Scedo… what?

Labs and Lytes 010

Author: Chris Nickson
Reviewer: Steve McGloughlin

A 21 year-old male was involved in a house fire and sustained 50% body surface area burns affecting his head, torso and all limbs. During his first week in ICU he developed an ongoing fever, elevated inflammatory markers and a persistent noradrenaline requirement. His septic screen yielded polymicrobial growth from multiple wound sites and on blood culture.

Q1. What are the risk factors for fungal infection in ICU?

Risk factors include:

  • Immunosuppression – whether due to drugs or disease, such as HIV, transplant patients or – in this case – severe burns
  • Parentral nutrition (especially TPN)
  • Abdominal surgery and/or GI tract perforation
  • Broad spectrum antibiotic therapy
  • Diabetes mellitus
  • Neutropaenia
  • Prosthetic devices (e.g. longterm indwelling vascular access lines, prosthetic heart valves)

The microbiology registrar phones you.  A filamentous mold is growing from the blood and wound cultures. Full identification is not yet available.

Q2. What is the significance of this finding?

Filamentous molds include pathogenic fungi such as Aspergillus, Zygomycoses such as Mucor, and Scedosporium species.

These organisms can cause life-threatening infections.

Subsequently, the organism is confirmed as Scedosporium prolificans.

 

Here are some key things to know about this Scedosporium prolificans:

  • It can cause a variety of infections: soft tissue infections, septic arthritis, osteomyelitis, ophthalmic infections, sinusitis, pneumonia, meningitis, brain abscesses, endocarditis and disseminated infection
  • it is increasingly recognised in severely ill and immunocompromised patients, although Aspergillus remains the most common cause of invasive fungal infection
  • Scedosporium infection also occurs in immunocompetent patients, with transcutaneous inoculation via traumatic wounds being a common precipitant

Q3. How should the organism identified in Q3 be treated?

Scedoporum prolificans is highly resistant – importantly it may not respond to therapies often used for other filamentous fungi such as Aspergillus. It has high minimum inhibitory concentrations (MICs) to agents such as:

  • Amphotericin B
  • Fluconazole
  • Ketoconazole
  • Voriconazole
  • Miconazole

Optimal therapy for this organism is uncertain, and based largely on in vitro data. Typical agents used are voriconazole (despite the apparent in vitro resistance) and/or terbenafine. Prolonged treatment is often needed.

In addition to antimicrobials remember to correct any reversible factors that perpetuate ongoing fungal infection. This includes removing protheses (e.g. lines) if possible and optimising the patient’s immune function when appropriate (e.g. nutrition, stop immunosuppressants, etc).

Take advice from the microbiologists on this one!

References and Links

  • Cooley L, Spelman D, Thursky K, Slavin M. Infection with Scedosporium apiospermum and S. prolificans, Australia. Emerg Infect Dis. 2007 Aug;13(8):1170-7. PubMed PMID: 17953087; PubMed Central PMCID: PMC2828065.
  • Cortez KJ, Roilides E, Quiroz-Telles F, Meletiadis J, Antachopoulos C, Knudsen T, Buchanan W, Milanovich J, Sutton DA, Fothergill A, Rinaldi MG, Shea YR, Zaoutis T, Kottilil S, Walsh TJ. Infections caused by Scedosporium spp. Clin Microbiol Rev. 2008 Jan;21(1):157-97. doi: 10.1128/CMR.00039-07. Review. PubMed PMID: 18202441; PubMed Central PMCID: PMC2223844.
  • Katz T, Wasiak J, Cleland H, Padiglione A. Incidence of non-candidal fungal infections in severe burn injury: An Australian perspective. Burns. 2013 Dec 28. pii: S0305-4179(13)00405-1. doi: 10.1016/j.burns.2013.11.025. [Epub ahead of print] PubMed PMID: 24380706.

All case-based scenarios on INTENSIVE are fictional. They may include realistic non-identifiable clinical data and are derived from learning points taken from clinical practice. Clinical details are not those of any particular person; they are created to add educational value to the scenarios.

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