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What does a positive response for Lactose indicate in a physiological test?
What does a positive response for Lactose indicate in a physiological test?
Which physiological test result indicates the presence of myo-Inositol?
Which physiological test result indicates the presence of myo-Inositol?
What does the presence of Glucosamime Glucoside suggest?
What does the presence of Glucosamime Glucoside suggest?
Which of the following sugar tests would yield a positive response for Sucrose?
Which of the following sugar tests would yield a positive response for Sucrose?
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What does a negative result for Nitrate indicate in the physiological tests?
What does a negative result for Nitrate indicate in the physiological tests?
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In physiological tests for carbohydrate utilization, what does a positive response for Melibiose signify?
In physiological tests for carbohydrate utilization, what does a positive response for Melibiose signify?
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What is the significance of the colony characteristics of Malassezia furfur?
What is the significance of the colony characteristics of Malassezia furfur?
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What is a common diagnosis method for detecting Malassezia furfur?
What is a common diagnosis method for detecting Malassezia furfur?
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What physiological test result would indicate the utilization of D-Gluconate?
What physiological test result would indicate the utilization of D-Gluconate?
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Which cellular morphology is associated with Trichosporon inkin?
Which cellular morphology is associated with Trichosporon inkin?
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What characteristic fluorescence color would a Wood's lamp show when examining lesions or hair?
What characteristic fluorescence color would a Wood's lamp show when examining lesions or hair?
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What is a typical appearance of yeast colonies in microscopic examination?
What is a typical appearance of yeast colonies in microscopic examination?
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What type of culture medium is used for cultivating fungi that require lipids?
What type of culture medium is used for cultivating fungi that require lipids?
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Which microscopic feature characterizes older hyphal colonies?
Which microscopic feature characterizes older hyphal colonies?
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What is the 'spaghetti and meatball' appearance associated with?
What is the 'spaghetti and meatball' appearance associated with?
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What typical diagnostic feature is present in chromoblastomycosis?
What typical diagnostic feature is present in chromoblastomycosis?
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What type of conidia are found during the young culture stage in microscopic examinations?
What type of conidia are found during the young culture stage in microscopic examinations?
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What type of morphology indicates the conidiogenesis process during examination?
What type of morphology indicates the conidiogenesis process during examination?
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Which specimen is NOT used for the diagnosis of Histoplasmosis?
Which specimen is NOT used for the diagnosis of Histoplasmosis?
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What is the mode of transmission for Coccidioidomycosis?
What is the mode of transmission for Coccidioidomycosis?
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Which treatment is indicated for severe cases of Histoplasmosis?
Which treatment is indicated for severe cases of Histoplasmosis?
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Which microscopic feature is characteristic of Histoplasma capsulatum?
Which microscopic feature is characteristic of Histoplasma capsulatum?
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Which test is commonly used in the serological diagnosis of fungal infections?
Which test is commonly used in the serological diagnosis of fungal infections?
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What characteristic is associated with the antibiotic production of Penicillium?
What characteristic is associated with the antibiotic production of Penicillium?
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What structural feature is indicative of Coccidioides immitis upon microscopic examination?
What structural feature is indicative of Coccidioides immitis upon microscopic examination?
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Which fungal species is often recognized by producing glabrous or woolly colonies?
Which fungal species is often recognized by producing glabrous or woolly colonies?
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What is the main mode of transmission for Histoplasma capsulatum?
What is the main mode of transmission for Histoplasma capsulatum?
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Which morphological characteristic helps identify microconidia?
Which morphological characteristic helps identify microconidia?
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What serological tests are used for diagnosing Histoplasmosis?
What serological tests are used for diagnosing Histoplasmosis?
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Which feature is NOT associated with Blastomyces dermatitidis?
Which feature is NOT associated with Blastomyces dermatitidis?
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Which microscopic morphology does Paracoccidioides brasiliensis exhibit?
Which microscopic morphology does Paracoccidioides brasiliensis exhibit?
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Study Notes
Physiological Tests for Fungi
- Glucose, melibiose, D-glucitol are positive for Malassezia furfur.
- L-rhamnose and D-glucitol are negative for Trichosporon inkin.
- Galactose, raffinose, α-methyl-D-glucoside are positive for Trichosporon inkin.
- L-sorbose, melezitose, N-acetyl-D-glucosamine, D-gluconate are mostly positive for Trichosporon inkin.
- Sucrose, soluble starch, glycerol, DL-lactate are mostly negative for Trichosporon inkin.
- Maltose, D-xylose, erythritol are positive for Trichosporon inkin.
- Cellobiose and L-arabinose are positive for Trichosporon inkin.
- Ribitol and nitrate are negative for Trichosporon inkin.
- Trehalose, D-arabinose, galactitol are positive for Trichosporon inkin.
