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28 Cards in this Set
- Front
- Back
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What are the characteristics of fungi?
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1. heterotrophs - feed on organic materail.
2. fungi will "digest" then "ingest" so they secrete enzymes and then are able to take it in. |
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What is the nature of fungi? type of food that is fungi? Antibiotics?
What 'bad' things make up fungi? |
Nature: decay of organic material
food; mushrooms, soy sauce, cheses, tempeh bad: toxins plant diseases: wheat rust, oat smut, potato blight, ortten crops, etc. -disease of animals including people antibiotics: penicilin, cephalosporins.. All types of fungi |
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Describe fungal toxins and fungal allergens
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mushroom poisoing- most commonly due to ingestion of deathcap amanita phalloides
-other fungal toxins, generally acquired from contaminated grains have been described. Allergens: exposure to fingui triggers symptoms of asthma, rhinitis, sinusitis. -has role in 'sick building syndrome' |
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What domain does fungi belong to?
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belongs to domain Eukarya.
same domain as plants, animals, protista, and stramenopila. we're more closely related to fungi than we are to plants. |
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Differentiate between fungi and bacterai
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fungi: large size, eurkaryotic well defined membrane, mito, Golgi, ER, cells wall have chitin, glucans, mannan
bacteria - very different cell wall ocomposition |
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Fungi vs. people
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Both have similar nucleus and cytoplasms. but fungi have ergosterol in plasma membrane, but people have cholesterol in plasma membrane.
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What's the difference between cholesterol vs. ergosterol
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the difference is not very great, but just by one double bond in ergosterol. led to a long of fungal drugs that we have
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What are some major targets of antifungal drugs?
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ergosterol in plasma membrane
cell wall beta-glucans |
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Name some systemic antifungal drugs
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1. amphotericin B - most potent but has a lot of poor side effects. only administered through IV
2. azoles (fluconazole) - available orally and IV. less toxicity. fluconazole is most common one, especially helpful against most common fungal infection candida. 3. echinocandins- B glucan syntehsis inhibitor, available only via IV. |
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Describe the morphology of fungi?
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Can be yeasts, molds, or dimorphic = medically important.
Yeasts reporduce by budding, or fission. sometimes form elongated sausage like structures called pseudophyphae. Molds can have septate (has walls) or aseptate (no walls) hyphae fission - more in bacteria, NOT fungi. |
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How is fungi grown in the lab?
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-special media called Sabouraud medium
-clinician has to request fungal cultures when appropriate. fungi grow slower than bacteria so if you have mixed infection, bacterial will overgrow the fungi. So, you need to specifically request teh specimen. Sabouraud will inhibit growth of bacteria. |
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What are 3 classifications of human mycoses
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1. superficial
2. subcutaneous 3. systemic/deep |
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What is dermatophytes? what category?
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superficial.
-modls that invade keratinized tissue -zoophlic (animal to human), geophilic (soil to human), anthropophilic (human to human) - occurs at any skin site. feet (athlete's foot), groin, etc. - will see tinea corporis (ringworm) |
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Describe subcuteanous myocoses
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causes disease in subcutaenous tissue, but very uncommon.
examples: mycetoma (maduara foot) - can be seen in developing countries with those working in fields w/o shoes; sporotrichosis - get site of trauma and its spreads along lymphatics. |
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Systemic mycoses
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-includes candidiassi, which also causes superficial mycoses.
-can be divided into opportunistic and pathogenic. opportunitis: immunocompromised pathogen; affects anyone. |
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Candidiasis
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most important of fungal infections!
Agens: species of candida C. albicans but there are non- albicans species emerging (C. trpicalis, C. glabrata, C. parasilosis) morph: yesast, pseudohyphae, hyphae in tissue epidemiology: colonization is common, infection ensures when host defnses break down. most common of myocoses. |
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clincal freatuers of candidiasis. 2 entities
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1. mucocuteneous candidiases - occurs in thsoe with T cell mediated immunity defects; DM, those have spectrum antibiotics
2. disseminated candidiasis: those w/ neutropenia (low white cell count), IV catheters, surgery (esp GI) |
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What is thrush?
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Its oral candidiasis, a form of mucocutaneous candidiasis that is usualy first clinical manifestation of HIV infection.
-pseudomembranous - white plaques that can be scraped away -atrophic - smooth red patches -angular chelitis - erythema, cracks, fissures at corner of mouth -hyperplastic (candida leukoplakia) white plaques can't be scraped away) |
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Discuss denture stomatitis
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candida denture stomatitis.
-see erthyema and edema at portion of mouth that comes into caontact w/ dentures. - seen in up to 60% of denture weareres, usually in women. -occurs in ill fitting denstures. usually asymptomatic but some complaining. -wearers are predisposed since denture gets colonized with candida and loss of anticandida effects of saliva. thrush is also associated w/ xerostomia. - need to treat denture and the pt. lesions are erthematous but don't see pseudomembranes. |
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Disseminated candidiasis
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usually in GI tract or IV catheter portal of entry.
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Crytococcosis
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agent; crypto coccus neoformans and C. gattii.
-only medically important fungus w/ a capsule =opportunistic: affect those with impaired T cell immunity, esp those w/ AIDS -predilection to cause meningitis. -India ink used to stain it, but the stain is unable to penetrate into it. |
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Aspergillus fumigatus
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most common mold in environment.
-if pt is infected, it will grow into hyphae. can see mold with conidia (spores) in environment. generally have good host defenses against spore and hyphae form. Agent: species of aspergillosis. one end of spectrum is allergic manifestations. can cause end stage lung disease. Aspergilloma occurs in those who have preexisting cavities in the lung (smokers, etc.). aspergilloma takes up residence in cavities and lives w/o host recognizing it. can cause coughing up blood. -most feared end of spectrum is Invasive apergillosis. esp in immunocormporomised individuals. 60% mortality rate. Clinical: hemmorrhagic infarction (invades blood vessels, errodes it, clogs it and causes stroke) |
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Mucormycosis
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agent: variety of aspetate fungi
epi: ubqiutous in environment clinical: affects those with DM, ketoacidosis, neutropenia - rhinocerebral mucormycosis is rapidly progressive disease that needs aggressive debridement and antifungal therapy. Diabetics get rhinocerebral mucormycosis – fungus invades mucous membranes and spreads to sinuses, face, orbit, meninges and frontal lobe of brain. Often see black, necrotic lesions. First manifestation of disease often is lesions in the oral cavity |
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Pneumocystosis (PCP)
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agent: pneuocytsis jiroveci - formally classified as parasite
affects those with low CD4 t cell counts, esp those with HIV+ -most common life threatening infection in AIDS pts in US -usually causes pneumonia |
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Thermally dimorphic fungi
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-grow as molds in nature
-at 37degrees C phase conversion to yeast occurs in mammals -most are geographically restricted -oral ulcertions or granulomas are occasionally seen. |
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Coccidioidomycosis
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Agent - coccidioides immites and C. posadasii
-thermaly dimporhis fungus with unique life cycles -can be hyphae in soil. -in lungs or humans, can seen as mature spherule. contains endospores and makes a new spherules. each endospore makes a new spherule. -endemic in southwest US, Latin america -occurs in those immunocompromised, and more common in those with impaired CMI, esp AIDS. |
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Histoplasmosis
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Caused by Histoplasma capsulatum. Endemic in Central United States (Mississippi and Ohio River Valleys). Grow as hyphae in nature and yeasts in people. Intracellular parasite of macrophages. Similar to coccidioidomycosis, histoplasmosis is more common in those with impaired cell-mediated immunity, especially AIDS, but also causes disease in people with apparently normal immune systems. Several cases of histoplasmosis presenting as tongue lesions have been described.
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Paracoccidiodomycosis
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Caused by Paracoccidioides brasiliensis. Endemic in parts of Latin America. Up to one half of patients with paracoccidioidomycosis present with mucocutaneous lesions in or around the mouth. In endemic areas, most of these cases are first seen and diagnosed by dentists.
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