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59 Cards in this Set
- Front
- Back
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plasma membrane of fungi contain what? importance of this?
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ergosterol instead of cholesterol, ergosterol is an antibiotic target, but it is similar to cholesterol so it may affect us a bit as well
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what makes up the fungi cell wall?
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chitin - no drugs against it yet
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what are the dimorphic phases of fungi and when do they usually exist?
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yeast and hyphae (molds), yeast is usually in body at 37 degrees, but turns to hyphae at 25 C. note a mass of mold is called mycelium
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types of growth patterns/morphology of yeast form?
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fission, budding to form blastoconidia, and germ tube to form pseudohyphae
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describe the agents of mycotoxicosis.
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ergot alkaloids (inflammation, necrosis, smooth muscle contraction, vasoconstriction), psychotropic agents (shrooms), and aflatoxins (carcinogen)
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what are the 4 primary fungal pathogens and what are their characteristics?
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blastomycosis, histoplasmosis, coccidiomycosis, paracoccidiomycosis; adherence, grow at 37 C, cell wall mannans, proteases, binds to ECM, resistance to phagocytosis, survives in macs.
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describe the antifungal polyenes and the two most important ones.
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all made by streptomyces, cyclic macrolide lactones, binds ergosterol in preference to cholesterol but can bind cholesterol in high concentrations, can cause poors in membrane or oxidative events on membrane. Amphotericin B is given topically or IV, broad spectrum, kidney toxicity and system side effects, mainly used for systemic infections. Nystatin works similarly to amphotericin
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describe the general properties of the azole derivatives.
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broad spectrum, large group, commercially available, inhibit synthesis of ergosterol via inhibiting a synthesizing enzyme.
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name and descirbe the 4 azole derivative drugs.
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ketoconazole (imidazole rest ar triazoles): limited spectrum, toxic, second line agent. flucanazole: good oral bioavailability, low toxicity, better spectrum of action, treats candidiasis, cryptococcus, and coccidiomycosis. itraconazole: broad spectrum, 1st line for non-meningeal histoplasmosis, blastomycosis, and paracoccidiomycosis, second line for aspergillosis. voriconazole: broad spectrum, primary indication for aspergillosis and massive candidiasis.
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describe the echinocandins.
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lipopeptides that inhibit cell wall synthesis, names are caspofungin, mica fungin, and anidulafungin, caspo approved for invasive aspergillosis and candidiasis, others being investigated, IV
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describe the antimetabolites.
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flucytosine is only one, fungi have enzyme that convert it to FUA that competes with uracil for RNA synth, good bioavailabilty, used usually with other agents like amphotericin B, good for yeasts
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describe the allylamines.
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inhibits conversion of squaline to lanosterol and thus ergosterol biosynth. Terbinafine is for systemic use while naftifine is for topical use
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describe griseovulvin.
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oral agents for dermatophytes, second line
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what are typical stains for fungi IDing? how can microscopy of fungi be enhanced?
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gram, giemsa, and calcofluor. using KOH periodic acid Schiff stains.
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what kind of agar is used for growth of fungi and inhibition of bac growth?
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Sabouraud's dextrose agar
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size, shape, and number of what can help ID fungi?
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spores AKA conidia
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describe mycelial cell growth.
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coenocytic: cytoplasms connected, some have septae between them but there are holes in the septae so they are still coenocytic
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what are the two types of spores?
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asexual spores (anamorph) or spores resulting from reproduction AKA sexual spores (telomorph)
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describe the classification of fungi by diseases caused.
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superficial (outer skin and hair), cutaneous and subcutaneous (keratinized layer in cutaneous and deeper for SQ), endemic (systemic involving lung and subsequent spread to other parts of body), and opportunistic
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what drug combos are good for candidiasis, cryptococcus, aspergillosis?
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AMB + FCZ, amb + fc. AMB + FC, amb + fcz, fc + fcz. amb + fc, amb + azoles, amb + echinocandins, triazoles + echinocandins.
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clincial presentation of pityriaisis versicolor? diagnosis? treatment?
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normal flora, rash on upper torso or abdomen, microscope diagnosis, yeast and hyphae, topical azoles
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clinical presentation of tinea nigra? treatment?
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produces melanin rash, found as yeast and hyphae, topical therapy
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describe black piedra infections.
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nodules in hair, from poor hygeine, washing
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describe white piedra...?
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pasty cream colored growth in hair shafts, microscopic exam shows presence of hyphal cells
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the cutaneous mycoses cause what?
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tenia pedis, tenia capitis, tinea manus (hands), tinea unguium (nails), tinea corporis (body) or ring worm
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what type of fungi cause cutaneous mycoses and what are the three generea?
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dermatophytes: microsporum, trichophyton, epidemophyton... MET
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morphology of the cutaneous mycoses generas?
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epidermophyton has macroconidia with clusters and smooth wall. microsporium has large and thick macroconidia. trichophyton has rare smooth thin walled macroconidia and some microconidia that are tear or sphere shaped
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where do these infections occur: favic, ectothrix, and endothrix?
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in hair root, on hair shaft, in hair shaft
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3 epidemiologies of cutaneous mycoses?
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geophilic, zoophilic, and arthropophilic (chronic and noninflammatory but hard to kill).
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common clinical presentations of cutaneous mycoses?
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ringworm, alopecia, onychomycosis (nails)
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lab diagnosis and treatment for cutaneous mycoses?
