Fusarium

Microbiology

• Macroscopic: colonies grow rapidly with wooly texture (sometimes mucoid), and white, yellow, pink, purple, or pale brown surface and pale, red, violet, brown, or blue reverse.
• Microscopic: septate hyaline hyphae. Microconidia are unicellular (sometimes bicellular) and hyaline, ovoid to ellipsoid, in chains or singly from denticles. Macroconidia are curved and multicellular, with a foot cell at the base. Chlamydospores may be present.
  • The macroconidia are the typical finding used to identify Fusarium spp.

Species that cause disease

• F. solani: most common overall, and a common cause of keratitis
• F. oxysporum: second-most common
• F. verticillioides: third-most common
• F. moniliforme
• F. proliferatum
• F. chlamydosporum
• F. anthophilum
• F. dimerum
• F. sacchari

Epidemiology

• Ubiquitous, common in soil and organic debris, and a common cause of disease in plants.
• In humans, infection is rare and generally occurs after penetrating trauma.
• Disseminated and CNS disease is more common in immunocompromised hosts, including prolonged neutropenia.

Clinical Manifestations

• Superficial
  • Keratitis and endophthalmitis: big outbreak associated with contact lens solution back in the day
  • Onychomycosis
  • Skin and musculoskeletal infections (including mycetoma)
• Locally invasive
  • Pneumonia
  • Peritonitis associated with peritoneal dialysis
  • Brain abscess
• Disseminated infection
  • Fungemia: can be detected in blood culture
  • Disseminated infection

Management

• Remove indwelling lines
• Treat underlying immunocompromise, if possible
• Amphotericin B (high dose) is the antifungal of choice, although vori and posa have also been used