1723. Human Serum Albumin Regulates the Growth of Candida auris in vitro

BACKGROUND: Candida auris is commonly detected in human ear secretions. However, C. auris occasionally causes bloodstream infections even in immunocompetent patients resulting in poor prognosis. It was speculated that C. auris growth within the blood might be regulated by proteins in the bloodstream. Thus, in this study, the potential role of blood proteins in the regulation of C. auris growth was investigated. METHODS: Five Candida species (C. albicans, C. auris, C. glabrata, C. parapsilosis, and C. tropicalis) were incubated overnight. Colony suspensions for each species were prepared and adjusted to OD 1.0 at absorbance 0.1. Then, human serum albumin (HSA) and bovine serum albumin (BSA) were diluted (2.5 g/dL–0.002 g/dL) and mixed with the suspensions. Mixed samples were adjusted to 100 μL and incubated on MHA plates at 35°C for 2 days. Then, 50 μL of the combined sample was extracted and streaked onto Yeast extract-Peptone-Dextrose (YPD) agar. The remaining 50 μL sample was analyzed using an XTT assay. Further testing was then conducted on the effects of a specific blood protein albumin on Candida. Thereby, C. albicans and C. auris were cultured following the procedure above and stained with Annexin V and PI. RESULTS: The growth of C. auris mixed with a high albumin concentration (2.5~0.15 g/dL) was regulated compared with that of other Candida species (P < 0.01) (Figures 1 and 2); however, the growth of C. auris mixed with a lower albumin concentration was similar to that of other species. The wash-out study showed that C. auris growth and survival in the high albumin concentration was not different than that of other species. CONCLUSION: HSA and BSA regulated C. auris growth which led to increased necrosis of C. auris. Conversely, growth of the other Candida species was not regulated. Therefore, albumin might be involved in the growth and necrosis of C. auris. As the highest concentration at which albumin regulated C. auris growth was similar to that found in human serum, it is possible that serum albumin might help prevent C. auris from entering the bloodstream via the ear or skin. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.