Oh’s (73) - Fungal Infections Flashcards
The difference between yeasts and moulds
Yeast - unicellular
Mould -multicellular
Types of Invasive Fungal Infections
1) Primary Mycoses
Occur in immunoCOMPETENT Endemic in places where spores are abdundant Agent has innate virulence that overcomes normal host defences
2) Secondary / Opportunistic
Less innate virulence But occur in immunocompromised, cancer, burns, HIV, Abx use
Treatment options for fungal disease
Polyenes (Amphotericin B)
Azoles
Imidazoles and triazoles
(Voriconazole)
Echinocandins
Flucytosine
Mechanism of action of polyenes
Amphotericin B
Bind to Ergosterol in fungal wall
Cell death
Mechanism of action of Azoles
Inhibit ergosterol SYNTHESIS
Fungo-static
However - voriconazole can be fungicidal to aspergillus
Mechanism of Echinocandins
Inhibit b-glycol synthesis
Cell wall becomes unstable
Fungicidal to yeasts
Fungostatic to asperigiullius
Mechanism of flucytosine
Converts to 5 flurouracil
Incorporates into yeast RNA
Better with yeasts than moulds
Other therapeutic options of fungal infections
Folic acid inhibition in Pneumocystosis
Types of Priamry Mycoses
1) Blastomycosis (Gilchrist Disease) - Amphotericin for 12 months with Itraconazole step down
2) Coccidiodomycosis
3) Cryptococcous
4) Histyoplasmosis
5) Paracoccidiomnycosis
Dispositions to Opportunistic Mycoses
Use of CVP lines Cavity surgery Neutropenia Steroids HIV Disseminated malignancy ICU > 7 days TPN Malnutrition Burns Organ transplant
Types of Opportunistic Mycoses
Aspergillosis Candida Cryptococcosis Penicillinosis Pneumocystosis Zygomycoses
Examples of Aspergillosis
Aspergillus genus of moulds
Fumigatus
Flavus
Niger
Patients at risk of aspergillosis
Immunosuppresed - Chemo, HIV, steroids, transplant
ImmunoCOMPETENT - Liver disease, pancreatitis, DM
Chronic Lung disease on low dose steroids
Define pulmonary aspergillosis
Spectrum from
Localised Simple Aspergilloma (may lead to BPF or bleeding through erosion() To Allergic Broncopulmonary Aspergillosis (asthma /CF) To Progressive multi site pulmonary disease with extensive destructive cavitation
Leads to systemic infection —> brain and solid organs
Diagnosis Aspergillosis
Positive cultures/microscopy from samples
Focal lesions on CT chest/brain (halo sign)
Positive PCR - fluids (BAL), faster than MC&S, 90% sense/spec
Galactomannan
b-D-glucans in BAL or serum