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Which type of Aspergillus species is commonly associated with allergic bronchopulmonary aspergillosis (ABPA)?
What temperature range does Aspergillus species thrive in?
What is a common mode of transmission for Aspergillus species in a clinical setting?
Which of the following conditions is NOT typically caused by Aspergillus species?
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In what type of infections can Aspergillus species invade the body?
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Which serotypes of the ion are considered highly virulent?
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What is the most likely source of saprophytic varieties of this ion?
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Which infection does Candida gattii most commonly cause?
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What trait is associated with the urease positive species of this ion?
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Which type of fluid is most indicative of a Cryptococcus infection?
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What fungal treatment is typically effective for disseminated infections in AIDS patients?
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Which condition is likely to result from untreated pulmonary infection by this ion?
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Which type of disease is associated with Candida neoformans?
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What do most infections (90%) relate to in patients with neutropenia?
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Which condition is primarily associated with hemoptysis in infections?
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What does the presence of septate hyphae indicate in a patient's lungs?
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In which population are pulmonary fungi particularly dangerous?
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What kind of lesions are often associated with fungal infections in the lungs?
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What is produced in large amounts by certain molds, posing a risk to the lungs?
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Which of the following is a prerequisite test for lungs suspected of infection?
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What condition can result from the invasion of hyphae in lung blood vessels?
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What role do environmental molds play in lung health?
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What is the main impact of fungal infections on patients with compromised immune systems?
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Which factor increases susceptibility to mucormycosis?
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What is the primary characteristic of dimorphic fungi?
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What type of reactions can fungi cause in humans besides infection?
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Which of the following fungi is classified under the Mucormycetes class?
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Which types of spores are recognized in fungal reproduction?
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What is a common symptom of rhinocerebral mucormycosis?
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How do antifungal agents generally work?
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Which group of fungi is NOT typically pathogenic?
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What type of test can be used to identify fungal infections quickly?
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Which of the following conditions is most likely to predispose someone to fungal infections?
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What is the major class of fungi that includes species like Aspergillus?
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What role does free iron play in relation to fungal growth?
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Which fungus is known for causing notable opportunistic infections in immunocompromised patients?
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What is typically the main symptom of intoxication from fungi?
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What is a mode of transmission for Coccidioidomycosis?
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Which of the following features is associated with Coccidioidomycosis?
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What is a significant clinical manifestation of Coccidioidomycosis?
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Which method is included in the laboratory diagnosis of Coccidioidomycosis?
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How do arthrospores develop in Coccidioidomycosis?
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What type of organism is primarily responsible for Coccidioidomycosis?
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What role do endospores play in Coccidioidomycosis?
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What kind of infection does disseminated Coccidioidomycosis refer to?
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What is a potential consequence of inhaling Coccidioides spores?
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What does 'Septation of arthroconidia' refer to?
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Coccidioidomycosis primarily affects which population group more severely?
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Which of the following represents a key feature of the treatment for Coccidioidomycosis?
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What is crucial for preventing Coccidioidomycosis infection?
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Which of the following statements is true regarding the morphology of Coccidioidomycosis?
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Study Notes
Cryptococcus
- The Cryptococcus capsular serotypes A, D, and AD are highly virulent.
- Cryptococcus is found saprophytically in soil, especially pigeon droppings.
- Cryptococcus produces lung nodules in compromised individuals.
- Cryptococcus neoformans usually manifests within 9 weeks after infection.
- Cryptococcus neoformans causes consolidation within the lungs after infection.
- Subcutaneous nodules can occur with oral fluconazole or itraconazole treatment.
- Disseminated disease occurs with itraconazole or fluconazole treatment.
- Disseminated Cryptococcus neoformans infections are difficult to differentiate from Candida infections.
- Treatment for Cryptococcus neoformans is with fluconazole.
- Fluconazole is effective for long-term suppression of cryptococcosis in AIDS patients.
Candida
- Candida albicans, Candida glabrata, and Candida tropicalis are urease positive.
- Candida can be isolated from a variety of samples, including exudates, spinal fluid, tissue, sputum, blood, and urine.
Aspergillosis
- Aspergillus species are found in soil, air, and decaying matter.
