Micro Week 4
92 Questions
11 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is an opportunistic meningoencephalitis that is commonly present in the environment?

  • Cryptococcus neoformans (correct)
  • Lymphocytic choriomeningitis
  • Toxoplasmosis
  • Aseptic meningitis

    • What is a dematiaceous fungus that is darkly pigmented with melanin in its cell wall?

  • Aspergillus niger
  • Chromoblastomycosis (correct)
  • Cladosporium spp.
  • Candidiasis

    • Which molds are known to be colorless or brightly colored?

  • Hyaline (correct)
  • Dermatiaceous
  • Zygomycetes
  • Rhizopus

    • Which of the following has the characteristic of surviving on dead or dying material?

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

    Which of the following has this definition: Mutual advantage of organisms?

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

    What is a serious but rare fungal infection caused by mucormycete molds?

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

    Which stain is a silver stain used for staining fungal organisms?

    <p>Grocott's stain</p> Signup and view all the answers

    What kingdom has the following descriptions:

    • Eukaryote
    • Rigid cell wall: chitin and glucan
    • Cell membrane: ergosterol substituted for cholesterol
    • 2 forms: mold (multicellular), yeast (unicellular)?

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

    What are hyphae?

    <p>Thread-like tubes</p> Signup and view all the answers

    How do hyphae elongate?

    <p>Apical extension</p> Signup and view all the answers

    What kind of hyphae is hollow and multinucleated?

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

    What kind of hyphae is divided?

    <p>Septate hyphae</p> Signup and view all the answers

    In which phylum are a small subset of dimorphic fungi found?

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

    Via which mechanism do blastophores give rise to new material?

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

    What is an example of a mold that contains blastospores?

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

    Match each asexual spore to its definition

    <p>Sporangiospores = Spores produced in a sporangia;Ex. Mucorales order: Rhizopus Conidia = ““naked” spores;Ex. Aspergillus, Penicillium and dermatophytes Zygospore = thick-walled resting cell arising from fusion of two similar gametes Arthroconidia = forms from segmentation of existing fungal hyphae; Coccidiodes</p> Signup and view all the answers

    Which conidium has the following description:

    -Unicellular round, elliptical or pyriform (pear-shaped)?

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

    Which conidia is smooth, cigar-shaped, and is produced in clusters growing directly from hyphae?

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

    Most fungi are strict anaerobes.

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

    Which of the following is not a primary metabolite of fungi?

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

    Which of the following are secondary metabolites produced by fungi?

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

    Which fungi produce aflatoxins?

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

    Fungi are fast growing.

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

    Match each fungus to its infection

    <h1>Superficial mycoses = Tinea pedis (athlete's foot) Subcutaneous mycosis = sporotrochosis (caused by a skin puncture from thorns or vegetation contaminated with fungi) Systemic mycosis = coccidioides immitis (desert fever)</h1> Signup and view all the answers

    What are dermatophytes?

    <p>Fungi that grow in tissues that contain keratin: limited to skin, hair and nails</p> Signup and view all the answers

    What kind of fungal infection inflammatory response is described as 'ringworm' or 'tinea'?

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

    How are dermatophyte infections diagnosed?

    <p>Finding septate hypha and asexual spores in scraping of tissue</p> Signup and view all the answers

    Which of the following is not one of the three dermatophyte genera?

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

    Nail invasion by non-dermatophyte molds is uncommon.

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

    Which of the following is a nondermatophytic mold?

    <p>Aspergillus sp.</p> Signup and view all the answers

    Which fungal infection causes onychomycosis and lower extremity skin lesions in patients with neutropenia?

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

    What fungal infection causes sinus infections in diabetic patients with ketoacidosis?

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

    Match each stain to its description

    <h1>Gram stain = most stain gram positive, except Cryptococcus neoformans – exhibit stippling or appear gram-negative Giemsa stain = can stain for intracellular pathogens: H. capsulatum and P. jirovecii (cannot stain cyst wall) – and other fungi that are intracellular Calcofluor white stain = can detect all fungi; detects fungal cell wall chitin by bright fluorescence</h1> Signup and view all the answers

    Which two media must be used for a fungi cell culture?

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

    What organism is modified Dixon agar used to diagnose?

