Fungal Pathogens and Morphology Quiz
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Questions and Answers

Which fungus is intrinsically resistant to Fluconazole?

  • Cryptococcus neoformans
  • Candida krusei (correct)
  • Candida albicans
  • Aspergillus spp

    • Cryptococcus neoformans is resistant to Echinocandins.

    True

    What defines virulence in the context of fungi?

    The ability to cause disease.

    Fungal pathogens often evade the human immune system through _____ and _____ of PAMPs.

    <p>polymorphism, masking</p> Signup and view all the answers

    Match the fungal virulence factors with their descriptions:

    <p>Thermotolerance = Ability to grow at 37 degrees C Biofilm formation = Structured assemblies resistant to antifungals Polymorphism = Dimorphic growth adaptability Immune evasion = Strategies to avoid immune detection</p> Signup and view all the answers

    Which mechanism is associated with the azole resistance in fungi?

    <p>Biofilm formation</p> Signup and view all the answers

    Acquired resistance can occur through horizontal gene transfer in fungi.

    <p>False</p> Signup and view all the answers

    What is one of the criteria necessary for a fungus to parasitize humans?

    <p>Ability to digest and absorb components of human tissues.</p> Signup and view all the answers

    The presence of _____ in biofilms contributes to antifungal resistance.

    <p>persister cells</p> Signup and view all the answers

    Which of the following factors can affect the morphogenesis of fungal pathogens?

    <p>Temperature</p> Signup and view all the answers

    What is the primary route of infection for Cryptococcus species?

    <p>Inhalation</p> Signup and view all the answers

    Cryptococcal meningitis only occurs in immunocompromised individuals.

    <p>False</p> Signup and view all the answers

    What are the two main species of Cryptococcus discussed?

    <p>Cryptococcus neoformans and Cryptococcus gattii</p> Signup and view all the answers

    Amphotericin B is primarily administered by ______.

    <p>IV</p> Signup and view all the answers

    Match the following antifungal agents with their mode of action:

    <p>Polyenes = Form pore structures in membranes Azoles = Inhibit ergosterol synthesis 5-Flucytosine = Inhibits protein and DNA synthesis Echinocandins = Inhibit beta1,3-Glucan synthase</p> Signup and view all the answers

    Which antifungal agent is considered a natural compound?

    <p>Polyenes</p> Signup and view all the answers

    Allylamines have good activity against Aspergillus spp.

    <p>False</p> Signup and view all the answers

    What is a significant problem associated with echinocandins?

    <p>Not available orally</p> Signup and view all the answers

    Cryptococcus gattii is known to infect ______ individuals more commonly.

    <p>healthy</p> Signup and view all the answers

    Which antifungal agent inhibits squalene epoxidase?

    <p>Allylamines</p> Signup and view all the answers

    Resistance to antifungal agents is not a concern in clinical settings.

    <p>False</p> Signup and view all the answers

    What is a major clinical use of Flucytosine?

    <p>Treatment of Candida infections</p> Signup and view all the answers

    The mode of action of azoles involves inhibiting the enzyme ______.

    <p>14 alpha sterol demethylase</p> Signup and view all the answers

    Which antifungal is known for having a high mortality rate when treating cryptococcal meningitis?

    <p>Amphotericin B</p> Signup and view all the answers

    Which of the following fungi is classified as a primary pathogen?

    <p>Histoplasma capsulatum</p> Signup and view all the answers

    Fungi are prokaryotic organisms.

    <p>False</p> Signup and view all the answers

    Name one type of superficial mycoses.

    <p>Tinea pedis</p> Signup and view all the answers

    The _____ fungal cell wall is composed of complex polysaccharides like chitin and glucan.

    <p>fungal</p> Signup and view all the answers

    Match the fungal pathogens with the type of mycoses they cause:

    <p>Candida spp = Superficial mycoses Mucormycosis = Subcutaneous mycoses Cryptococcus neoformans = Invasive mycoses Microsporum canis = Superficial mycoses</p> Signup and view all the answers

    Which fungus is known for causing invasive mycoses predominantly in immunocompromised individuals?

    <p>Aspergillus fumigatus</p> Signup and view all the answers

    Most species of Aspergillus are disease-causing.

    <p>False</p> Signup and view all the answers

    What are two examples of opportunistic fungal pathogens?

    <p>Candida spp and Aspergillus spp</p> Signup and view all the answers

    Candida albicans can exist in several forms, including _____, _____, and _____.

    <p>yeast, hyphae, pseudohyphae</p> Signup and view all the answers

    Match the disease caused by Aspergillus to its respective kind:

    <p>Invasive bronchopulmonary Aspergillosis = High mortality Aspergillosis-related allergy = Asthma sufferers Disseminated Aspergillosis = 60-90% mortality</p> Signup and view all the answers

    Which of the following is NOT a characteristic of the fungal cell wall?

    <p>Present in mammalian cells</p> Signup and view all the answers

    Invasive mycoses are less fatal than tuberculosis.

    <p>False</p> Signup and view all the answers

    What are the two major types of fungal pathogens based on the host's immune status?

    <p>Primary and Opportunistic</p> Signup and view all the answers

    Superficial mycoses typically infect ______ rich tissues.

    <p>keratin</p> Signup and view all the answers

    Which of the following fungi is critical priority according to WHO?