- Aspergillus fumigatus is the most common cause of aspergillosis.
- Aspergillus fumigatus can establish disease after ingestion of aflatoxins.
- Aspergillus fumigatus can be identified in respiratory samples, skin scrapings, and tissue.
- Aspergillus flavus, Aspergillus fumigatus, Aspergillus clavatus, Aspergillus niger, Aspergillus terreus, Aspergillus restrictus, and Aspergillus amstelodamii are all common species.
- Infections can occur in wounds, burns, external ear, cornea, or paranasal sinuses.
- Aspergillus can be isolated from sputum, respiratory specimens, soil, and skin scrapings.
- Allergic bronchopulmonary aspergillosis (ABPA) is an allergy to Aspergillus spp.
- ABPA is a common complication of asthma.
- Invasive aspergillosis is a serious infection that can occur in immunocompromised patients.
- Colonization occurs in the lungs and other extrapulmonary organs
- Aspergillus can cause cutaneous, mucocutaneous, visceral, cerebromeningeal, and ocular infections.
General Properties of Fungi & Laboratory Identification Methods
- Fungi are eukaryotic, heterotrophic organisms that lack chlorophyll
- They obtain nutrients by absorbing organic compounds produced from other organisms
- Fungi are ubiquitous and grow in a variety of environments such as soil, air, water, and plants
- They can be unicellular (yeasts) or multicellular (molds)
- Fungi reproduce by spores
- They are useful for creating pharmaceuticals and food products
- They are also responsible for causing diseases in humans, plants, and animals
- Some fungi can exist in yeast or mold states depending on the environment
- Laboratory methods for identifying fungi can be used to determine morphology, growth characteristics, and biochemical properties
- Microscopic examination can be used to identify fungal structures such as hyphae, conidia, and spores
- Culture is a widely used technique for identifying fungi and identifying various fungal species
- Cultures require a medium enriched with nutrients, vitamins, and other organic compounds
- Isolation is used to grow a single fungal species
### Yeast
- They are unicellular fungi that reproduce asexually by budding
- The budding process leads to daughter cells which detach from the parent cell or remain attached until new buddings can occur
- The daughter cells of budding yeast are genetically identical copies of the parent cell
Mold
- They are multicellular fungi that reproduce both sexually and asexually
- They produce spores for dispersal
- Molds are typically characterized by hyphae, filamentous structures that branch extensively
Dimorphic Fungi
- Dimorphic fungi can grow in two forms, depending on the environmental conditions
- They can grow in a saprophytic form which is non-disease causing, as a mold, that is typically found in the environment
- They also exist in pathogenic forms which can cause disease in humans in the yeast form which are typically found in humans
- They are clinically significant as they can cause a variety of infectious diseases
### Fungal Reproduction
- Asexual reproduction involves the production of spores by a single parent cell in the fungal state
- Sexual reproduction involves the fusion of two haploid nuclei from distinct parent fungal states to form a diploid zygote that develops into a new organism
- Conidia are asexual spores produced by molds and some yeasts
- They are non-motile spores that are dispersed by air currents or through water
- Sporangiospores are asexual spores produced by some molds
- They are enclosed within a sac-like structure known as a sporangium
- Classification of true fungi based on representation
- This classification system helps categorize the fungi with related structures for reproduction
- Major Classes of Fungi
- Mucormycetes: commonly found in the environment, commonly associated with infections in individuals with compromised immune systems
- Rhizopus, Mucor, Basidiobolus: examples of species within this class
- Basidiomycetes: a large and diverse group of fungi including important edible mushrooms
- Cryptococcus, Malasezzia, Trichosporon: examples of species within this class
- Pneumocystidomycetes: a class of fungi that includes the opportunistic pathogen Pneumocystis, which causes pneumonia
- Pneumocystis jirovecii: a prominent species within this class
- Saccharomycetes: a class of fungi that includes several important yeast species, including Saccharomyces cerevisiae, used for baking and brewing.
