Pathogenicity of some ordinarily harmless yeasts for cortisone-treated mice

Schwanniomyces etchellsii: an unusual cause of fungemia in a patient with cholecystitis

Schwanniomyces species are largely unrecognized as being pathogenic, and a paucity of published reports exist regarding their role as infectious agents. Here, for the first time, we describe a case of human infection caused by Schwanniomyces etchellsii in a patient with cholecystitis.

Isolation of Lodderomyces elongisporus from the Catheter Tip of a Fungemia Patient in the Middle East

Lodderomyces elongisporus is phenotypically closely related to Candida parapsilosis and has recently been identified as an infrequent cause of bloodstream infections in patients from Asia and Mexico. We report here the isolation of Lodderomyces elongisporus from the catheter of a suspected case of fungemia. The identity of the isolate was confirmed by phenotypic characteristics and ribosomal DNA sequencing.

Disseminated trichosporonosis in a burn patient: meningitis and cerebral abscess due to Trichosporon asahii

A 44-year-old diabetic female presented to a hospital in Jamaica with thermal burns. Trichosporon asahii was isolated from facial wounds, sputum, and a meningeal swab. Dissemination of the fungus was demonstrated in stained histological sections of the meninges and a brain abscess at autopsy. Pure growth of the fungus from patient samples submitted and an environmental isolate obtained from a wash basin in the hospital supported the diagnosis.

Fungal infection in a patient with multiple sclerosis

Multiple sclerosis (MS) is a chronic, inflammatory disease of the central nervous system, whose causes are still unknown. We have proposed that MS, as well as some ophthalmologic diseases, are associated with fungal infection. In the present study, we closely monitored a patient with MS over a three-year period. Antibodies against different Candida spp. were detected in peripheral blood serum, although the titer of these antibodies fluctuated. The presence of fungal macromolecules, such as proteins, polysaccharides, and DNA, was also tested. In several sera samples, antigens related to C. famata were evidenced by the slot-blot test using a rabbit polyclonal antibody against these species, while high levels of β-1,3 glucan were detected with the commercial Fungitell assay. Despite the variations by sample, we concluded that all fungal macromolecules, that is, proteins, polysaccharides, and DNA, were present in blood from the MS patient which was analyzed. Several fungal species were identified using polymerase chain reaction (PCR) followed by sequencing. Antibodies against Candida spp. as well as C. famata-related antigens were also detected in cerebrospinal fluid (CSF). Our findings provide support for the notion that disseminated mycosis is present in this patient.

Taxonomic position of clinical isolates of Candida famata

We examined five clinical isolates formerly classified as Candida famata to clarify their taxonomic position by DNA-DNA reassociation studies and several phenotypic features. Four of the five isolates, M 5101, M 5102, M 5111 and M 5112, produced ascospores after being grown for 1 week on YM agar at 20 degrees C. By the API 20C system, three of the five isolates were identified as C. famata, and the other two strains as C. guilliermondii/C. famata. The antigenic patterns of all the isolates examined with the Candida Check kit were similar to those of C. guilliermondii. Specific antiserum against C. saitoana was obtained by adsorption. However, none of the clinical isolates tested reacted with this adsorbed serum. The mol% G + C of the four sporulated isolates ranged from 35.8 to 37.7 and that of the remaining, non-sporulated, isolate M 2054 was 43.4. The DNA reassociation value was determined by the spectrophotometric method. M 5111 and M 5112 were identified as Debaryomyces hansenii var. hansenii, M 5101 and M 5102 as D. hansenii var. fabryi and M 2054 as C. guilliermondii. The ascospore formation was exclusive to the four isolates related to D. hansenii. These findings suggest that with the exception of C. guilliermondii the other C. famata isolates examined all belong to a single species, D. hansenii.

Pathogenicity of yeasts and algae isolated from bovine mastitis secretions in a murine model

The pathogenicity of strains of yeasts and algae isolated from bovine mastitis secretions was evaluated in immunosuppressed mice. Strains of Candida tropicalis (n = 3) were the most pathogenic, but all strains of Geotrichum capitatum (n = 5) and the colourless alga Prototheca zopfii (n = 5) were also lethal to mice at the highest dose of 1 x 10(7) CFU per mouse. Reisolation of the inoculated micro-organisms and the occurrence of histopathological lesions within organs of mice challenged with 1 x 10(3) to 1 x 10(7) CFU per animal revealed strains of C. krusei (n = 17), C. kefyr (n = 6) and C. rugosa (n = 6) to have a moderate pathogenicity, whereas strains of C. valida (n = 1) and C. catenulata (n = 2) were weakly pathogenic and non-pathogenic respectively.