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alkali treatment and microscopy then culture to ID the agent. skin infections with topical azoles, hair and nail treat orally with INTRACONAZOLE or TERBINAFINE or griseovulvin
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general epidemiology of SQ mycoses?
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rare in US and are from heterogeneous orgs in the soil
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what type of SQ mycosis is characterized by nodular and ulcerative lesions developing along the lymphatic glands that drain the primary site. can remain local and walled off as well.
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lymphocutaneous sporotrichosis
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describe the causative agent of lymphocutaneous sporotrichosis as well as its morphology and basic bio props.
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sporothrix schenckii, thermally dimorphic, mycelial colonies grow fast, narrow, septate hyphae with oval conidia, yeasts maybe cigar shaped
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epidemiology of lymphocutaneous sporotrichosis?
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warm climes, forest walk, mining, gardening
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lab diagnosis of lymphocutaneous sporotrichosis?
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culture is definitive, pleomorphic budding yeast in tissue, asteroid bodies may be in tissue
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treatment of lymphocutaneous sporotrichosis?
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classic is KI in saturated solution, current treatment is itraconazole
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describe all the aspects of chromoblastomycosis.
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denatiaceous fungi, seen in tropics and walkin in forest w/o shoes. warty, cauliflower growths that can become skin cancer. resistant to treatment and can be pruritic. diverse forms on culturing but all form muriform cells that are brown in tissue (copper colored spherical cells in tissue), treat with itraconazole and terbinafine but usually ineffective, heat and cryotherapy,
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what SQ fungal infection is characterized by chronic, granulomatous, infection and observation of granules or grains in aggregates. Amputation often indicated.
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eumycotic mycetoma
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zygomycosis and phaehyphomycosis are what type of fungal infections?
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SQ
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what are some basic facts about systemic mycoses.
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geographically restricted, inherently virulent and can cause disease in healthy individual, thermally dimorphic, host's immune status determines the severity of the disease
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epidemiology of histopasmosis?
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in soil with hign nitrogen contaminated with bird/bat crap. seen in midwestern US esp in Ohio and MS river valleys, common infection.
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what are the clinical presentation and pathogenesis of histoplasmosis?
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enters through the lung, phagocytosed by macs (unique in fungi), yeast replicate intracellularly, immunocompetent can contain infection, most asymptomatic. some get acute pneumonia, rare disseminated disease that is life threatening, seen in AIDS. Thermal dimorphism, needs to be yeast to cause disease, keeps pH of phagosomes high, iron and calcium uptake facilitated, cell wall grows in mac and leads to release
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lab techniques to diagnose histoplasmosis?
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serology, histo exam of infected tissue to see budding intracellular yeasts, culture blood, marrow, sputum, morphology is thin mold with branching septae that produce microconidia and tuberculate macroconidia.
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treatment for histoplasmosis?
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amphotericin B followed by itraconazole
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epidemiology of blastomycosis?
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North American Ohio and MS valleys and parts of Africa, natural disease of dogs and horses, soil, common
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clinical presentation and pathogenesis of blastomycosis?
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inhaled but primary lung infection is often asymptomatic, mild flu like, progressive pulmonary disease, systemic disease, classic form is chronic cutaneous involvement, uncommon in AIDS but very aggressive. Thermal dimorphism, yeast cells shed WI-1 glycoprotein to stimulate TH2 response
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diagnosis and morphologies of blastomycosis?
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microscopic exam for yeasts and culture from abscess fluid, sputum... Large extracellular broad base budding yeasts. septate hyphae with pyriform microconidia
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treatment of blastomycosis?
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amphotericin B, itraconazole for mild forms.
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epidemiology of coccidiodes?
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north, south, and central america. san joaquin valley: desert of Cali, Arizona and Texas, usually in soil
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clinical manifestations and pathogenesis of coccidiodomycosis?
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very virulent, self limited, mild fever to severe resp disease, small # of pts get progressive pulmonary or disseminated disease involving meninges or skin, thermal dimorphism, hydrophobic protein prevents phagocytosis, Th2 response, urease to help intracellular survival, extracellular proteinases, molecular mimicry
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how do you diagnose coccidioidomycosis? morpho?
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serology, culture sputum or tissue samples, microscopic ID from sample, CF test, agar diffusion... morph:filamentous mold that fragments to form infectious arthroconidia (spores). parasitic form is multinucleated sphrule that bursts open to release infectious endospores.
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treatment for coccidioidomycosis?
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amphotericin B followed by azole, extrapulmonary is oral azole only, meningeal coccio: fluconazole - amph B only if azole fails
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morphology and epidemiology of paracoccidioides?
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south america and latin america, dimorphic, mold with small microconidia and chlamydospores, yeast is large with multiple budding cells.
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morphology of cryptococcus?
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not dimorphic, budding yeast with acid mucopolysaccharide capsule that prevents phagocytosis
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epidemiology of cryptococcus?
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worldwide, excreta of pigeons association, but does not infect them, associated with AIDS, most common cause of fungal meningitis
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clinical manifestations and pathology of cryptococcus..?
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asymptomatic pulmonary infection to symptomatic pneumonia to systemic disease fatal if left untreated, grows at 37 C, polysaccharide capsule, melanin, and has a mating type...
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diagnosis and treatment of cryptococcus?
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antigen detection in CSF, india ink detection of encapsulated yeast in CSF, culture of specimens from blood or CSF. amphotericin B plus 5 fluorocytosine
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mnemonic for blastomycosis?
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Blastomycosis is big, broad based budding
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