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68 Cards in this Set
- Front
- Back
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What is the target of echinocandins?
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b-glucan synthesis
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What class of drug interferes with b-glucan synthesis?
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Echinocandins
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What is the target of Nikkomycins?
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Chitin synthesis
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What class of drug interferes with Chitin synthesis?
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Nikkomycin
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What is the target of allylamines?
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Ergosterol Synthesis
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What is the target of anti-fungal azoles?
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Ergosterol synthesis
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What classes of drugs interfere with ergosterol synthesis?
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Allylamines
Anti-fungal Azoles |
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Arthroconidia, chlamydospores, sporangiospores are all examples of what type of spores?
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Asexual spores (conidia)
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Zygospores, basidiospores, and ascospores are all examples of what type of spores?
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Sexual spores
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Which are asexual spores?
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Conidia
-arthroconidia -chlamydospores -sporangiospores |
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Which are sexual spores?
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Zygospores
Basidiospores Ascospores |
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How are fungi classified?
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Reproductive structures: asexual vs sexual
Tissue involvement: superficial, cutaneous, mucocutaneous, systemic +/- dissemination Host response: primary fungi vs opportunistic fungi |
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What fungal compound activates complement?
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Mannose to Mannose-binding lectin
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What conditions lead to immunocompromise?
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malnutrition
low birth weight neonates antibiotic treatment immunosuppressive drugs (cyclosporin A for transplant patients or autoimmune patients) AIDS |
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Which cellular response mediates clearance of fungi?
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Th1 response
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Why is direct detection of fungi difficult?
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Opportunistic infections are difficult to interpret
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Why is culture of fungi difficult?
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Fungi may take several weeks to culture
Opportunistic infections are difficult to interpret |
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Why is detection of antibodies to fungus difficult?
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Antibodies in primary infections may cross react.
Antibodies to opportunistic infections may not be produced in the immunocompromised. Antibodies may not be produced against normal body flora. |
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What mediates the skin test detection for fungi? Why is the skin test difficult for detecting fungus?
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Intradermally injected fungal antigens cause cell-mediated immunity reactions in those exposed to the antigens.
Primary infections may have cellular reactions which cross react Immunocompromised patients may not mount a cellular response. |
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How is Cryptococcus neoformans often detected?
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The latex agglutination test detects antigens in the CSF.
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Why is detection of fungi using DNA probes difficult?
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DNA probes are not available everywhere.
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What is the target of Flucytosine?
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5-flucytosine inhibits DNA/RNA synthesis in fungi
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What is the target of Griseofulvin?
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Griseofulvin prevents spindle formation at mitosis.
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What is the infectious agent of Coccidioides immitis?
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Arthrospores
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Explain the life cycle of Coccidioides immitis.
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Coccidioides imitis mold form arthrospores are inhaled and turn into yeast form spherules containing endospores. The spherule matures and ruptures, releasing thousands of endospores which can each turn into another spherule.
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How does Coccidioides immitis resist phagocytosis?
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The spherules are too large for phagocytosis
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What are the clinical forms of Coccidioides immitis infection?
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Pulmonary coccidioidomycosis
Disseminated coccidioidomycosis -Meningitis -Bone and Joint infection -GU infection -Cutaneous infection -Opthalmic infection |
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Which fungus causes meningitis?
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Disseminated Coccidioides imites
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Explain the dimorphism of Candida albicans?
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Candida albicans grows as a budding yeast or with pseudohyphae.
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How does the dimorphism of Candida albicans help it evade the destruction by the immune system?
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The budding yeast form of Candida albicans stimulates an effective Th1 response, while the germ tube and pseudohyphae form of Candida albicans stimulates an ineffective Th2 response.
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What sort of fungal pathogen is Coccidioides imites? Who does it infect?
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Primary fungal pathogen
Infects everyone |
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What sort of fungal pathogen is Candida albicans? Who does it infect?
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Opportunistic endogenous fungal pathogen
Infects immunosuppressed or those with imbalances in the normal flora. |
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What sort of fungal pathogen is Aspergillus spp.? Who does it infect?
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Opportunistic exogenous fungal pathogen
Infects immunosuppressed regardless of normal flora state. |
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What is the mode of transmission of Candida albicans? How can it be introduced?
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Candida albicans is endogenous and can exhibit mucosal overgrowth or be introduced with a catheter and disseminate hematogenously.
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What is the purpose of glycoproteins on Candida albicans?
