In Vitro Antifungal Susceptibilities of Uncommon Basidiomycetous Yeasts

Abstract

The in vitro activities of eight antifungal drugs against 50 isolates of basidiomycetous yeasts were determined by a microdilution method. In general fluconazole and micafungin were inactive. Terbinafine was active only against Sporobolomyces salmonicolor. The activities of the other antifungals were variable and depended on the species tested. The new triazoles showed the lowest MICs, but amphotericin B and itraconazole were the only drugs active against Cryptococcus albidus.Basidiomycetous yeasts are anamorphs (asexual states) of members of jelly fungi (Tremellales) or smuts (Ustilaginales). Some of these yeasts, such as Cryptococcus neoformans and Malassezia spp., are well-known human pathogens. However, many other species are also able to cause human infections, mainly in immunosuppressed patients. Among these, Cryptococcus albidus, Cryptococcus laurentii, Sporobolomyces salmonicolor, Rhodotorula glutinis, and, more commonly, Trichosporon asahii have been reported to cause severe infections (1,4,10,12,19,23). In general the most common treatment for yeast infections is based on the use of amphotericin B (AMB) and fluconazole (FLC). However, against infections caused by the five above-mentioned species, these drugs have repeatedly failed (3,5,7,12,13,21). Such a limitation, associated with AMB toxicity, determines the interest in evaluating the potential antifungal role of the new azoles and echinocandins. Although some of these species have been tested in vitro, only the responses of a reduced number of isolates are known (6,24). Trichosporon has received the most attention (2, 3, 21-23), but in most studies the strains tested were identified as Trichosporon beigelii, which is a not valid name, and so it is not known which current species were actually tested.In this study we have evaluated the in vitro activity of eight antifungal drugs against the five opportunistic species mentioned above. Although a reference method for testing these species does not exist, we have used M27-A2 (17), which has been shown to be very useful for testing the more-common yeasts.A total of 50 isolates were tested (10 species each of C. albidus, C. laurentii, R. glutinis, S. salmonicolor, and T. asahii). Most of them are clinical isolates provided by the BCCM/ IHEM Biomedical Fungi/Yeast collection or Centraalbureau voor Schimmelcultures. The isolates were stored lyophilized and were subcultured on Sabouraud dextrose agar for the study. T. asahii, S. salmonicolor, and R. glutinis were incubated at 35°C for 24 to 72 h, and C. albidus and C. laurentii were incubated at 30°C for 48 to 72 h. Candida krusei ATCC 6258 and Candida parapsilosis ATCC 22019 were included in each batch of tests as a quality control.Antifungal agents were obtained as pure powders. AMB (USP, Rockville, Md.), albaconazole (ABC; J. Uriach & Cía, Barcelona, Spain), voriconazole (VRC; Pfizer Inc., Madrid, Spain), itraconazole (ITC; Janssen Pharmaceutica, Beerse, Belgium), ravuconazole (RVC; Bristol-Myers Squibb Company, New Brunswick, N.J.), and terbinafine (TBF...

In vitro susceptibility to antifungal agents of environmental Cryptococcus spp. isolated in the city of Ribeirão Preto, São Paulo, Brazil

“…Most cases of C. neoformans meningitis resistant to the drug were reported in AIDS patients after long treatment periods and prophylaxis (Franzot & Hamdan 1996, Alves et al 2001. MIC ranges for fluconazole were quite wide for all strains, but were smaller for C. laurentii suggesting that the antifungal is more active in this strain, which confirms previous results reported by Garcia-Martos et al (2002) and Serena et al (2004).…”

“…Most strains of C. laurentii were sensitive to the drug confirming results by Garcia-Martos et al (2002). Other reports indicate different resistance levels to itraconazole in clinical C. laurentii isolates (Bauters et al 2001, Chen et al 2001, Averbuch et al 2002, Serena et al 2004.…”

Case Report of Cryptococcus Albidus Peritonitis in a Peritoneal Dialysis Patient and a Review of the Literature

“…In our patient, treatment with that agent was successful. It is important to note that C. albidus also exhibits susceptibility to flucytosine, posaconazole, fluconazole, voriconazole, itraconazole, and miconazole in some cases (10,11,13,19,(27)(28)(29). Because of these variations in C. albidus antifungal susceptibility, treatment should ideally be tailored to the individual disease-causing organism.…”

“…Lessons learned from the more general issue of cryptococcal peritonitis provide further guidance on therapeutic choices for C. albidus peritonitis, given that C. albidus and C. neoformans (the more common culprit in cryptococcal peritonitis) share susceptibility to amphotericin B at similar minimum inhibitory concentrations (2,27,30). The mainstays of fungal peritonitis management are rapid peritoneal fluid exchanges to minimize gross turbidity and the risk of adhesions, early removal of the catheter, and concurrent parenteral antifungal treatment (24).…”

Isolation of Rhodotorula mucilaginosa from skin lesions in a Southern sea lion (Otaria flavescens): a case report

“…It should be borne in mind that different environmental factors could cause stress to the animal and contribute, directly or indirectly, to In spite of the increasing importance of infections due to Rhodotorula spp., there are few publications reporting the in vitro susceptibility of Rhodotorula strains to antifungal agents with a standardized method (Gomez-Lopez et al, 2005;Tuon and Costa, 2008). These yeasts seem to be resistant to some therapeutic agents, especially to azoles and echinocandins (Galan-Sanchez et al, 1999;Preney et al, 2003;Zaas et al, 2003;Serena et al, 2004;Gomez-Lopez et al, 2005;Savini et al, 2008). Sertaconazole is a topical antifungal of the azole family (Carrillo-Munoz et al, 1999;Pfaller and Sutton, 2006).…”