Raman Study of Pathogenic Candida auris: Imaging Metabolic Machineries in Reaction to Antifungal Drugs

Giuseppe Pezzotti; Miyuki Kobara; Tamaki Nakaya; Hayata Imamura; Tenma Asai; Nao Miyamoto; Tetsuya Adachi; Toshiro Yamamoto; Narisato Kanamura; Eriko Ohgitani; Elia Marin; Wenliang Zhu; Ichiro Nishimura; Osam Mazda; Tetsuo Nakata; Koichi Makimura

doi:10.3389/fmicb.2022.896359

Raman Study of Pathogenic Candida auris: Imaging Metabolic Machineries in Reaction to Antifungal Drugs

Front Microbiol. 2022 May 25:13:896359. doi: 10.3389/fmicb.2022.896359. eCollection 2022.

Authors

Giuseppe Pezzotti^{1

2

3

4

5}, Miyuki Kobara⁶, Tamaki Nakaya¹, Hayata Imamura¹, Tenma Asai¹, Nao Miyamoto⁴, Tetsuya Adachi⁴, Toshiro Yamamoto⁴, Narisato Kanamura⁴, Eriko Ohgitani², Elia Marin^{1

4}, Wenliang Zhu¹, Ichiro Nishimura⁷, Osam Mazda², Tetsuo Nakata⁶, Koichi Makimura⁸

Affiliations

¹ Ceramic Physics Laboratory, Kyoto Institute of Technology, Kyoto, Japan.
² Department of Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
³ Department of Orthopedic Surgery, Tokyo Medical University, Tokyo, Japan.
⁴ Department of Dental Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
⁵ The Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka, Japan.
⁶ Division of Pathological Science, Department of Clinical Pharmacology, Kyoto Pharmaceutical University, Kyoto, Japan.
⁷ Division of Advanced Prosthodontics, The Jane and Jerry Weintraub Center for Reconstructive Biotechnology, UCLA School of Dentistry, Los Angeles, CA, United States.
⁸ Medical Mycology, Graduate School of Medicine, Teikyo University, Tokyo, Japan.

Abstract

The multidrug-resistant Candida auris often defies treatments and presently represents a worldwide public health threat. Currently, the ergosterol-targeting Amphotericin B (AmB) and the DNA/RNA-synthesis inhibitor 5-flucytosine (5-FC) are the two main drugs available for first-line defense against life-threatening Candida auris infections. However, important aspects of their mechanisms of action require further clarification, especially regarding metabolic reactions of yeast cells. Here, we applied Raman spectroscopy empowered with specifically tailored machine-learning algorithms to monitor and to image in situ the susceptibility of two Candida auris clades to different antifungal drugs (LSEM 0643 or JCM15448T, belonging to the East Asian Clade II; and, LSEM 3673 belonging to the South African Clade III). Raman characterizations provided new details on the mechanisms of action against Candida auris Clades II and III, while also unfolding differences in their metabolic reactions to different drugs. AmB treatment induced biofilm formation in both clades, but the formed biofilms showed different structures: a dense and continuous biofilm structure in Clade II, and an extra-cellular matrix with a "fluffy" and discontinuous structure in Clade III. Treatment with 5-FC caused no biofilm formation but yeast-to-hyphal or pseudo-hyphal morphogenesis in both clades. Clade III showed a superior capacity in reducing membrane permeability to the drug through chemically tailoring chitin structure with a high degree of acetylation and fatty acids networks with significantly elongated chains. This study shows the suitability of the in situ Raman method in characterizing susceptibility and stress response of different C. auris clades to antifungal drugs, thus opening a path to identifying novel clinical solutions counteracting the spread of these alarming pathogens.

Keywords: Candida auris; Raman; antifungal; fungal infection; metabolism.