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Questions and Answers
Which diagnostic method is used to observe the yeast morphology of Paracoccidioides brasiliensis?
Which treatment option is a component of the long-term therapy for Paracoccidioides brasiliensis infection?
What is the primary pathogen causing South American blastomycosis?
What appearance do the thick-walled yeasts of Paracoccidioides brasiliensis exhibit under histopathological staining?
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Penicilliosis primarily affects individuals with which immunological condition?
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Which of the following fungi is primarily responsible for causing candidiasis?
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What is a common cause of immunocompromised conditions that can lead to systemic fungal infections?
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What diagnostic method is most reliable for confirming fungal infections?
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Which of the following antifungal agents is NOT typically used for the treatment of cryptococcosis?
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Which type of fungal infection is classified as zygomycosis?
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Which of the following symptoms is associated with Aspergillosis?
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What type of pathogen is most likely to cause systemic infections in immunocompromised individuals?
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Which treatment is effective for zygomycosis?
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Which of the following characteristics are true for Coccidioides species?
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What is the purpose of the immunodiffusion test in diagnosing fungal infections?
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What type of fungal pathogen is primarily transmitted through inhalation of conidia?
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Which treatment option is preferred for life-threatening infections caused by fungal pathogens?
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What symptom is commonly associated with pulmonary infections from Blastomyces dermatitidis?
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What does the 120-kDa glycoprotein BAD-I primarily function as in Blastomyces dermatitidis?
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Which method is more sensitive in detecting Blastomyces antigens in patients?
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How is delayed hypersensitivity reaction confirmed in patients exposed to fungal infections?
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Study Notes
Antifungal Drugs
- Ketoconazole, Itraconazole, Miconazole, Flucytosine, and Amphotericin B are common antifungal drugs.
- Topical clotrimazole, topical nystatin, fluconazole, and topical ketoconazole are used to treat candidiasis.
- Voriconazole and liposomal amphotericin B are used to treat aspergillosis.
- Amphotericin B and flucytosine are used to treat cryptococcosis.
- Amphotericin B, Fungizone, amphocine, ambisome, and liposomal amphotericin B are used to treat zygomycosis.
Systemic Mycoses
- Systemic mycoses are fungal infections that only affect immunocompromised or sick individuals.
- Systemic mycoses can occur in people with AIDS, altered normal flora from antibiotics, immunosuppressive therapy, and metastatic cancer.
- Systemic mycoses include candidiasis, aspergillosis, cryptococcosis, and zygomycosis
Candidiasis
- Caused by yeast-like fungi of the Candida genus, most commonly Candida albicans.
- There are two types: infectious and allergic.
- Symptoms vary based on the affected area, but common symptoms include redness, itching, and discomfort.
Aspergillosis
- Caused by Aspergillus fumigatus.
- Aspergillus has the tendency to invade blood vessels.
- Symptoms include superficial lesions, coughing up blood, and chest pain.
Cryptococcosis
- Caused by Cryptococcus neoformans.
- Cryptococcus neoformans is an encapsulated yeast found in soil and bird droppings, especially pigeon droppings.
- Symptoms include pneumonia-like illness, shortness of breath, skin lesions, fever, and cough.
Zygomycosis
- Also known as mucomycosis.
- Caused by infections from the Zygomycetes class, also known as Phycomycetes.
- Symptoms include facial swelling, bulging eyes, headache, blurred and double vision, and bleeding from the nose.
Risk Factors for Systemic Mycoses
- Human immunodeficiency virus (HIV) infection.
- Systemic malignancy (cancer).
- Neutropenia (low white blood cell count).
- Organ transplant recipients.
- Individuals who have recently undergone major surgery.
- Uncontrolled diabetes mellitus.
- Very young or very old individuals.
Diagnosis of Systemic Mycoses
- The most reliable tests for diagnosis are skin biopsy for microscopic analysis and fungal culture.
- Blood can also be cultured.
Molecular Methods for Diagnosis
- DNA probe hybridization.
- Real-time polymerase chain reaction (PCR).
Blastomycosis
- Also known as South American blastomycosis or Lutz-Splendore-de Almeida disease.
- Caused by the dimorphic fungus Paracoccidioides brasiliensis.
- It is an acute or chronic, granulomatous infection primarily affecting the lungs. It can disseminate to the skin, mucosa, and other internal organs.
- Symptoms include acute pneumonia.
- Treatment involves long-term therapy with amphotericin B combined with sulfonamides or oral itraconazole.