    <p>Malassezia furfur</p> Signup and view all the answers

    Which fungi require blood in the culture for diagnosis?

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

    What can be added to agar that enables direct detection of specific enzymes in fungal culture?

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

    What method is commonly used to identify C. albicans, C. tropicalis, and C. krusei?

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

    What does the specific CHROMagar for C. albicans target?

    <p>beta-galactose-aminidase</p> Signup and view all the answers

    At what temperature is fungal growth considered potentially infectious?

    <p>37°C</p> Signup and view all the answers

    At which temperature do most fungi grow?

    <p>20-30°C</p> Signup and view all the answers

    What is DMASP?

    <p>The probe that can penetrate fungal cell walls and is used to measure fungal presence in assay</p> Signup and view all the answers

    Match each stain to its description

    <h1>MS (Gomori methenamine silver) = best stain for all fungi. Stains hyphae and yeast forms black against a green background PAS (periodic acid shift) = can stain hyphae and yeast; artifacts in stain may resemble yeast cells: false positive Mucicarmine = stains mucin such as capsule ofC. neoformans</h1> Signup and view all the answers

    What is found in the cell walls of patients infected with Candida, Aspergillus, and P. jirovecii?

    <p>1, 3-Beta-glucan</p> Signup and view all the answers

    Which of the following are immunological methods for diagnosis? (Select all that apply)

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

    What does D-arabinitol in serum indicate?

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

    What does the presence of D-mannitol in bronchoalveolar lavage suggest?

    <p>Pulmonary aspergillosis</p> Signup and view all the answers

    What is an example of a molecular marker?

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

    How is blastomycosis infection acquired?

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

    Infections of which of the following organisms are associated with moist soil in river valleys?

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

    Infections with which of the following are associated with dry soil and desert areas?

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

    Which dimorphic mycosis has the following epidemiology:

    • Endemic in Southeastern and South-Central states, especially bordering Ohio and Mississippi river basins; Midwestern states and Canadian provinces on Great Lakes; New York and Canada along the Lawrence River.
    • Outbreaks are associated with occupational or recreational contact.
    • Person-to-person spread does not occur?

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

    Which dimorphic mycosis has the following description:

    • Life cycle: Saprobic (mold); Parasitic (yeast) – transmission inhale conidia spores
    • Characteristics: Mold form are septate hyphae and oval or pyriform single-celled conidia at tips of short or long conidiophores resemble lollipops; Yeast have double thick walls with broad based budding?

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

    Which dimorphic mycosis is described by the following characteristics?

    -Diagnostic: • Microscopic detection of yeast cells • Antigen detection in the urine • Grows as mold (room temp) 2-4 weeks • Grows as a yeast (37°) 3-5 days

    -Treatment: • Intraconazole for mild to moderate symptoms – prevents ergosterol synthesis • Amphotericin B for severe lung or disseminated infections – binds ergosterol in the fungal cell membrane and makes holes.

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

    Which dimorphic mycosis has the following description:

    • Can only be differentiated by molecular methods; Forms a spherule containing endospores in humans.

    • Key to diagnosis: Has a unique mold form; does not form spores at the end of hyphae; growing mycelia are subdivided by septae (walls); alternating cells will disintegrate leaving barrel-shaped cells (arthroconidia); arthroconidia are infectious spores resilient to harsh environments; spores can be carried hundreds of miles in wind currents.

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

    Which dimorphic mycosis has the following description:

    -Life cycle • Saprobic (mold) • Parasitic (spherule) • Triad – desert rheumatism – combination of fever, joint pains and erythema nodosum • 3-5% develop chronic infection • Chronic infection if untreated can disseminate • Mortality is high; untreated is fatal in 90% of patients in one year and 100% in 2 years; 20-40% fatal with treatment?

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

    Which dimorphic mycosis has the following description:

    • Epidemiology • Endemic to US South West desert, northern Mexico, areas of Central and South America • Spores can survive for extended periods and disseminate via wind • Asymptomatic infection is common • Risk of dissemination in certain ethnic groups: Filipino, African American, Native American, Hispanic; individuals in the 3rd trimester of pregnancy, and immune deficient individuals • No person-to-person spread • Lab infections can occur, so caution is required in handling the mold?

