Phialemonium

Abstract: Several members of the fungal genera Phialemonium and Lecythophora are occasional agents of severe human and animal infections. These species are difficult to identify, and relatively little is known about their frequency in the clinical setting. The objective of this study was to characterize morphologically and molecularly, on the basis of the analysis of large-subunit ribosomal DNA sequences, a set of 68 clinical isolates presumed to belong to these genera. A total of 59 isolates were determined to be Phialemonium species (n = 32) or a related Cephalotheca species (n = 6) or Lecythophora species (n = 20) or a related Coniochaeta species (n = 1). Nine isolates identified to be Acremonium spp. or Phaeoacremonium spp. were excluded from further study. The most common species were Phialemonium obovatum and Phialemonium curvatum, followed by Lecythophora hoffmannii, Cephalotheca foveolata, and Lecythophora mutabilis.

Abstract: Two fungal isolates recovered from the blood of two immunosuppressed patients are described as Phialemonium curvatum. One patient died, while the other, who was infected with Exophiala jeanselmei at the same time, survived after successful treatment with itraconazole. Analysis of internal transcribed spacer sequences demonstrated that the isolates belonged to the same strain and that the source of infection was probably a catheter. The taxonomic position of P. curvatum is discussed, and Phialemonium dimorphosporum is considered a synonym. The in vitro inhibitory activities of six antifungal agents (amphotericin B, itraconazole, ketaconazole, miconazole, flucytosine, and fluconazole) were determined against seven isolates of Phialemonium. Except for flucytosine, all of them were remarkably effective. Phialemonium should be added to the list of potential causes of nosocomial fungemia in cancer patients.

Abstract: Two cases of human fungal infections caused by members of the genus Phialemonium, a genus proposed by Gams and McGinnis (1983) for fungi intermediate between the genera Acremonium and Phialophora, are presented. The first case was a phaeohyphomycotic cyst on the foot of a renal transplant recipient. The fungus was detected by direct examination and histopathology and was recovered by several procedures over 4 months. It was flat, glabrous, and white becoming yellow with the production of a diffusible yellow pigment; it had conidiophores that were mostly solitary and lateral and terminal phialides and adelophialides with distinct collarettes producing cylindrical to curved conidia. The isolate resembled both Phialemonium dimorphosporum and Phialemonium curvatum, although its characteristics were more consistent with those of the latter. The second case was peritonitis in a renal transplant recipient. The fungus was white-to-cream colored and yeast like, but later became black with a green diffusible pigment, and produced obovoid conidia; it was easily identified as Phialemonium obovatum. Difficulties encountered in the identification and taxonomy of members of this genus highlight the need for standardized conditions, e.g., potato dextrose agar culture incubated at 24 to 25 degrees C for morphologic comparisons, to control significant variations due to culture conditions. Images

Abstract: Infections caused by rarely encountered fungal pathogens have increased in recent dec- ades. The present study describes a disseminated infection caused by Phialemonium curvatum , and reviews the literature in an effort to summarize prior experiences with this unusual pathogen. The clinical and microbiological characteristics of a new case due to Phialemonium are presented. The case is analysed with 19 other which have appeared in the literature since 1986. Ten cases were sporadic infections, while the others were associated with three small outbreaks. In all but our patient the skins natural barrier was compromised (15/20 (75%)) and immunosuppression was a factor in the majority of cases (14/20 (70%)). Dissemination was noted in 83% (5/6) of the immunocompetent patients and in 57% (8/14) of immunocompromised patients. Endocarditis was the most frequent form of infection (8/20 (40%)). Blood cultures were positive in 92% (12/13) of those with disseminated disease. The mortality rate was 54% (7/13) among those with disseminated infections, but fatal outcomes were not observed in patients receiving treatment with itraconazole, voriconazole or posaconazole. The in vitro susceptibility of Phialemonium indicated a more consistent level of activity for voriconazole and posa- conazole. Although infections usually occur when there is a breakdown in the skin the skin barrier or host defences are weakened, our case points out that infections due to Phi- alemonium species may occur in patients without these risk factors. The most frequent form of Phialemonium infections is endovascular, often with endocarditis and positive blood cultures, associated with high mortality rates. Treatment with the new triazoles is associated with improved survival.