Blood culture (LAB462), Disseminated Malassezia spp

When fungemia due to Malassezia is suspected, include an order comment to include lipid-supplemented growth medium.

Clinical Background
  • Malassezia spp. are lipophilic yeasts found on skin that are considered emerging fungal pathogens due to their ability to cause systemic infections. Severe Malassezia infections may occur due to catheter-associated sepsis in neonates or adults receiving prolonged intravenous lipids via total parenteral nutrition (TPN). Lipid supplementation provided by TPN allows for the proliferation of Malassezia spp. in blood.
  • The incidence of Malassezia fungemia is likely underestimated due to the difficulty with culturing lipophilic Malassezia spp. Most Malassezia spp., including M. furfur, don’t grow in culture unless the growth medium is supplemented with long-chain fatty acids. Thus, while most clinically relevant yeasts, such as Candida and Cryptococcus, are readily recovered by routine blood cultures, a mold blood culture that is supplemented with lipids is needed when fungemia due to Malassezia ssp. is suspected. When Malassezia ssp. is suspected, an order comment of “include lipid-supplemented growth medium” should be included to notify the Microbiology laboratory to ensure the proper growth media is used.
Common Pitfalls
  • Bloodstream infections caused by Malassezia spp. are likely underestimated because of their inability to grow in routine blood culture media.
  • Lipophilic Malassezia spp. don’t grow in culture unless the culture medium is supplemented with lipids, which is not routine laboratory practice.
Key Takeaways
  • Unlike other yeasts, such as Candida and Cryptococcus, a mold blood culture should be ordered for suspected Malassezia fungemia. Mold blood cultures, and not routine blood cultures, may be supplemented with lipids to allow for Malassezia growth.
  • If Malassezia spp. is a suspected pathogen, this should be stated in a comment included with the culture order so that lipid-supplemented culture media is utilized.
References
  1. Rhimi W, Theelen B, Boekhout T, Otranto D, Cafarchia C.2020. Malassezia spp. Yeasts of Emerging Concern in Fungemia. Frontiers in Cellular and Infection Microbiology 10.
  2. Gaitanis G, Magiatis P, Hantschke M, Bassukas ID, Velegraki A.2012. The Malassezia Genus in Skin and Systemic Diseases. Clinical Microbiology Reviews 25.

Written By: Michaela Eickhoff, PhD

Reviewed By: Rebekah Dumm, PhD

Last Edited: 2023-08-29

Last Reviewed: 2023-08-29