemoptysis, night sweats)
Diagnosis: Blood culture; Urinalysis for exo-antigen.
Management: Oral antifungal agent; Ketoconazole, Amphotericin B, Fluconazole etc.
Blastomyces dermatitidis
*Blastomycosis
*South Central/SE US
Pathogenesis: microspores enter the lung and germinate into thick-walled yeast-like cells; appear unipolar, broad-base buds. Dissemination is rare, but when it does happen, 70% of the time it goes from the lungs into the skin.
S/S: ulcerated granulomas of the skin
Diagnosis: isolation and culture of the fungus; exoantigen test.
Management: Oral antifungal agent; Ketoconazole, Amphotericin B, Fluconazole etc.
Candida species
*Oral or cutaneous candidal dermatitis, vaginal as well
Tx: nystatin (Mycostatin), fluconazole (Diflucan)
Cottage-cheese vaginal d/c
Thrush = oral candidiasis (okay in babies, bad in adults)
Pathophysiology: C. albicans most common species. Oral, vaginal, or systemic opportunistic infections- develop in immunocompromised states.
Symptoms: Oral- white raised plaques on oral mucosa and tongue.
Vaginal- White, cottage-cheese like discharge, itching and burning pain of vulva and vagina
Systemic- can affect G.I. tract, kidneys, liver, spleen (only very immunocompromised hosts)
Treatment - oral and vaginal- topically with nystatin or clotrimazole (azole oral/IV if severe- ketoconazole, fluconazole, itraconazole)
Systemic- Amphotericin B alone or with flucytosine
Aspergillis species
*Opportunistic
Pathogenesis: in immunocompromised hosts or patients treated with broad spectrum antibiotics. Most often causes lung infection, but can also affect eyes, ears, nasal sinuses, and skin. Can be acute or chronic nature, though a prior lung cavity lesion (a hyphal) is required for chronic lung infection to occur (i.e. prior tuberculosis), where a fungus ball will form but is non-invasive.
Symptoms: Acute: Pulmonary symptoms, can disseminate to brain, GI tract, and other organs. Often fatal. Chronic: Pulmonary symptoms, not severe.
Diagnosis and Treatment: Hyphal mass on X-ray, clinical sample pathology. V-shaped branches at 45 degree angle. Treatment with amphotericin B and surgical excision of infected tissue.
Pneumocystitis jiroveci
formerly P. carinii
*Opportunistic
*PCP pneumonia
Treat with trimethoprim / sulfamethoxazole (Bactrim/Septra)
*Predictable CXR pattern (see Antoinette’s slides)
Geographic distribution:
Blastomycosis
South Central US/SE US
Geographic distribution:
Coccidiomycosis
SW US
Geographic distribution:
Histoplasmosis
Ohio/Mississippi River Valley
Geographic distribution:
Paracoccidiomycosis
Central/South America
