Bloodstream Infections Caused by Magnusiomyces capitatus and Magnusiomyces clavatus : Epidemiological, Clinical, and Microbiological Features of Two Emerging Yeast Species

Janina Noster (1) , Martin Koeppel (2) , Marie Desnos-Olivier (3, 4) , Maria Aigner (5) , Oliver Bader (6) , Karl Dichtl (2) , Stephan Göttig (7) , Andrea Haas (2) , Oliver Kurzai (8, 9) , Arthur Pranada (10) , Yvonne Stelzer (1) , Grit Walther (9) , Axel Hamprecht (1, 11, 12)

1 OFFIS - Carl Von Ossietzky Universität Oldenburg = Carl von Ossietzky University of Oldenburg
2 LMU - Ludwig Maximilian University [Munich] = Ludwig Maximilians Universität München
3 Mycologie moléculaire - Molecular Mycology
4 CNRMA - Centre National de Référence Mycoses Invasives et Antifongiques - National Reference Center Invasive Mycoses & Antifungals
5 IMU - Innsbruck Medical University = Medizinische Universität Innsbruck
6 UMG - University Medical Center Göttingen
7 Goethe-Universität Frankfurt am Main
8 JMU - Julius-Maximilians-Universität Würzburg
9 Leibniz Institute for Natural Product Research and Infection Biology (Hans Knoell Institute)
10 MVZ Dr. Eberhard & Partner Dortmund
11 DZIF - German Centre for Infection Research
12 Universität zu Köln = University of Cologne

Magnusiomyces clavatus and Magnusiomyces capitatus are emerging yeasts with intrinsic resistance to many commonly used antifungal agents. Identification is difficult, and determination of susceptibility patterns with commercial and reference methods is equally challenging. For this reason, few data on invasive infections by Magnusiomyces spp. are available. Our objectives were to determine the epidemiology and susceptibility of Magnusiomyces isolates from bloodstream infections (BSI) isolated in Germany and Austria from 2001 to 2020. In seven institutions, a total of 34 Magnusiomyces BSI were identified. Identification was done by internal transcribed spacer (ITS) sequencing and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Antifungal susceptibility was determined by EUCAST broth microdilution and gradient tests. Of the 34 isolates, M. clavatus was more common (n = 24) than M. capitatus (n = 10). BSI by Magnusiomyces spp. were more common in men (62%) and mostly occurred in patients with hemato-oncological malignancies (79%). The highest in vitro antifungal activity against M. clavatus/M. capitatus was observed for voriconazole (MIC50, 0.03/0.125 mg/L), followed by posaconazole (MIC50, 0.125/0.25 mg/L). M. clavatus isolates showed overall lower MICs than M. capitatus. With the exception of amphotericin B, low essential agreement between gradient test and microdilution was recorded for all antifungals (0 to 70%). Both species showed distinct morphologic traits on ChromAgar Orientation medium and Columbia blood agar, which can be used for differentiation if no MALDI-TOF MS or molecular identification is available. In conclusion, most BSI were caused by M. clavatus. The lowest MICs were recorded for voriconazole. Gradient tests demonstrated unacceptably low agreement and should preferably not be used for susceptibility testing of Magnusiomyces spp.

Mots clés: Saprochaete clavata; Saprochaete capitata; Magnusiomyces capitatus; Magnusiomyces clavatus; Geotrichum; bloodstream infection; MIC

Domaines: Sciences du Vivant [q-bio]

Janina Noster, Martin Koeppel, Marie Desnos-Olivier, Maria Aigner, Oliver Bader, et al.. Bloodstream Infections Caused by Magnusiomyces capitatus and Magnusiomyces clavatus : Epidemiological, Clinical, and Microbiological Features of Two Emerging Yeast Species. Antimicrobial Agents and Chemotherapy, 2022, 66 (2), pp.e01834-21. ⟨10.1128/AAC.01834-21⟩. ⟨pasteur-04100140⟩