- Candida, Saccharomyces: examples of species within this class
- Eurotiomycetes: a large and diverse class of fungi that includes several important genera like Eurotium
- Dermatophytes, Blastomyces, Histoplasma, Aspergillus, Fusarium: examples of species within this class
### Fungal Identification
- Direct microscopic examination involves the use of a light microscope to examine fungal samples and identify characteristic structures like hyphae, conidia, and spores
- Culture involves growing fungal samples in a suitable medium
- Initial observation in studying fungal isolates allows for identification of colonies
- Germ tube test is a quick and simple test used specifically for the identification of Candida albicans
- Antigen-antibody tests are used to detect specific fungal antigens present in bodily fluids
- Biochemical tests help determine fungal metabolic properties like sugar metabolism or fermentation
- Detection of DNA or RNA are molecular methods used to identify fungal species by analyzing nucleotide sequences
### Antifungal Mechanisms
- Antifungal medications target a specific pathway, structure, or component of the fungal cell, preventing the fungus from growing and multiplying
- Targeting the cell membrane
- Some antifungal medications, like amphotericin B, interfere with the ergosterol synthesis in the fungal cell membrane
- This disrupts the fungal cell membrane leading to cell death and inhibiting growth
- Targeting DNA synthesis
- Fluconazole is an antifungal drug that inhibits the synthesis of DNA blocking the essential steps in replication
- Targeting cell wall formation
- Echinocandins are a group of antifungal drugs that block synthesis of 1,3-beta-D-glucan, a component of the fungal cell wall
- This weakens the cell wall and ultimately results in cell death
- Targeting cell division
- Griseofulvin is an antifungal medication that inhibits the formation of microtubules playing a role in cell division and growth
### Superficial Mycoses
- Superficial mycoses are fungal infections that affect the outer layers of the skin, hair, and nails
- The most common superficial mycoses are **tinea ** or ringworm
- Tinea versicolor is a superficial fungal infection caused by the yeast Malassezia globosa
- Tinea nigra is a superficial fungal infection caused by the fungus Hortaea werneckii
- Black Piedra is a superficial fungal infection that affects the hair, characterized by dark, hard, and round nodules formed around the hair shaft
- White Piedra is a superficial fungal infection affecting the hair, characterized by pale-colored, soft, and round nodules that form around the hair shafts
### Cutaneous & Subcutaneous Mycoses
- Cutaneous mycoses are fungal infections that affect the skin, hair, and nails
- Subcutaneous mycoses are fungal infections that affect the deeper layers of the skin and subcutaneous tissue
- Dermatophytes are fungi that can infect the skin, hair, and nails
- They are classified into geophilic, zoophilic, and anthropophilic categories based on their ecological niche and the source of infection
- Dermatomycosis is a group of diseases caused by dermatophytes
- Candidiasis is a fungal infection caused by the yeast Candida albicans
- Cutaneous mycoses are associated with various symptoms including the presence of patches, lesions, and scaling on the skin
- The transmission of dermatophytes occurs through direct contact with infected individuals, animals, or contaminated objects
- Cutaneous mycoses are identified by examining the skin lesions under a microscope for fungal elements like hyphae and spores
- Dermatophyte culture is used to isolate and identify the fungal species responsible for the infection
- Antifungals for dermatomycosis are available for oral or topical use
- Cryptococcosis is a systemic fungal infection caused by Cryptococcus neoformans
- Cryptococcus neoformans is a yeast-like fungus found in bird droppings and decaying wood
- Cryptococcosis is an opportunistic infection that primarily affects individuals with weakened immune systems
- Cryptococcosis is diagnosed through microscopic examination of cerebrospinal fluid or blood cultures, and serological tests
- Cryptococcosis can cause a variety of symptoms, including pneumonia, meningitis, and skin infections
- The treatment of cryptococcosis involves antifungals such as fluconazole
### Subcutaneous Mycoses
- Sporotrichosis is a subcutaneous fungal infection caused by Sporothrix schenckii
- Sporothrix schenckii is a dimorphic fungus found in soil, decaying wood, and the spines of plants
- Sporotrichosis is usually contracted through skin trauma, like a puncture wound, that comes into contact with contaminated material
- Sporotrichosis is diagnosed through culture and microscopic examination
- Treatment of sporotrichosis involves antifungal drugs like itraconazole or potassium iodide
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