Some species in the polyphyletic fungal genus Acremonium are important opportunist pathogens. Determining the actual spectrum of species and their incidence in the clinical setting, however, has long been hampered because of the difficulties encountered in phenotypic species-level identification. The goal of this study was to re-identify a large number of clinical isolates morphologically and to confirm the identifications by comparing sequences of the internal transcribed spacer region of the rRNA gene of these isolates to those of type or reference strains of well-known Acremonium species. Of the 119 isolates referred to a United States reference laboratory under the name Acremonium, only 75 were identified morphologically as belonging to that genus. The remainder (44 isolates) were identified as belonging to other morphologically similar genera. The Acremonium clinical isolates were related to species of Hypocreales, Sordariales, and of an incertae sedis family of ascomycetes, Plectosphaerellaceae. A total of 50 of the 75 Acremonium isolates (67%) could be identified by molecular means, the prevalent species being Acremonium kiliense (15 isolates), A. sclerotigenum-A. egyptiacum (11 isolates), A. implicatum (7 isolates), A. persicinum (7 isolates), and A. atrogriseum (4 isolates). One of the most interesting findings of our study was that we identified several species among this large collection of clinical isolates that had not previously been reported from human infections, and we failed to confirm other Acremonium species, such as A. potronii, A. recifei, and A. strictum, that had been considered significant. The most common anatomic sites for Acremonium isolates were the respiratory tract (41.3%), nails (10.7%), and the eye (9.3%). Antifungal susceptibility testing demonstrated high MICs for all agents tested, except for terbinafine. Since numerous isolates could not be identified, we concluded that the list of opportunistic Acremonium species is far from be complete and that a considerable number of additional species will be discovered.

In molecular studies involving numerous clinical isolates of the genera Acremonium, Phialemonium and Lecytophora some of them could not be identified. To clarify the phylogenetic relationships among these fungi and other related taxa, we performed a polyphasic study based on a detailed morphological study and on the analysis of sequences of four loci: the internal transcribed spacer regions, the D1/D2 domains of the 28S rRNA, actin and β-tubulin genes. The combination of the resulting data let us propose the new genus Phialemoniopsis to accommodate the opportunistic fungi Phialemonium curvatum and Sarcopodium oculorum and two new species, Phialemoniopsis cornearis and Phialemoniopsis pluriloculosa. The taxonomy of Phialemoniopsis has not been completely resolved, however, remaining incertae sedis within the Sordariomycetes. In addition, the new species Lecythophora luteorubra, Lecythophora cateniformis and Phialemonium globosum are described and the species Acremonium atrogriseum and Taifanglania inflata are transferred to the genus Phialemonium. Lecythophora and Phialemonium are currently monophyletic genera of the families Coniochaetaceae (Coniochaetales) and Cephalothecaceae (Sordariales) respectively, according to our results. Tables summarizing key morphological features to distinguish the current species of Lecythophora, Phialemonium and Phialemoniopsis are provided.

Purpureocillium is a genus recently proposed to accommodate Paecilomyces lilacinus, a well studied species that has biotechnological properties and an ability to cause human infections. Since contradictory data have been reported on the intraspecific genetic variability of P. lilacinum, we have carried out a polyphasic study of a set of clinical and environmental isolates of this species. Detailed morphological examination and sequence analysis of four different loci, including the ribosomal internal transcribed spacer, the domains D1 and D2 of the 28S rDNA, EF-1a and the largest subunit of RNA polymerase II (rpb1), showed that P. lilacinum formed a well supported phylogenetic clade with low intraspecific variability. The new species Purpureocillium lavendulum, which has vinaceous colonies similar to those of P. lilacinum, is proposed. It is characterized by the lack of growth at 35 C, the production of a yellow diffusible pigment and by subglobose or limoniform conidia.