Scedosporium

Scedosporium is a pathogenic fungus that causes a wide variety of infections. Scedosporium species are commonly found in rural soils, polluted waters, composts, and from manure of cattle and fowl. Human activity, including intense fertilization and hydrocarbon waste, supports growing of Scedosporium species in the environment. Some of the highest concentrations of Scedosporium species can be found in industrial sites, near gas stations, in urban parks, and within agricultural areas.3

ScedosporiumApical part of hyphae of the Scedosporium apiospermum anamorph producing conidia. Source: Mycobiology. 2014 Dec; 42(4): 397–400 doi: 10.5941/MYCO.2014.42.4.397

Infections are caused by two species: S. apiospermum and S. prolificans (S. inflatum). Serious Scedosporium infections have increased in the past few years among patients with hematologic cancers, AIDS and cystic fibrosis. In otherwise healthy individuals, infection with Scedosporium may result from a local trauma, inhalation of spores, ingestion of contaminated food, and with no apparent source. Symptoms include keratitis, otitis, sinusitis, central nervous system infections, joint and soft tissue infections, and pneumonia after near drowning.1 Pathological features in tissue sections of both Scedosporium species can be easily confused with with those of Aspergillus and Fusarium and have shown resistance to a wide variety of antifungal drugs, such as amphotericin B, miconazole and ketoconazole.2,4 Voriconazole (brand name Vfend, Pfizer) is the drug of choice for Scedosporium infections. Ultimate recovery from all mold infections is dependent on resolution of neutropenia5 (abnormally low number of neutrophils that serve as the primary defense against infections).

S. prolificans is an imperfect fungus, but, unlike S. apiospermum, its sexual state (teleomorph) is still unknown. In infected tissues S. prolificans is indistinguishable from S. apiospermum. S. prolificans may cause phaeohyphomycosis.

Among North American lung transplant recipients, Scedosporium species are the second most common cause of filamentous fungal infection, following only aspergillosis. Patients who are colonized with Scedosporium before transplant can develop infections with the same strain after transplant.

References

  1. Clinical Mycology. Elias J. Anaissie, Michael R. McGinnis, Michael A. Pfaller
  2. Opportunistic Infections: Treatment and Prophylaxis. Vassil St. Georgiev
  3. Infectious Disease Challenges in Solid Organ Transplant Recipients, an Issue of Infectious Disease Clinics. Joseph G Timpone, Jr., Princy N. Kumar
  4. Textbook of Diagnostic Microbiology. Elmer W. Koneman
  5. Internal Medical Care of Cancer Patients. Yeung

 

 

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