Opportunistic Mycoses, Subcutaneous Mycoses, Superficial Dermatophytes Flashcards
What type of patients are at risk for opportunistic mycoses
HIV/AIDS Cancer (e.g., leukemia) Diabetes Immunosuppression -->Post-transplant -->Corticosteroids
List of opportunistic mycoses
Candida Albicans Aspergillus Cryptococcus Neoformans Zygomycetes (mucor/rhizopus) Pneumocystis jiroveci (PCP)
Morphology of candida albicans
Dimorphic: Budding yeast (pseudohyphae that don’t branch); germ tubes
Clinical presentation of candida albicans in a normal host
- Vulvovaginal candidasis: “yeast infection” (think post antibiotic treatment)- White and Curdlike
- Cutaneous: Diaper Rash in Babies, Skin fold infections (intertriginous areas) in obese patients and diabetics, Nail plate infections
- Esophagus: Candida esophagitis (oral Thrush) mostly immunocompromised patients, but also occurs in Diabetics and people on chronic steroids (asthma and COPD)
oral thrush vs oral hairy leukemia
Opportunist infectionss of candidal oral thrush (dorsal surface of tongue) and EBV oral hairy leukoplakia (lateral surfaces of tongue).
Diagnosis of candida albicans
KOH test preformed on direct biopsys (can visualize Germ tube), blood culture
Epidemiology of candida albicans
Women (esp. post-abx); immunocompromised; commensal organism
Clinical presentation of candida albicans in an immunocompromised host
Immunocompromised Host (Cell mediated immunity)-> Think Neutropenia
- Mucocutaneous: Oral Thrush in AIDS, Transplant, chemotherapy patients
- Systemic Infection: Can seed almost any organ! (Catheters –> candidemia, parenteral nutrition, broad spectrum antibiotics are risk factors and can occur in immunocompetent as well as immunosuppressed)
Aspergillus morphology
Spore-bearing, thin septate hyphae, acute-angle branching. Fruiting head may be seen under lactophenol blue stain.
Acute Angle Aspergillus. 45 degree branching.
Right angle branching: Compare morphology with zygomycetes (mucor/rhizopus)
Virulence factors aspergillus
Proteases, toxins (aflatoxin)
Clinical presentation of aspergillus
Non-immunocompromised:
Allergic bronchopulmonary aspergillosis (ABPA) (Asthma or CF);
aspergilloma (non-invasive fungus ball in preformed/TB lung cavities);
In immunocompromised:
- -> invasive pulmonary, systemic dz (neutropenics); Angioinvasive –> HEMOPYTISIS (coughing up blood)
- -> primary cutaneous infections; hematogenous spread
“Aspergillus = Acute Angle, Aspergilloma, Angioinvasion, ABPA”
Diagnosis of aspergillus
Biopsy, culture, lactophenol blue staining
Epidemiology of aspergillus
Immunocompromised hosts. Commonly found in the environment. #1 most common invasive mold in the world
Treatment of aspergillus
Voriconazole, Amphotericin B. Immune reconstitution important for recovery.
Cryptococcus Neoformans morphology
Monomorphic, Encapsulated yeast
Cryptococcus Neoformans virulence factors
Capsule (evade phagocytosis, deplete complement), phenotypic switching (change in capsule, cell wall), melanin (antioxidant, inhibit antifungal & Ab-mediated phagocytosis)
Cryptococcus Neoformans diagnosis
PAS & silver stain, INDIA INK ON CSF (Halo/soap bubbles), Serology, Latex agglutination (is more specific than serology)
Cryptococcus Neoformans epidemiology
Inhaled; Environmental (soil, pigeon droppings); immunocompromised (AIDS/defects in cellular immunity, transplant, pregnancy)
Cryptococcus Neoformans treatment
Amphotericin B – drug of choice for cryptococcal meningitis +/- flucytosine
Fluconazole – mild to moderate pulmonary cryptococcosis; maintenance therapy for cryptococcal meningitis/should avoid using during first trimester of pregnancy
Cryptococcus Neoformans clinical presentation
Respiratory (main route of entry), dissemination, meningitis (immunocompromised); may be asymptomatic
Zygomycetes (mucor/rhizopus) morphology
Wide, non-septate, ribbon-like hyphae with wide (right-angle) branching (vs acute branching of aspergillus).
Genera include Rhizopus (> 98% of cases) and Mucor
Zygomycetes (mucor/rhizopus) virulence factors
Have ketone reductase, an enzyme that allows them to thrive in high glucose, acidic conditions. Spore-forming. Able to ANGIOINVADE.