- 2-keto-D-gluconate is negative for Trichosporon inkin.
- Lactose, D-ribose, and D-mannitol are positive for Trichosporon inkin.
- D-glucuronate is positive for Trichosporon inkin.
Malassezia furfur
- Also known as Tinea versicolor, Pityriasis versicolor, Dermatomycosis furfuracea, tinea flava, chromophytosis.
- Colonies are restricted, white, finely cerebriform with a granular covering, without a marginal zone, often cracking the media; yellow to brown color species.
- Laboratory diagnosis involves KOH/PAS preparation of skin scrapings.
Trichosporon spp. vs. Aspergillus spp.
- Trichosporon spp. have correctly formed septate tissue; Aspergillus spp. do not.
- Trichosporon spp. have a low disease-causing ability; Aspergillus spp. have high disease-causing ability.
- Penicillium spp. are commonly used in antibiotic production; Aspergillus spp are not popular in antibiotic production.
Rhizopus (Bread Mold)
- Specimen for diagnosis: sputum, urine, scrapings from lesions, bone marrow biopsy, skin, lymph nodes.
Histoplasma capsulatum
- Morphology: microscopic small, ovoid cells intracellularly in histologic sections; stained with Gomori methanamine silver or Giemsa stain.
- Macroconidia: thick-walled, spherical structures (8-15 μm diameter) with surface projections.
- Microconidia: smooth, spherical structures (2-4 μm diameter).
- Disease: Histoplasmosis.
- Miscellaneous tests: serological tests (immunodiffusion, latex agglutination test).
- Mode of transmission: inhalation of conidia.
- Pathogenesis: intracellular mycosis of the reticuloendothelial system; infection is self-limited; symptoms include fever, chills, myalgias, headaches, non-productive cough; severe disseminated histoplasmosis involves the reticuloendothelial system with lymphadenopathy, enlarged spleen, liver, high fever, and anemia.
- Treatment: Amphotericin B.
- Colony characteristics (SDA): white to tan cottony colonies; pale yellow-brown on reverse.
Coccidioides immitis
- Disease: Coccidioidomycosis.
- Mode of transmission: inhalation of airborne arthroconidia.
- Pathogenesis: infection is self-limited; dissemination is rare but may be fatal.
Blastomyces dermatitidis
- Patients with primary infection are often asymptomatic.
- Symptoms: fever, malaise, cough, headache.
- Late-stage patients may have hypersensitivity reactions such as erythema nodosum or erythema multiforme (rashes).
- Specimen for diagnosis: sputum, pus, CSF, tissue biopsy material.
- Morphology: microscopic spherule with thick, doubly refractile wall; endospores form within the spherule and fill it.
- Macroconidia: globose (8-15 μm) with distinctive tuberculate or finger-like cell wall ornamentation.
- Microconidia: ovoid (2-4 μm), smooth or finely roughened.
- Miscellaneous tests: serological tests (immunodiffusion, latex agglutination test).
- Macroscopic morphology (22°C): slow to moderate growth; white to dark tan young colonies, tenacious; old colonies glabrous to wooly.
- Microscopic morphology (22°C): oval, pyriform to globose smooth conidia borne on short, lateral hypha-like conidiophores.
- Microscopic morphology (BAP at 37°C): large yeast (8-12 μm); blastoconidia attached by broad base; small, oval yeast (2-5 μm).
- Colony characteristics (SDA): white to tan colony.
Paracoccidioides brasiliensis
- Macroscopic morphology (22°C): slow growth; white to beige colony; glabrous, leathery, flat to wrinkled, folded, or velvety.
- Microscopic morphology (22°C): colonies frequently produce only sterile hyphae; fresh isolates may produce conidia similar to those of Blastomyces dermatitidis.
Phialophora verrucosa
- Type of mycosis: subcutaneous.
- Causative agent of chromoblastomycosis: verrucous nodules that often become ulcerated and crusted.
- Diagnosis: presence of characteristic lesions accompanied by microscopic sclerotic bodies (copper pennies).
- Macroscopic morphology: dry, smooth or lightly wrinkled, glistening or dull.
- Microscopic morphology: presence of collarettes during conidiogenesis.
Unidentified Fungus (Likely Malassezia sp.)
- Wood's lamp fluorescence: golden yellow to light green fluorescence in lesions/hair.
- Microscopic examination (KOH): round budding yeast cells with hyphae.
- Microscopic examination (PAS): "spaghetti and meatball appearance".
- Culture (SDA): must be overlaid with olive, peanut, or vegetable oil due to lipophilic nature; colonies are shiny, moist, yeast-like, dirty white-brown coloration, eventually turning olive to greenish black.
- Microscopic examination (young cultures): budding blastoconidia.
- Microscopic examination (old cultures): clusters of blastoconidia.
- Microscopic examination (older hyphal colonies): annelloconidia.
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