Opportunistic Mycoses, Subcutaneous Mycoses, Superficial Dermatophytes Flashcards
(57 cards)
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