Zygomycetes (mucor/rhizopus) clinical presentation
Mucormycosis: angioinvasion brain tissue destruction leading to necrosis;
Primary cutaneous skin infections (BLACK NECROTIC ESCHAR) from direct inoculation
Common Clinical: Rhinocerebral zygomycosis-> Direct infection from airborne spores in the paranasal sinuses-> Black Nasal discharge (Black necrosis)
Zygomycetes (mucor/rhizopus) epidemiology
IMMUNOCOMPROMISED hosts, associated strongly with DIABETES (hyperglycemia) and DKA, Deferoxamine therapy (Fe chelator; used by Rhizopus as siderophore), NEUTROPENIA, and bone marrow transplants
Cutaneous infections may follow surgery, burn wounds, trauma/ have been associated with Non-sterile bandages
Zygomycetes (mucor/rhizopus) treatment
Surgical debridement is key, Amphotericin B, Posaconazole
Pneumocystis jiroveci (PCP) morphology
Cup shaped fungi, “crushed ping-pong ball”
Pneumocystis jiroveci (PCP) diagnosis
Methenamine Silver stain or Direct Fluorescent Antibody of sample – sputum or bronchiolar lavage
Cannot be grown in culture
Pneumocystis jiroveci (PCP) virulence factors
Attachment to pulmonary epithelial cells
Pneumocystis jiroveci (PCP) clinical presentation
Diffuse interstitial pneumonia with plasma cell infiltrates, hypoxemia (low pO2); CXR show diffuse/patchy bilateral, alveolar infiltrates – “ground glass” appearance. Asymptomatic in immunocompetent.
Pneumocystis jiroveci (PCP) epidemiology
Immunocompromised hosts. Most common opportunistic infection in AIDS patients in US (CD4+
Pneumocystis jiroveci (PCP) treatment and side effects
TMP-SMX (also used as prophylaxis in patients with CD4+
Most common human fungal infections
- Tinea cruris is pruritic infection of groin.
- Pityriasis versicolor is a superficial dermatophyte infection characterized by hypo or hyperpigmentation.
What causes athlete’s foot/ what is the not common name of athlete’s foot?
Various topical dermatophytes. Tinea pedis.
Diagnosis of athlete’s foot?
Inspection
Treatment of athlete’s foot?
Topical antifungals (miconazole, tolnaftate)
What causes nail fungus/what is medical term for nail fungus?
Trichophyton rubrum.
Fungal onychomycosis .
Diagnosis of nail fungus
Inspection
Treatment of nail fungus
Oral terbinafine (resistant to topicals)
What causes ringworm, what is the medical term for ringworm
Various topical dermatophytes, tinea corporis
Diagnosis of ringworm
Inspection
Treatment of ringworm
Topical antifunguls
hypo/hyperpigmentation, what is the cause and medical term
Cause: Malassezia furfur.
medical term: Pityriasis versicolor
Diagnosis of Pityriasis versicolor
Scraping stained with KOH shows
yeast and hyphal forms (“spaghetti & meatballs”)
Treatment of pityriasis versicolor
Topical Antifungals
Superficial Dermatophytes
Trichophyton, Malassezia
Subcutaneous Mycoses
Sporothrix, Madurella
Madurella Grisea clinical
Chronic, slowly progressing ulcerative lesions on the foot . Subcutaneous infection caused by various species of fungi including Madurella mycetomatis and Madurella grisea. May see coarse black fungal granules in discharge
Madurella Grisea pathogenesis
Found in the soil, enters through abrasions in the skin.
Madurella Grisea diagnosis
Biopsy
Madurella Grisea epidemiology
Farmers, People who don’t wear shoes.
Madurella Grisea treatment
Surgical debridement, amputation, voriconazole, posaconazole
Sporothrix schenckii morphology
Dimorphic, cigar-shaped, budding yeast.
Sporothrix schenckii clinical
Sporotrichosis – local pustules and ulcers – spreads along draining lymph nodes (skip lesions); ascending lymphangitis; little to no systemic illness.
Sporothrix schenckii diagnosis
Biopsy, culture.
Sporothrix schenckii epidemiology
Lives on vegetation. Associated with gardening (particularly rose thorns). Rose gardener’s disease.
Sporothrix schenckii treatment
Itraconazole.
Sporothrix schenckii pathogenesis
Inoculation occurs in distal extremity with lymphangitic spread characteristically up arm.