Invasive Trichosporon beigelii infection in immunosuppressed rats

Fulminant systemic mycoses were seen as complications in rats undergoing drug trials for the treatment of Pneumocystis carinii pneumonia. Rats were immunosuppressed with corticosteroids and by feeding with a low-protein diet. Homogenized pulmonary tissue from a rat with pneumocystosis was inoculated transtracheally. Secondary invasive mycosis was found in 56 of 59 rats examined. Trichosporon beigelii was identified as the causative agent in the majority of cases. After examining possible sources of infection, a Pneumocystis inoculum contaminated with fungi was found to be the obvious source. T. beigelii infections are becoming increasingly significant in immunocompromised human patients. The need for suitable and reproducible animal models is therefore also increasing. Observations described in this paper may help in the further development of such models.

Disseminated trichosporonosis in a neutropenic murine model

Life-threatening disseminated infection with Trichosporon beigelii (trichosporonosis) is a rare mycosis most commonly seen in patients with hematologic malignancies made neutropenic by cytotoxic therapy. This infection is usually resistant to conventional antifungal therapies. Poor correlation between therapeutic outcome of trichosporonosis and in vitro susceptibility of clinical isolates of T. beigelii to antifungal agents is often reported. To obtain a better understanding of its pathogenesis, and to aid in the future study of the therapy of this disease, a murine model of trichosporonosis was developed. The in vitro growth of clinical isolates of T. beigelii was first studied. Subsequently, mice made neutropenic with cyclophosphamide were inoculated intravenously with the fungus to produce the disease model. Inoculum size which produced 100% mortality, yet allowed an apparent therapeutic window (6 x 10(6)) was determined. Tissue distribution and burden of organism during the course of infection was examined by viability and histopathologic studies. T. beigelii disseminated rapidly in this model, involving numerous organs including the heart, brain, kidneys, lungs, and liver. The heart and kidneys of the infected animals showed evidence of infection as early as 6 hours following inoculation. Further understanding of the pathogenesis of trichosporonosis in the neutropenic host was imparted by this study. This will aid in the future study of antibiotic treatment of this disease and its untreated progression.

Pathogenicity of Trichosporon capitatum for normal and irradiated mice and the efficacy of miconazole on experimental systemic trichosporosis in mice

The authors describe the course of experimental trichosporosis in normal and X-irradiated ICR mice after i.v. inoculation with Trichosporon capitatum. The irradiated animals were considerably more sensitive to infection than normal animals. The LD50 challenge dose used was by approximately two orders lower (1 X 10(3) c.f.u. ml-1) in irradiated mice than in control animals. The histopathological examination of the internal organs of the infected mice demonstrated that the greatest tissue damage was associated with the kidneys, liver and spleen. However, the infectious agent was also found in heart, lungs and brain. The degree of impairment of the tissues was dependent on the inoculation dose and on the irradiation status. Miconazole (50 mg kg-1) was administered i.p. immediately after inoculation with Ts. capitatum and resulted in an alteration of infection and prolonged survival time. Miconazole was ineffective when challenge dose were used which produced 100% mortality (1 X 10(6) and 1 X 10(4) c.f.u. ml-1 for normal and irradiated mice, respectively). With the use of these doses also the course of infection was nearly identical both in the miconazole-treated and untreated animals.

Torulopsis candida, a new opportunistic pathogen

We described the first documented case of intravenous-catheter-associated fungemia caused by Torulopsis candida (Candida famata). The microorganism was isolated from two blood cultures and one intravenous catheter tip in a bone marrow transplant patient. Both the intravascular cannula and the immunological status of the patient are believed to have played major roles in predisposing the patient to such an infection. Uneventful recovery occurred after the removal of the catheter and amphotericin B therapy.

Dissemination of yeasts after gastrointestinal inoculation in antibiotic-treated mice

Mice pretreated with antibiotics were inoculated intragastrically with different yeast isolates to determine whether the resulting disruption of the normal flora ecology would allow certain fungi to colonize and disseminate from the gastrointestinal tract. Antibiotic treatment decreased the total population levels of the indigenous bacterial flora, and predisposed mice to gastrointestinal overgrowth and subsequent dissemination by Candida albicans, C. parapsilosis, C. pseudotropicalis, C. tropicalis, and Torulopsis glabrata. A clinical isolate of Rhodotorula rubra, on the other hand, was unable to maintain a stable population in the gut of similar mice and could not be isolated from systemic organs. Control animals not receiving antibiotic therapy, challenged with C. albicans, showed significantly lower gut population levels of yeasts, and Candida organisms could not be grown from visceral organs. It is suggested that suppression of fungi within the gastrointestinal tract by members of the normal bacterial flora may be an important mechanism whereby fungi are confined to the alimentary tract.