Fungal Infections: Morphology and Diagnosis

Fungal Infections

• Septate hyphae are characteristic of Phialophora richardsiae
• Aspergillus fumigatus and Histoplasma capsulatum can exhibit both mold and yeast forms
• Aspergillus hyphae can invade nearby tissues

DERMATOPHYTES

• KOH (potassium hydroxide) and Wood's Lamp Examination are diagnostic tools

PITRYIASIS (TINEA) VERSICOLOR

• Characterized by a "Spaghetti and Meatballs" appearance of Malassezia on microscopy

SPOROTHRIX SCHENCKII

• Primary site of infection shows ulceration
• Fungus can spread through the lymphatic vessel, causing new ulcers to appear
• Traumatic injury to the skin (e.g., thorn prick) can introduce the fungus
• Cigar-shaped yeasts are visible on microscopy

CANDIDA

• Yeast cells and pseudohyphae are "yeast" forms, while germ tubes are "hyphae" of Candida albicans
• Causes oral thrush, esophageal thrush, candida vaginitis, intertrigo, and diaper rash

ASPERGILLUS

• Aspergillus hyphae can invade nearby tissues, causing invasive aspergillosis
• Can invade the lung, causing aspergilloma (a "fungus ball" in existing lung cavities) or allergic bronchopulmonary aspergillosis (an asthma-like condition)
• Can also invade the brain tissue

ZYGOMYCETES

• Zygomycetes molds are present in decaying organic matter
• Can cause chronic sinusitis and orbital cellulitis (skin infection)

PNEUMOCYSTIS

• Causes pneumocystis pneumonia, characterized by disc-shaped cysts

CRYPTOCCOCUS

• Characterized by thick capsules
• Causes cryptococcal pneumonia and cryptococcal meningoencephalitis (beginning with fever, fatigue, and headache, and later causing confusion and behavioral changes)

CASE STUDY

• The patient's symptoms (jaundice, right upper abdominal pain, fever, and malaise) and eventual progression to altered mental status and vomiting suggest a fungal infection, likely cryptococcal meningitis
• The patient's low healthcare literacy and potential pre-existing liver condition may have contributed to the delayed diagnosis and poor outcome