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

    Which dimorphic mycosis has the following description:

    -Diagnosis • Endosporulating spherules in tissues, sputa, or wound drainage • Mold form grows rapidly in culture (1-2 days); caution due to the highly infectious nature of spores

    • Treatment • 3-6 months with fluconazole (Diflucan) or itraconazole (Sporanox, Tolsura)?

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

    Which dimorphic mycosis has the following description:

    -Epidemiology • Var. capsulatum: Ohio and Mississippi river valleys; Mexico and central and south America • Var. duboisii: tropical Africa • Found in soil with high nitrogen content (bird/bat droppings) • Person-person transmission does not occur • Immune compromised patients and children are most susceptible?

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

    Which variants of Histoplasma capsulatum lead to pulmonary and disseminated disease in Eastern USA and Latin America?

    <p>H. capsulatum var. capsulatum</p> Signup and view all the answers

    Which histoplasma capsulatum variant leads to skin and bone lesions in tropical areas of Africa?

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

    Which Histoplasma capsulatum variant is thin-walled?

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

    Which Histoplasma capsulatum variant is thick-walled?

    <p>H. capsulatum var. duboisii</p> Signup and view all the answers

    Which dimorphic mycosis is described by the following characteristics?

    -Natural History • Saprobic (mold) • Parasitic (yeast)

    • Clinical Disease • Severity depends on extent of exposure and immune status • Most are asymptomatic or mild (flu-like symptoms) • Acute pulmonary infection usually resolves in 10 days but can disseminate and involve multiple organs.

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

    Which dimorphic mycosis has the following characteristics: Diagnosis includes direct microscopy and culture of respiratory material; serology is useful except in AIDS patients; and detection in urine or serum is useful in extrapulmonary disease? The treatment typically involves clearance by cell-mediated immunity and using itraconazole for 3 months to 1 year.

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

    Match each organism to its description

    <p>Candida albicans = the most common yeast that causes opportunistic fungal diseases Aspergillus fumigatus = the most common mold that causes opportunistic fungal diseases Cryptococcus neoformans = the most common cause of fungal meningitis Pneumocystis jiroveaci = the most common opportunistic pathogen in AIDS patients</p> Signup and view all the answers

    What are immunocompromised patients with Candida treated with?

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

    What fungal organism has the following description:

    • Natural history of infection: Saprobic and parasitic forms
    • Clinical Disease: • Initially develops in lungs, dissemination to blood and CNS is common • Meningitis is usually the presenting disease?

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

    Which fungal organism is described by the following characteristics?

    • Diagnosis: • Definitive diagnosis by culture of the organism in blood, sputum, or CSF (most reliable source) • Microscopic examination of CSF demonstrates budding cells (India ink as contrast dye) • Use of antigen test to detect polysaccharide capsule material

    • Treatment/control/prevention: • Meningitis is fatal if not treated • Amphotericin B and fluconazole used first • Maintenance by fluconazole or itraconazole • Antigen test monitors response to therapy • Prophylactic use of antifungals is recommended for high-risk patients

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

    Which fungal organism is described as:

    • Yeast-like fungi
    • Associated with catheter-related sepsis
    • Especially in patients receiving lipid infusions
    • Treated by removal of catheter line and discontinuation of lipid infusions?

    <p>Malassezia furfur</p> Signup and view all the answers

    Which fungal organism has the following description:

    -Most common mold that causes opportunistic infections • Many species but those associated with human disease are limited • Inhalation of spores produces wide range of disease?

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

    Which fungal organism is associated with the following descriptions:

    • Chronic pulmonary disease includes spherules and long-term azole therapy.
    • Involves voriconazole or amphotericin B for treatment
    • Prophylaxis of high-risk patients includes itraconazole, posaconazole, or voriconazole.
    • Exposure is difficult to control since mold is in the environment; high-risk patients should avoid areas of remodeling, construction, and excavation.

