USMLE

Paracoccidioides

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Fungi
  1. Histoplasma
  2. Blastomyces
  3. Coccidioides
  4. Paracoccidioides
  5. Tinea (Dermatophytes)
  6. Malassezia
  7. Candida albicans
  8. Aspergillis fumigatus
  9. Cryptococcus neoformans
  10. Mucor and Rhizopus
  11. Pneumocystis jirovecii
  12. Sporothrix schenckii

Summary

Paracoccidioides is a fungi endemic to Latin America that can cause a disease known as Paracoccidiodomycosis. It is a dimorphic fungi, meaning that it exists in two forms. Outside of the body, the fungus exists as a mold, and the spores it produces can be inhaled and brought into the body. Once inside the human body, warmer temperatures trigger its conversion into its other form: a yeast form.

Paracoccidioides is endemic to Latin America, and infection is much more prevalent in males than females. Some clinical presentations of paracoccidioidomycosis include pneumonia, skin lesions, mouth ulcers, and anemia. Histopathology will reveal fungal yeast cells with a “captain’s wheel” appearance, as well as the formation of granulomas around the fungi. Finally, itraconazole is prescribed for mild or moderate infections, while more severe cases require treatment with amphotericin B.

Key Points

  • Paracoccidioides spp.
    • Includes P. brasiliensis, P. lutzii
    • Characteristics
      • Dimorphic yeasts
        • Mold in soil
        • Yeast in body
    • Transmission
      • Endemic to Latin America
      • Males affected > females
        • 13:1 ratio of men to women affected
        • Estradiol thought to be protective
      • Transmitted by inhalation of spores
      • Cannot be transmitted from person to person (unlike TB)
    • Presentation
      • Causes Paracoccidioidomycosis
        • Pneumonia
          • Acutely presents with fever, cough
          • May develop into chronic inflammatory lung disease
            • Pulmonary infiltrates and upper respiratory mucosal lesions
        • Anemia
          • Seen in nearly 90% of acute infections
        • Mucosal ulcers
          • More common in chronic infections
          • Mouth is affected, with painful hemorrhagic ulcers
        • Skin lesions
          • More common in chronic infections
          • Verrucous (vegetative) lesions are seen
        • CNS, liver, lymph node, and GI involvement are also seen
    • Diagnosis
      • Histopathology
        • Large round yeast surrounded with budding daughter cells, in a “captain’s wheel” formation
          • Much larger than RBC
        • Forms granulomas around yeast
      • Serological testing for antifungal antibodies is used for diagnosis
    • Treatment
      • Itraconazole for mild or moderate infection
        • Other azoles or TMP-SMX are second-line
      • Amphotericin B for severe infection or CNS involvement