Histoplasmosis
- Histopathological staining reveals thick-walled round yeast cells of 8-15 µm in size with single broad-based budding.
- Histoplasmosis can be cultured on SDA, blood agar, and BHI.
- At 25°C, the mycelial form containing hyphae with small pear-shaped conidia are produced.
- At 37°C, the mold converts to yeast.
- Skin testing can demonstrate delayed-type hypersensitivity to blastomycin antigen.
Paracoccidioidomycosis
- Also known as South American blastomycosis, Lutz-Splendore-de Almeida disease.
- Systemic disease caused by the dimorphic fungus Paracoccidioides brasiliensis.
- Acute or chronic, granulomatous infection of the lungs that may disseminate to the skin, mucosa, and other internal organs.
- Symptoms include acute pneumonia.
- Treatment involves long-term therapy with amphotericin B combined with sulfonamides or oral itraconazole.
Histopathological Staining of Paracoccidioidomycosis
- H & E stain, PAS, or CMS of sputum or tissue biopsy specimens demonstrate spherules, which are large sac-like structures (20-80 µm in size) with thick, double refractile walls filled with endospores.
Culture of Paracoccidioidomycosis
- Culture on SDA produces mycelial growth at 25°C.
- Conversion to the yeast phase occurs at 37°C when grown in BHI agar supplemented with blood and glutamine.
Serology of Paracoccidioidomycosis
- Antibodies are detected by immunodiffusion and ELISA using gp43 antigen of P. brasiliensis.
Skin Test for Paracoccidioidomycosis
- Demonstrates delayed hypersensitivity response against paracoccidioidin antigen.
Penicilliosis
- Caused by Penicillium marneffei.
- Penicilliosis typically affects individuals with AIDS and low CD4 lymphocyte counts.
- Symptoms include fever, skin lesions, anemia, and lymphadenopathy.
Histopathological Staining of Penicilliosis
- H & E stain, PAS, or CMS of sputum or tissue biopsy specimens demonstrate spherules, which are large sac-like structures (20-80 µm in size) with thick, double refractile walls filled with endospores.
Culture of Penicilliosis
- Cultures on SDA produce mycelial growth described as fragmented hyphae consisting of barrel-shaped arthrospores with alternate cells distorted (empty cells).
- Coccidioides differs from other dimorphic fungi as it grows as mold at both 25°C and 37°C in usual culture media (forms spherules at 37°C in certain special culture media only).
- Cultures are highly infectious and require biosafety level-3 precautions due to accidental inhalation of spores in laboratories.
Serology of Penicilliosis
- Antibodies are detected by immunodiffusion test and CFT.
Skin Test for Penicilliosis
- Performed by fungal extracts (coccidioidin or spherulin).
- A reaction of at least 5 mm induration within 48 hours after injection (delayed hypersensitivity reaction) indicates past infection.
Blastomycosis
- Also known as North American blastomycosis, Gilchrist's disease, or Chicago disease.
- Caused by the dimorphic fungus Blastomyces dermatitidis.
- Fungal infection of humans and other animals, including dogs and cats.
- Lung infection can occur after inhaling airborne, microscopic fungal spores from the environment.
- Symptoms include fever, chills, cough, muscle ache, joint pain, and chest pain.
Treatment of Blastomycosis
- Initial phase: Oral ketoconazole or itraconazole.
- Life-threatening infections: Amphotericin B (AMB).
Transmission of Blastomycosis
- Transmitted by inhalation of conidia of B. dermatitidis.
- Spores enter the lungs, are engulfed by alveolar macrophages, and convert to the yeast phase.
- The yeast expresses a 120-kDa glycoprotein called BAD-I (B. dermatitidis adhesin-1), which is an essential virulence factor and induces cellular and humoral immune responses.
Antibody Detection in Blastomycosis
- Immunodiffusion test specific for B. dermatitidis has been developed against yeast phase antigens such as antigen-A, BAD-I, and ASWS antigen (alkali soluble water soluble).
Antigen Detection Assay for Blastomycosis
- Commercially available, detects Blastomyces antigen in urine (more sensitive) and serum.
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Description
This quiz covers important antifungal drugs and their uses in treating systemic mycoses, including candidiasis, aspergillosis, cryptococcosis, and zygomycosis. Learn about specific medications used for different fungal infections and understand how they impact immunocompromised patients. Test your knowledge on the classifications and applications of these drugs.