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

    Match each organism to its description

    <h1>Mucorales ( Rhizopus, Mucor, Rhizomucor) = Nonseptated, nonpigmented molds cause invasive disease in immune compromised patients particularly diabetics, patients with metabolic acidosis, hematologic malignances Fusarium, Scedosporium, Paecilomyces = Septated nonpigmented molds cause dissemination in immune compromised patients; note: can be isolated from blood Alternaria, Bipolaris, Curvularia = Septated, pigmented mold cause localized subcutaneous disease following trauma or disseminated to multiple organs in immune compromised patients</h1> Signup and view all the answers

    Which subcutaneous mycosis has the following description:

    -a fungus found in sphagnum moss, organic-rich soil, and rotting veggies. Infection occurs when the fungus is introduced into subcutaneous tissues through cuts in the skin (thorns). -produces painless, nonhealing ulcers on the skin surface?

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

    Which subcutaneous mycosis is characterized by skin ulcers at the primary site of inoculation of Sporothrix schenckii, with lesions developing along lymphatics and presenting as lymphocutaneous disease?

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

    Which subcutaneous mycosis has the following description:

    -Diagnosis • Demonstrate yeast form in lesions is difficult • Dimorphic fungus with cigar-shaped yeast cells in lesions when observed and classic mold in lab culture at 25-30°C • Mold has thin hyphae and budding spores that look like a flower (flowerette)?

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

    Which subcutaneous mycosis has the following description:

    • Chronic fungal infection of skin and subcutaneous tissues
    • Slow growing plaques “cauliflower-like”
    • Disfiguring with secondary lesions and infections
    • Fonsecaea, Cladosporium, Exophiala and many pigmented molds (dematiaceous)
    • All form Medlar bodies that are brown due to melanin in their cell walls?

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

    What is a mycetoma?

    <p>chronic progressively destructive infectious disease of SQ tissue that spreads to affected skin, deep tissues and bones</p> Signup and view all the answers

    Which mycetoma has the following description: there may be multiple punched out lytic lesions in bones whereas actinomycotic mycetoma is characterized by both osteolytic and osteosclerotic lesions, resulting in gross swelling of the affected part with deformity?

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

    When is mycetoma classified as eumycetoma?

    <p>When caused by saprophytic fungi</p> Signup and view all the answers

    What is the most common eumycetoma?

    <p>Madurella mycetomatis</p> Signup and view all the answers

    When is mycetoma classified as Actinomycetoma?

    <p>When it involves bacterial infection</p> Signup and view all the answers

    What is the most common Actinomycetoma?

    <p>Nocardia Actinomycetoma</p> Signup and view all the answers

    What do black grains in mycetoma indicate?

    <p>Infection with a black fungus</p> Signup and view all the answers

    What do red grains in mycetoma indicate?

    <p>Presence of Actinomyces pelletieri</p> Signup and view all the answers

    How are Actinomyces infections primarily treated?

    <p>Antibiotics such as penicillin</p> Signup and view all the answers

    How are Nocardia infections typically treated?

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

    What is the ratio of males to females infected by subcutaneous mucormycosis?

    <p>8:1</p> Signup and view all the answers

    Which subcutaneous mucormycosis has the following description:

    • spherical conidia with hair-like projections – rhinofacial disease in immunocompetent hosts; some only in immunocompromised patients?

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

    Which mucormycosis has the following description: restricted to subcutaneous tissues but can be involved in intestinal and disseminated infections?

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

    Which organism is characterized by the following description:

    • Single inflammatory cyst on feet or legs (hands too but less common)
    • Grows slowly over years
    • Associated with Exophilia, Alternaria, Curvularia, and dematiaceous molds
    • Shows Splendore-Hoeppli phenomenon with intense eosinophilic staining and star-like, asteroid or club-shaped configurations around microorganisms (fungi, bacteria, parasites) or inert objects?

    <p>Subcutaeous Phaeohyphomycosis</p> Signup and view all the answers

    Match each fungus to its disease

    <p>Malassezia furfur = Tinea versicolor Hortaea werneckii = Tinea nigra Trichosporon spp. = White Piedra Piedraia hortae = Black Piedra</p> Signup and view all the answers

    Study Notes

    Opportunistic Infections and Fungal Characteristics

    • Opportunistic meningoencephalitis is frequently found in the environment, often caused by fungi or protozoa in immunocompromised individuals.
    • Dematiaceous fungi are characterized by their dark pigmentation due to melanin in their cell walls.
    • Molds can be colorless or vividly colored, with some exhibiting bright pigments in their conidial structures.
    • Various fungi are saprophytic, meaning they thrive on dead or decaying organic matter.

