Ecology and physiology of the emerging opportunistic fungi Pseudallescheria boydii and Scedosporium prolificans

Abstract

Summary. Nutritionally physiological patterns of Pseudallescheria boydii (Microascaceae) and the related species Scedosporium prolificans were established. Differences between the two species were found in assimilation of sucrose, ribitol, xylitol and L‐arabinitol. In contrast, no physiological distinction could be made between the three intraspecific variants of P. boydii which have been recognized on the basis of nDNA/DNA homology data and of morphological and clinical differences. Some potential virulence factors were studied in the fungi mentioned above and in some related anamorphs. All species were capable of anaerobic growth, but differed in their temperature relations. Zusammenfassung. Assimilations‐Muster von Pseudallescheria boydii (Microascaceae) und der verwandten Art Scedosporium prolificans wurden untersucht. Dabei wurden Art‐Unterschiede in der Assimilation von Saccharose, Ribitol, Xylitol und L‐Arabinitol festgestellt. Im Gegensatz dazu wurden keine physiologischen Unterschiede zwischen den drei Varianten innerhalb der Art P. boydii nachgewiesen. Damit lassen sich die bisher verwendeten Merkmalsunterschiede, bzw. nDNA/DNA Homologie‐Werte sowie morphologische und klinische Characteristika, nicht bestätigen. Einige mögliche Virulenz‐Faktoren bei den oben beschriebenen sowie auch bei einigen verwandten Arten, wurden untersucht. Alle Arten erwiesen sich im gleichen Maß zum anaeroben Wachstum befähigt, unterscheiden sich aber in ihrem Temperaturverhalten.

Infections Caused byScedosporiumspp

“…There are only uncommon reports of isolation of the fungus from the intestinal tracts of amphibians (http://www .scedosporium-ecmm.com/index.htm). By comparison, S. prolificans has been isolated from soil and animals (31,482), such as cats, and horses, but it seems that its ecosystem may be more restricted to soil and potted plants (93,426). While S. apiospermum has a more uniform geographic worldwide distribution, S. prolificans seems to be restricted to the northern part of the Iberic peninsula and Australia (35,406), as well as California and the southern United States (204).…”

“…Species are proteolytic and amylolytic. Glucose but not lactose or maltose is assimilated (93). However, studies of carbohydrate nutrition and sporulation of P. boydii/S.…”

Molecular Phylogeny and Proposal of Two New Species of the Emerging Pathogenic FungusSaksenaea

“…The medium with the nitrogen sources was dispensed into the wells in 150-l volumes with a multichannel pipette, and each well was inoculated with 50 l of the conidial suspension. The microplates were incubated at 37°C in darkness for 48 to 72 h. We also evaluated the growth of the strains on NaCl (at 2%, 5%, 7%, and 10%), 2% MgCl 2 , and 0.1% cycloheximide (14,49). All tests were performed in duplicate.…”

Osteomyelitis and Discospondylitis due to Scedosporium Apiospermum in a Dog

“…Its growth is promoted by manureenriched or polluted environments. 6,16 Systemic diseases caused by S. apiospermum have been referred to as allescheriasis, graphitosis, monosporiosis, petriellidiosis, pseudallescheria, pseudallescheriasis, or scedosporiosis. 10 This organism is now recognized as a potent and emerging pathogen of severe infection in immunosuppressed human patients.…”

“…"content-markup(./author-grp [1]/aff|./author-grp [1]/dept-list)> Scedosporium apiospermum, 1 of 2 anamorphs of Pseudallescheria boydii, is a eutrophic filamentous fungus commonly isolated from soil, vegetation, polluted water, and animal feces in temperate climates. 6,16 It is now recognized as an emerging agent of severe fungal infections in immunosuppressed human patients. In humans, S. apiospermum has been classically implicated in subcutaneous infections and in asymptomatic pulmonary colonization, whereas systemic infections are more frequently observed in patients with an impaired immune system.…”