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

Abstract

Paecilomyces spp. are emerging fungal pathogens, where Paecilomyces lilacinus 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.

Case Report: Cutaneous Mycosis Caused by Purpureocillium lilacinum

“…The management of P. lilacinum infection is fraught with challenges manifested predominantly in its intrinsic resistance to amphotericin B. 5 Monpierre et al 6 extracted P. lilacinum from cultures of respiratory specimens of patients and tested their sensitivity to common antifungal agents in vitro. The final results showed that all azoles were active on P. lilacinum.…”

“…7,8 Voriconazole and posaconazole are novel azoles that have been effective against this fungal species. 6 Of note, voriconazole-resistant strains have already been found. 9,10 Thus, fungal identification and susceptibility testing are essential.…”

Invasive aspergillosis in liver transplant recipients

“…Matrix-assisted laser desorption ionization-time of flight mass spectrometry is a tool that has shown its value for the identification of filamentous fungi where the concordance with molecular identification by sequencing reaches more than 98%. 136 The importance of species identification is major due to the differences in sensitivity to antifungal agents between species. 137 In addition, in the case of Aspergillus isolation, the determination of MICs for azole antifungals is relevant due to the increase in strains carrying azole resistance mutations.…”

Non-Aspergillus Hyaline Molds: A Host-Based Perspective of Emerging Pathogenic Fungi Causing Sinopulmonary Diseases

“…Paecilomyces variotii is resistant in vitro to voriconazole and isavuconazole, while remaining susceptible to amphotericin B, echinocandins, posaconazole, and itraconazole [ 88 , 191 , 192 , 193 ]. Case reports of breakthrough P. variotii disease in patients receiving voriconazole treatment or prophylaxis support the limited role for this agent [ 107 ].…”

“…P. lilacinum is generally susceptible to the triazoles with the lowest observed MICs for voriconazole and posaconazole. Activity of the echinocandins is variable [ 89 , 193 ]. Clinical studies also suggest good outcomes when voriconazole is used for invasive P. lilacinum disease, and one study demonstrated improved survival in patients treated with voriconazole rather than amphotericin B [ 89 , 194 ].…”