Species Identification and In Vitro Antifungal Susceptibility of Paecilomyces/Purpureocillium Species Isolated from Clinical Respiratory Samples: A Multicenter Study.

Paecilomyces spp. are emerging fungal pathogens, where Paecilomyceslilacinus and Paecilomyces variotii are the most reported species. Taxonomic and phylogenetic revisions in this genus have shown that P. variotii represents a species complex, whereas P. lilacinus is related to another genus called Purpureocillium. The aims of this study were to identify clinical isolates of Paecilomyces spp. at the species level, and to determine their antifungal susceptibility profiles. 70 clinical Paecilomyces spp. isolates were identified by MALDI-TOF Mass Spectrometry (MS) and by multilocus rDNA genes sequencing including ITS and the D1/D2 genes. Among the 70 Paecilomyces spp. isolates, 28 were identified as P. lilacinum, 26 as P. variotii stricto sensu, and 16 as P. maximus. For antifungal susceptibility testing, Minimal Inhibitory Concentrations (MICs) or Minimal Effective Concentrations (MECs) were determined for 8 antifungals. All P. lilacinum isolates had high MICs and MECs of amphotericin B and echinocandins, respectively, unlike P. variotii and P. maximus. For azole drugs, MICs were molecule- and species- dependent. The differences in in vitro susceptibility to antifungals underline the importance of accurate species identification. The MALDI-TOF MS can be a good alternative in routine laboratory to ensure fast identification of Paecilomyces spp. and P. lilacinum.

Successful treatment of Trichosporon asahii fungemia with isavuconazole in a patient with hematologic malignancies.

Trichosporon spp. are yeast-like microorganisms responsible for skin, urinary, pulmonary, or bloodstream infections. Due to intrinsic resistance to echinocandins, poor susceptibility to polyenes, and preferred occurrence in immunocompromised patients, such infections are often of poor prognosis. Yet no consensual therapeutic guidelines are presently available. Several clinical cases of Trichosporon infections have been successfully treated with azole therapy, including voriconazole which appeared frequently effective against Trichosporon both in vitro and in vivo. However, the low efficacy associated with some Trichosporon genotypes, complex pharmacokinetics, and the side effects of voriconazole represent limitations for its use and has prompted a search for other therapeutic options. Here, we report a case of T. asahii fungemia in a patient with B-cell acute lymphoblastic leukemia which was successfully treated with isavuconazole consecutive to stopping voriconazole therapy due to severe side effects. This observation suggests that isavuconazole with a similar spectrum to voriconazole, fewer pharmacology interactions, and side effects may be considered as a valuable therapeutic option against Trichosporon infections.