    Mutualistic Relationships and Fungal Infections

    • Mutual advantage among organisms refers to symbiosis, where both benefit from their relationship.
    • Mucormycosis is a rare but serious fungal infection caused by molds belonging to the Zygomycetes class.
    • Silver stain is commonly used for staining fungal organisms, making them more visible under a microscope.

    Fungal Kingdom Characteristics

    • The fungal kingdom comprises eukaryotic organisms with rigid cell walls primarily made of chitin and glucan; they have ergosterol instead of cholesterol in their membranes.
    • Fungi can exist in two forms: mold (multicellular) and yeast (unicellular).

    Hyphae Structure and Growth

    • Hyphae are the filamentous structures that make up fungi, crucial for nutrient absorption and growth.
    • Hyphae elongate through a process of tip growth, where new cell wall material is added at the growing tip.
    • Coenocytic hyphae are hollow and multinucleated, while septate hyphae are divided by cross walls or septa.

    Dimorphic Fungi and Reproduction

    • A small subset of dimorphic fungi can be found in the phylum Ascomycota.
    • Blastospores arise through budding, a mechanism by which yeast cells reproduce.
    • An example of a mold producing blastospores is Saccharomyces cerevisiae.

    Asexual Spores and Fungal Metabolism

    • Unicellular, round, elliptical, or pear-shaped conidia are typically referred to as microconidia.
    • Macroconidia are smooth, cigar-shaped, and produced in clusters directly from hyphae.
    • Most fungi are classified as aerobic, with primary metabolites including enzymes and organic acids; secondary metabolites include fungal toxins like aflatoxins produced by Aspergillus species.

    Dermatophytes and Fungal Infections

    • Dermatophytes are fungi causing skin infections like ringworm (tinea), characterized by inflammatory lesions.
    • Diagnosis of dermatophyte infections typically involves culture and examination of skin, hair, or nails.
    • Non-dermatophytic molds can invade nails and skin but are less common than dermatophytes.
    • Fungi can be cultured using media such as Sabouraud agar and blood agar; they require specific environmental conditions for growth.
    • Dixon agar is specifically used to diagnose Candida infections.
    • Specific enzymes can be detected on agar plates using chromogenic substrates for identification.

    Dimorphic Mycoses and Clinical Presentation

    • Coccidioidomycosis is endemic to the southwestern US and characterized by a saprobic mold phase and a parasitic yeast form upon inhalation of spores.
    • Blastomycosis is diagnosed by detecting yeast cells microscopically or through antigen detection; it requires prolonged treatment.
    • Histoplasmosis has distinct variants based on geographic distribution, particularly affecting immune-compromised individuals.

    Treatment and Management of Fungal Infections

    • Antifungal treatment varies; azoles inhibit ergosterol synthesis while amphotericin B disrupts fungal cell membranes.
    • Persistent infections such as pulmonary aspergillosis require long-term azole therapy and have a significant impact on immunosuppressed patients.

    Subcutaneous Mycoses Characteristics

    • Sporothrix schenckii is associated with traumatic inoculation through skin and produces lymphocutaneous infections characterized by progressive ulcers.
    • Eumycetoma is classified based on the presence of eukaryotic fungal grains, while actinomycetoma involves bacterial pathogens.

    Special Considerations in Mycotic Infections

    • Mycetoma is classified based on the morphology of the grains; black grains indicate eumycetoma, whereas red grains indicate actinomycetoma.
    • Actinomyces infections require appropriate antibiotic treatment, while Nocardia infections often necessitate prolonged therapy with sulfonamides.
    • Subcutaneous mucormycosis manifests as infections typically localized to skin and soft tissues, with specific forms associated with immunocompromised conditions.
    • Patients with chronic infections can present unique clinical features, including development of grand lesions and immunological responses.

    General Observations

    • Most fungi thrive in specific environments; for example, certain strains of Candida require lipid sources for growth, while many molds are naturally occurring in soil.
    • The epidemiology of tropical mycoses extends to varied geographic locations, highlighting unique risks for certain populations and environmental exposures.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Test your knowledge on opportunistic meningoencephalitis, a disease that is commonly found in the environment. This quiz explores its causes, symptoms, and treatment options. Perfect for students and professionals in the field of medicine and microbiology.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser