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65 Cards in this Set
- Front
- Back
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What are the natural reservoirs of Fusarium?
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plants, soil
can't bring plants in hospital rooms b/c fusarium and aspergillus |
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How does one obtain a Fusarium infection?
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traumatic inoculation (usually)
disseminated infections usually result of immune system suppression |
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What are the infectious preferences of Fusarium?
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cutaneous infection
spreads to heart and bones if it gets into your blood contact lenses/corneal infections |
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Why are macrophages not so useful for fighting fungal infections?
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NAIVE macrophages ingest but do not immediately kill fungi
fungi continue to grow --> hyphae or buds lyse macrophage |
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After the skin, what is the primary immune defense against fungal infections?
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Neutrophils
--> neutropenia predisposes to mycoses |
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What do polyene drugs target?
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Fungal cell membrane function
bind ergosterol and make pore in membrane |
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What are some problems with polyene drugs?
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low solubility --> mostly topical use or IV, not good for systemics
cause kidney and liver problems |
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What solution has been developed for low AmB solubility?
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create liposomes with AmB embedded in membrane
macrophages engulf --> become saturated with AmB --> when they eat fungi AmB works inside macrophage! |
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What are some examples of polyene drugs?
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Nystatin
Amphotericin B (last resort b/c not much resistance) |
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What does 5-Flu-Cytosine target?
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DNA/RNA synthesis
only fungi have enzyme to convert 5-Flu-C to 5-Flu-Uracil and incorporate it into DNA. |
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What are some problems with 5-Flu-Cytosine?
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easy to develop resistance
cannot be used alone, must be combined with another drug. |
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What do azole drugs target?
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Ergosterol biosynthesis at ERG11 gene
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What are the two classes of azole drugs and what types of mycoses are they used for?
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imidazoles (OTC, topical application)
triazoles (Rx only, for systemic infections) |
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What are some examples of azole drugs?
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OTC: ketoconazole, clotrimazole, miconazole
Rx: FLUCONAZOLE!, voriconazole, itraconazole New: Posaconazole |
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What are some other examples of ergosterol biosynthesis inhibitors?
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ERG1: terbinafine (Lamisil), tolnaftate (Tinactin)
ERG24 and ERG2: aorolfine, fempropimorph |
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What do echinocandins target?
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Inhibit cell wall synthesis --> fungi more susceptible to phagocytosis
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What are some problems with echinocandins?
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low solubility --> IV only
new so we don't know long term effects |
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What drug is being used to treat mycoses in African AIDS patients?
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Fluconazole (Pfizer: Diflucan)
Leaning toward HAART now |
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What is HAART?
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Highly Active Antiretroviral Therapy
Restore immune system function to AIDS patients (hopefully) |
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What are some problems with azoles?
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don't kill, just inhibit growth
fungi may develop resistance |
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Which groups of fungi are hardest to treat with existing antifungal medication?
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Zygomycetes
Fusarium spp. Scedosporium spp. |
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What species are resistant to azoles?
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some Candida, Cryptococcus, Aspergillus species found in AIDS, Bone Marrow Transplant, etc, patients
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What is the difference between primary and secondary resistance?
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primary = naturally resistant, always been that way
secondary = strain gains resistance via mutation, lateral gene transfer, etc. |
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Which Candida species are most likely to be drug resistant?
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C. lusitaniae, C. krusei (AmB), C. glabrata (Azoles)
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Which Cryptococcus species is considered a "true pathogen" and why?
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C. gatii because it attacks even non-immunocompromised patients.
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MIC = ?
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Minimum Inhibitory Concentration
conc. of antifungal drug required to inhibit growth |
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Which black mold species has been implicated for "sick building syndrome," etc.?
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Stachybotrys chartarum, S. atra
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What humidity level is required for production of mycotoxins by Stachybotrys species?
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~95%
a swamp, basically. so no mycotoxins in your house, unless you live in a swamp. |
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What are the goals of the California Toxic Mold Protection Act of 2001?
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-establish research priorities
-provide sampling/investigation/remediation guidelines -disclosure of mold in properties (real estate) |
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Describe the pseudohyphae of Candida albicans.
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single cell (no septation)
elongated, bullet-shaped, un-separated buds. sausage links |
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Which strains of Candida form Chlamydospores? What is their purpose?
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C. albicans
occur at end of hyphae; purpose unknown |
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Which Candida species form septate hyphae?
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only C. albicans and dubliniensis
the rest form aseptate hyphae |
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How does Candida appear in tissue?
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EVERYTHING
budding yeasts + hyphae + pseudohyphae |
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Where does Candida like to grow?
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plastics: dentures, catheters, implanted heart valves
everywhere in environment and world everywhere in all humans (commensal) |
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What factors predispose one to vaginal yeast infections?
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-tight skanky clothing
-hormone imbalances (pregnancy, oral contraceptives) -anemia -taking antibiotics that kill lactobacilli |
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What are the risk factors for oral and esophageal Candidiasis?
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-immune suppression (diabetes, AIDS)
-poor oral hygiene! -infants: immature immune system -high sucrose diet -antibiotics |
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What causes the white "bloom" on your tongue when you take antibiotics?
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bloom of candida
all your oral bacteria are dead so candida party hardy |
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What are the three types of oral candidiasis?
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pseudomembranous
erythematous angular chelitis |
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What are the symptoms of pseudomembranous candidiasis?
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overgrowth of white yeast patches in mouth
pain, loss of appetite |
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What are the symptoms of erythematous candidiasis?
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appetite loss, pain, inflammation in roof of mouth due to small number of yeast cells in tissue.
subtle; most often Dx by dentists |
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What are the symptoms of angular chelitis?
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crusty patches, lesions at corners of mouth due to infection by candida spp
pain, loss of appetite |
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What are the symptoms of Esophageal candidiasis?
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ulcerations and white patches of yeast growth on esophagus lining
may spread to stomach, GI tract, respiratory tract, urinary tract |
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What is a nosocomial infection?
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an infection obtained while one is staying in a hospital
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What predisposes you to systemic candidiasis (blood infection)?
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-immune suppression: neutropenia, chemotherapy
-catheters -surgery -artificial heart valves -burns |
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Where does candida often spread in systemic infections?
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-skin (esp heroin addicts)
-kidneys because candida in blood lodges in kidneys |
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What is Chronic Mucocutaneous Candidiasis?
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immune dysfunction
candida grows on all mucosal surfaces --> crusting, hyperkeratosis, chronic skin infections treat with topical antifungal drugs. |
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Which Candida species form germ tubes?
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C. albicans
C. dubliniensis *in vitro only diagnostic test for these species* |
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What genus is responsible for most mucormycoses?
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Rhizopus: 60% of all cases
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What is the pathology of mucormycosis?
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twisting hyphae grow rapidly in tissue
invade blood vessels --> block blood flow --> necrosis from lack of blood |
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What are the most frequent etiologic agents of mucormycoses?
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Rhizopus microsporus (var. rhisopodformis)
Cunninghamella betholletiae Saksenaea vasiformis |
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What are natural reservoirs of mucoraceae?
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decaying matter containing carbohydrates
soil, compost, animal poo common lab contaminant. |
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Why are nosocomial mucormycoses on the rise?
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We've got aspergillosis and candidiasis under control --> mucoraceae have no competition
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Mucormycoses may indicate underlying disease. Examples?
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-diabetic ketoacidosis
-steroid use -leukopenia -lymphoma -neutropenia |
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How does one usually obtain mucormycoses?
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traumatic inoculation (immune compromised)
takes a huge dose to infect healthy immune competent person. |
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What is the most damaging form of mucormycosis?
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Mucormycotic sinusitis because it spreads to your BRAIN
puts you in a coma, kills you in 4 weeks |
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What are symptoms of pulmonary mucormycosis?
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fever
rapidly progressing lung invasion lesions in trachea and bronchial tubes lung necrosis death in 2-3 weeks |
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What is the taxonomic classification of Pneumocystis carinii?
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Archiascomycete
previously thought to be a protozoan b/c similar drug susceptibility and has double membrane no ergosterols |
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Why is Pneumocystis carinii so difficult to study?
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unable to culture in vitro.
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What are the infectious preferences of Pneumocystis carinii?
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-only mammalian lungs
-very picky and species specific -opportunistic infection of severely immune compromised only |
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What are the natural reservoirs of Pneumocistis carinii?
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all mammalian lungs
we've all got it in our lungs commensally |
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What are trophozoites?
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Active stage Pneumocystis carinii cells
amoeba-like with filopodia for adhesion to host lungs |
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What are sporozoites?
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intracystic bodies of P. carinii; develop into trophozoites upon cyst maturation.
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What are the symptoms of Pneumocystis carinii Pneumonia (PCP)?
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pneumonia, inflammation, fever
death by asphyxia foamy excretion from lungs containing P. carinii cells |
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What is the most common AIDS-defining opportunistic infection?
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PCP
Pneumocystis Carinii Pneumonia |
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Which Aspergillus species is known to be drug-resistant?
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A. terreus
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