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

Abstract

Background: 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. Objectives: To determine the epidemiology and susceptibility of Magnusiomyces isolates from bloodstream infections (BSI) isolated in Germany and Austria from 2001-2020. Methods: In seven institutions a total of 34 Magnusiomyces BSI were identified. Identification was done by ITS sequencing and MALDI-TOF MS. Antifungal susceptibility was determined by EUCAST broth microdilution and gradient tests. Results: Of the 34 isolates, M. clavatus was more common (N=24) compared to M. capitatus (N=10). BSI by Magnusiomyces spp. were more common in men (62%) and mostly occurred in patients with haemato-oncological malignancies (79%). The highest in vitro antifungal activity against M. clavatus / M. capitatus was observed for voriconazole (MIC 50 0.03/0.125 mg/L), followed by posaconazole (MIC 50 0.125/0.25 mg/L). M. clavatus isolates showed overall lower MICs compared to M. capitatus . With the exception of amphotericin B, low essential agreement between gradient test and microdilution was recorded for all antifungals (0-70%). Both species showed distinct morphologic traits on ChromAgar Orientation and Columbia blood agar, which can be used for differentiation if no MALDI-TOF or molecular identification is available. 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.

Case report: A Saprochaete clavata (Magnusiomyces clavatus) severe infection effectively treated with granulocyte transfusion in a young patient with myeloid sarcoma

“…In this report, S. clavata was found to be responsible for disseminated and life-threatening infection in a young patient with AML, during a profound neutropenic phase after the second course of the FLAI CHT regimen. In line with available literature ( 10 , 12 , 22 , 23 ), the susceptibility test has shown a high MIC for echinocandins and fluconazole and low for amphotericin B, itraconazole, posaconazole, and voriconazole ( 10 , 12 , 23 – 25 ). Not enough clinical data are available to assess the optimal treatment for this infection: a 2014 guideline for treatment of S. clavata infection recommended any formulation of amphotericin B ± other antifungals as the preferred approach ( 12 , 22 ).…”

Disseminated fungal disease caused by Magnusiomyces clavatus in a pediatric cancer patient: Case report and review of the literature

“…1,2 Closely related to, and potentially misidentified as, Magnusiomyces capitatus, its incidence has likely been underestimated prior to use of advanced identification techniques. 3,4 Detailed ecological studies are scarce but other Magnusiomyces spp are ubiquitous in environmental sources such as water, soil, and plants. 5 In one study of hospitalized adults, asymptomatic colonization with Magnusiomyces spp was relatively common, especially in the respiratory tract, and associated with invasive infection in immunocompromised individuals.…”

Candidiasis and Other Emerging Yeasts

“…Hospital-associated outbreaks have also been reported with the largest involving 39 cases in France in 2013 [ 71 ]. Thirty-four cases of BSI have been reported from Germany and Austria over 20 years, though various sporadic cases have also been reported [ 72 ]. Infection is primarily seen in immunocompromised individuals especially those with acute leukemia.…”

“…[ 69 ]. The natural reservoirs and virulence factors of these yeasts are not known, and the whole genome sequencing of the agent suggest its recent emergence [ 72 ].…”