Kodamaea ohmeri: An emergent yeast from a One Health perspective

Abstract

Kodamaea ohmeri is an emerging and opportunistic yeast associated with a high mortality rate in humans. As it is commonly found in the environment, it is possible that environmental conditions and agricultural practices contribute to the adaptation of this yeast and the selection of antifungal resistance. During a multicentric study in Brazil, conducted under a One Health perspective, 14 isolates of K. ohmeri were identified from different sources: three from blood cultures, three from animals (swine and poultry), and eight from animal environments (swine and poultry). Yeasts were isolated using CHROmagar® Candida medium and identified by MALDI-TOF MS and ITS rDNA barcoding. Minimum inhibitory concentration (MIC) was determined using the broth microdilution method for clinical (azoles, echinocandins, pyrimidine analogs, and polyenes), and environmental antifungals (tebuconazole, pyraclostrobin, carbendazim, and mancozeb), and hospital disinfectants (quaternary ammonium compounds). Of note, color variations of K. ohmeri were noted on CHROmagar® depending on the incubation time, which is likely to complicate its identification. Following polyphasic identification and taxonomic confirmation, all isolates demonstrated low MIC values for clinical antifungals, disinfectants, and tebuconazole. However, all isolates were able to grow in the presence of carbendazim, mancozeb, and pyraclostrobin. Together, these findings highlight the risks associated with the use of environmental azoles, such as tebuconazole, as they may impact non-target fungi of medical importance, but other fungicides do not present the same risk. This is the first study to demonstrate that K. ohmeri, an important emerging yeast in human medicine, can be isolated from various sources, including patients. Although the isolates exhibited low MIC values for clinical antifungals, it is crucial to monitor changes in sensitivity patterns over time in emerging microorganisms to prevent the development of multidrug resistance, which may originate in the environment.

Keywords: Agrochemicals; Cross-resistance; Hospital disinfectants; Yeasts.

Graphical abstract

Fig. 1

Evolutionary relationships of 24 taxa. ITS rDNA phylogenetic tree of the 14 Kodamaea ohmeri isolates using Maximum Parsimony method. The bootstrap consensus tree inferred from 1000 replicates is taken to represent the evolutionary history of the taxa analyzed. Branches corresponding to partitions reproduced in less than 50 % bootstrap replicates are collapsed.

Fig. 2

Variation of color and aspect of 14 Kodamaea ohmeri isolates on CHROmagar® Candida over time. Overall, after 24 h of incubation, the colonies display a pink or lilac color, with a blue background that may or may not be visible. After 48 h, the color gradually shifts to blue, and after 72 h or more of incubation, the colonies of K. ohmeri become green.