    <p>Candida auris</p> Signup and view all the answers

    Study Notes

    Fungal Pathogens, Diseases and Treatments

    • Fungi are eukaryotic organisms, similar in rank to plants and animals.
    • They absorb nutrients by secreting enzymes to break down organic material.
    • Approximately 1.5 million species exist, with 8,000 plant and 600 human pathogens.

    Types of Fungi - Morphology

    • Yeast: Round/oval, non-polymorphic, unicellular (e.g., Saccharomyces cerevisiae, used in fermentation). Multiply by budding, leaving scars on the mother cell. Environmental organisms.
    • Dimorphic/Polymorphic Fungi: Switch between growth forms (reversible, e.g., Candida albicans). Commensal, easily changing shape.
    • Moulds: Obligate filamentous fungi, produce conidia, cannot reverse growth form (e.g., Aspergillus fumigatus). Environmental organisms.
    • Mushrooms: A type of fungus.

    Fungal Cell Wall

    • A key structural component, unique to fungi.
    • Composed of polysaccharides (chitin, glucan, mannan, proteins) forming a robust structure.
    • Protects fungus.
    • Flexible and allows for growth and adaptation.
    • Antifungal drug, immune response, and vaccine targets.

    Types of Fungal Pathogens

    • Primary: Infect healthy individuals (e.g., Histoplasma capsulatum, Blastomyces dermatitidis, Paracoccidioides brasiliensis, Coccidioides immitis). Generally inhaled but sometimes through cuts. Restricted geographical distribution.
    • Opportunistic: Primarily infect immunocompromised patients (e.g., Dermatophytes, Candida spp, Aspergillus spp, Cryptococcus spp). Diverse routes of infection. Global distribution.

    Diseases Caused by Opportunistic Fungi

    • Superficial Mycoses: Non-lethal (e.g., Dermatophytes causing athlete's foot, Candida spp causing thrush). Affects skin, nails, mouth, vagina.
    • Subcutaneous Mycoses: Non-lethal but debilitating (e.g., chromoblastomycosis, Madura foot). Often in individuals without access to quality healthcare. Rare, but challenging to treat.
    • Invasive Mycoses: Lethal, predominantly affecting immunocompromised. Critical priority fungal pathogens include Cryptococcus neoformans, Candida auris, Aspergillus fumigatus, Candida albicans.

    Superficial Mycoses (Detailed)

    • Caused by dermatophytes (Microsporum spp, Epidermophyton spp, Trichophyton spp). Filamentous fungi.
    • Found in soil, animals, and humans. Digest keratin for growth. Infects keratin-rich tissues in skin, hair, and nails.
    • Candida infections are also superficial and can have significant inflammation in "normal individuals".

    Subcutaneous Mycoses (Detailed)

    • Mostly geographically restricted, such as Sporotrichosis and Mucormycosis (some global distribution).
    • Affect subcutaneous tissue, often introduced by skin puncture wounds.

    Invasive Mycoses (Detailed)

    • High mortality rates in immunocompromised patients.
    • Severity depends on immune system status.
    • Roughly equivalent in mortality rate to tuberculosis and malaria.

    Aspergillus Species

    • Most species don't cause disease. A. fumigatus, A. flavus, etc are disease-causing species.
    • Infection through inhalation of spores.
    • Causes a spectrum of disease: allergy, invasive bronchopulmonary aspergillosis, disseminated aspergillosis (high mortality).
    • Risks are higher in patients with pre-existing lung issues (e.g., COPD) or compromised immune systems.

    Candidiasis

    • Candida albicans (polymorphic yeast, hyphae, pseudohyphae) is the primary causative organism. Commensal organism in mucosal and skin microbiota.
    • Infection often from environmental changes, weakened immunity, or sores.
    • Causes superficial (mouth, vagina) and invasive (GI tract, organs, blood) candidiasis.

    Cryptococcosis

    • Cryptococcus neoformans frequently infects immunocompromised individuals. Cryptococcus gattii can infect healthy individuals.
    • Causes pulmonary cryptococcosis (often asymptomatic, chronic).
    • Cryptococcal meningitis is common among immunocompromised patients (e.g., HIV, organ transplant recipients); high mortality.

    Antifungal Agents

    • Polyenes: Disrupt fungal cell membranes (e.g., amphotericin B).
    • Azoles: Inhibit ergosterol synthesis.
    • Allylamines: Inhibit ergosterol synthesis.
    • Flucytosine: Inhibits DNA synthesis.
    • Echinocandins: Inhibit glucan synthesis.

    Antifungal Resistance

    • Mechanisms include alterations in drug targets, overexpression of efflux pumps, and modification of stress responses.
    • Can be intrinsic or secondary (acquired).

    Fungal Virulence Factors

    • Growth at 37°C
    • Biofilm formation
    • Morphogenesis (polymorphism)

    Virulence Factor Identification

    • Approaches include reverse and forward genetics and molecular Koch's postulates.

    Criteria for Fungal Parasitism

    • Growth in host.
    • Reaching target tissues.
    • Digesting/absorbing host components.
    • Withstanding host immune system.

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    Description

    Test your knowledge on the types, structures, and treatments of fungal pathogens. Explore the unique characteristics of yeast, dimorphic fungi, moulds, and mushrooms, while understanding their impact on humans and plants. This quiz covers essential concepts in mycology and fungal diseases.

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