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The glycoproteins on Candida albicans allow adherence to host cells and evasion of the immune system.
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What sorts of infections does Candida albicans cause?
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Oral/vaginal thrush
Vaginitis Chronic mucocutaenous candidiasis Skin and soft tissue candidiasis Hematogenous candidiasis |
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How is candidiasis diagnosed?
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GMS stain shows germ tube production or bud formation when sample is grown on corn meal agar.
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What is the most common invasive mold infection?
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Aspergillus spp.
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How does aspergillus grow in the body and in the environment?
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Aspergillus is monomorphic and grows as mold with v-shaped, branched hyphae with conidiophores with terminal conidia.
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How does aspergillus evade the immune system using morphological and protein methods?
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Aspergillus conidia stimulate an effective Th1 response while Aspergillus hyphae stimulate an ineffective Th2 response. Aspergillus gliotoxin inhibits T cell response and proliferation and macrophage phagocytosis
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What factors contribute to aspergillus spp. virulence?
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elastase
phospholipase proteases catalase gliotoxin |
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What does aspergillus gliotoxin do?
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Gliotoxin inhibits macrophage phagocytosis and T-cell activation and proliferation
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What infections does aspergillus cause?
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ABPA - asthma symptoms
Disseminated Aspergillosis - aspergillomas |
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How is ABPA diagnosed?
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High anti-aspergillus antigen IgE titers and eosinophilia
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How is Aspergillus spp. diagnosed?
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Galactomannon in the serum
Characteristic growth on media |
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What is parasite infection? What are the most common modes of infection?
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When the parasite is present in the internal organs or tissues. The most common modes of infection are oral ingestion or direct cutaneous penetration.
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What is parasite infestation?
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Infestation occurs when the parasites are present on the hair, skin, and clothing.
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What is a definitive host?
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A definitive host is one in which parasites undergo sexual replication.
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What is an intermediate host?
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An intermediate host is one in which parasites undergo a larval stage of development, but not sexual reproduction.
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What is a paratenic host?
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A paratenic host is one in which parasites pass through without undergoing a larval stage of development or sexual reproduction.
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What is the incubation period?
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The incubation period is the time between the acquisition of infection and the appearance of clinical symptoms.
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What is the prepatent period?
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The prepatent period is the time between the acquisition of infection and the shedding of eggs, larvae, or microfilia.
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What is the patent period?
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The patent period is the time during which the diagnostic stages are shed.
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Which organisms are intestinal protozoa?
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Entamoeba histolytica
Giardia lamblia Cryptosporidium spp. |
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Which organisms are urogenital protozoa?
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Trichomonas vaginalis
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Which organisms are free-living amoebas?
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Naegleria fowleri
Acanthamoeba spp. |
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Which organisms are intestinal coccidium?
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Toxoplasma gondii
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Which organisms are extracellular protozoa?
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Pneumocystis jiroveci
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Which organisms are hemoflagellates?
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Trypanosoma spp
Leishmania spp |
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Which organisms are malaria parasites?
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Plasmodium spp.
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What are frequently used methods for the diagnosis of parisitic infections?
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Diagnosis of parasitic infection is based on symptoms, detailed travel history, food intake history, transfusion history, and socioeconomic history.
Methods of diagnosis include: Macroscopic exam Microscopic exam Wet mount Permanent stain Stool concentrates Serologic exam Antibody and antigen responses Nucleic acid hybridization Culture Animal inoculation Xenodiagnosis |
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Why is treatment of parasitic disease difficult?
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Ask Jean?
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Which organism is known as beef tapeworm? How is it diagnosed?
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Taenia saginata segments are found in the feces.
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What disease results from schistosoma infection? What causes the disease?
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Schistosomiasis is caused by the host response to the schistosoma eggs. A granulomatous reaction occurs which can eventually lead to hyper-responsiveness and clay pipe-stem fibrosis.
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What organism and disease causes clay pipe-stem fibrosis?
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Schistosoma causes schistosomiasis which is a granulomatous reaction in the liver against the schistosoma eggs. Hyper-responsiveness can lead to clay pipe-stem fibrosis.
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What is the appropriate drug for treating schistosomiasis?
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Praziquantel
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Does praziquantel affect lesions caused by eggs deposited in tissues?
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No. Praziquantel terminates oviposition
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How and where does infection by schistosoma occur?
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In fresh water, where cercariae penetrate the skin of humans
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