Posaconazole efficacy in a murine disseminated infection caused by Paecilomyces lilacinus

OBJECTIVES

We have compared the efficacy of posaconazole and amphotericin B in an experimental murine model of paecilomycosis.

METHODS

Immunosuppressed mice were treated with posaconazole at 25, 50, 75 or 100 mg/kg/day orally, amphotericin B at 1.5 or 3 mg/kg/day intraperitoneally or liposomal amphotericin B at 5 mg/kg/day intravenously. Treatment began 1 day after infection and continued for 10 days post-infection. Two strains of Paecilomyces lilacinus were tested.

RESULTS

Posaconazole at 50 mg/kg/day was the only treatment able to significantly reduce fungal loads in the spleens, kidneys and livers of the mice infected by each of the two strains.

CONCLUSIONS

The results suggest that posaconazole may have a clinical role in the treatment of disseminated paecilomycosis.

Cholesterol dependent and Amphotericin B resistant isolates of a Candida glabrata strain from an Intensive Care Unit patient

Here we report on two isolates of Candida glabrata recovered from urine samples collected from of an Intensive Care Unit patient. D1/D2 and ITS 1+2 rDNA sequence analysis confirmed its identification. The isolates were cholesterol dependent and resistant to Amphotericin B.

Different virulence of the species of the Pseudallescheria boydii complex

Pseudallescheria boydii sensu lato is a complex of species involved in severe human infections. We have evaluated, using a murine model, the virulence of 2 strains of each of the most representative species of the complex, i.e., P. boydii sensu stricto, P. minutispora, Scedosporium apiospermum, S. aurantiacum and S. dehoogii. We used two different inocula, i.e., 5 x 10(4) conidia/ml (for immunosuppressed animals) and 1 x 10(6) conidia/ml (for immunocompetent animals), which were administered intravenously. Scedosporium aurantiacum and S. dehoogii were the most virulent species, causing the death of 80% and 70% of the immunocompetent mice, respectively. The remaining species only killed 0-20% of the animals.

Actinomucor elegans var. kuwaitiensis isolated from the wound of a diabetic patient

The new variety of Actinomucor elegans var. kuwaitiensis, isolated from an open necrotic wound of a diabetic patient is described. This strain differed from the two previously described varieties of A. elegans, A. elegans var. elegans and A. elegans var. meitauzae by nearly 1% or more sequence divergence within D1/D2 regions of 28S rRNA and the ITS region of rRNA genes. Like the other two varieties, no zygospores were observed; however, there was evidence suggesting intersexual diploidy, a feature not described previously in this species. Additionally, A. elegans var. kuwaitiensis was pathogenic to white mice causing 100% mortality within 5 days.

Micafungin combined with fluconazole, an effective therapy for murine blastoschizomycosis

OBJECTIVES

To study the efficacy of micafungin combined with fluconazole in a murine model of disseminated blastoschizomycosis.

METHODS

Mice were treated with fluconazole at 40 or 80 mg/kg/day given orally, with micafungin at 10 mg/kg/day given subcutaneously or with a combination of micafungin with fluconazole at the doses described above. Treatment began 1 day after infection and continued for 6 days post-infection. Tissue burden studies were performed 1 day after the treatment finished. The experiments were performed with three different strains.

RESULTS

The two combinations tested significantly improved the survival of mice with respect to the control group and reduced the tissue burden significantly with respect to the control and their respective monotherapies in most organs tested. All animals that received the combination of micafungin with fluconazole at 80 mg/kg/day survived up to the end of the experiment.

CONCLUSIONS

The combination of micafungin with fluconazole is promising for the treatment of disseminated blastoschizomycosis.

Efficacy of a new formulation of amphotericin B in a murine model of disseminated infection by Candida glabrata

OBJECTIVES

Amphotericin B poly-aggregates are a new formulation of amphotericin B, which can be obtained cheaply. In this study, we tested the efficacy of this new formulation for treating a disseminated infection by Candida glabrata in a murine model.

METHODS

Mice were rendered neutropenic by intraperitoneal cyclophosphamide and intravenous 5-fluorouracil administration and infected intravenously with 2 x 10(8) cfu of C. glabrata. The efficacy of the new formulation of amphotericin B was evaluated by survival and tissue burden studies. The experiments were repeated using three different clinical strains of C. glabrata.

RESULTS AND CONCLUSIONS

Amphotericin B poly-aggregates showed an efficacy similar to that of amphotericin B deoxycholate and liposomal amphotericin B in the treatment of a disseminated murine infection by C. glabrata.

Rho1 has distinct functions in morphogenesis, cell wall biosynthesis and virulence of Fusarium oxysporum

Rho-type GTPases regulate polarized growth in yeast by reorganization of the actin cytoskeleton and through signalling pathways that control the expression of cell wall biosynthetic genes. We report the cloning and functional analysis of rho1 from Fusarium oxysporum, a soilborne fungal pathogen causing vascular wilt on plants and opportunistic infections in humans. F. oxysporum strains carrying either a Deltarho1 loss-of-function mutation or a rho1(G14V) gain-of-function allele were viable, but displayed a severely restricted colony phenotype which was partially relieved by the osmotic stabilizer sorbitol, indicating structural alterations in the cell wall. Consistent with this hypothesis, Deltarho1 strains showed increased resistance to cell wall-degrading enzymes and staining with Calcofluor white, as well as changes in chitin and glucan synthase gene expression and enzymatic activity. Re-introduction of a functional rho1 allele into the Deltarho1 mutant fully restored the wild-type phenotype. The Deltarho1 strain had dramatically reduced virulence on tomato plants, but was as virulent as the wild type on immunodepressed mice. Thus, Rho1 plays a key role during fungal infection of plants, but not of mammalian hosts.

Isolation ofCandida africana, probable atypical strains ofCandida albicans, from a patient with vaginitis

Identification of unusual fungal isolates is a major challenge for the clinical laboratory. This report describes the isolation of Candida africana from a patient with vaginitis. This is a doubtful species which possibly represents atypical strains of Candida albicans. Candida africana can be separated morphologically and physiologically from C. albicans but not genetically. The analysis of 26S rRNA gene showed near 100% homology between C. africana and C. albicans.

A study of the growth of Pseudallescheria boydii isolates from sewage sludge and clinical sources on tributyrin, rapeseed oil, biodiesel oil and diesel oil

The study compared the growth of Pseudallescheria boydii isolates from sewage sludge and from clinical sources on tributyrin, rapeseed oil, biodiesel oil and diesel oil agars. The isolates grew on all substrates tested. The highest growth was observed on rapeseed oil agar, while the lowest on diesel agar. On tributyrin agar, hydrolysis zones were observed around or underneath the colonies. On rapeseed oil agar, no hydrolysis zones were formed, while most isolates formed such a zone on biodiesel oil agar. Rapeseed oil and biodiesel oil stimulated the growth of P. boydii isolates, while tributyrin inhibited fungal growth. The stimulation or inhibition effect of diesel oil was dependent on the specified strain. In clinical isolates, fungal growth and activity were found to be more variable compared to sludge isolates. The data suggest that contamination of the environment with these oils could favor the growth of P. boydii. However, no association was found between the growth and oil utilization by this fungus and its pathogenicity.