Species distribution and antifungal susceptibility of 358 Trichosporon clinical isolates collected in 24 medical centres.

OBJECTIVES: To provide species distribution and antifungal susceptibility profiles of 358 Trichosporon clinical isolates collected from 24 tertiary-care hospitals. METHODS: Species identification was performed by sequencing the IGS1 region of rDNA. Antifungal susceptibility testing for amphotericin B, fluconazole, voriconazole and posaconazole followed the Clinical and Laboratory Standards Institute reference method. Tentative epidemiologic cutoff values (97.5% ECVs) of antifungals for Trichosporon asahii were also calculated. RESULTS: Isolates were cultured mostly from urine (155/358, 43.3%) and blood (82/358, 23%) samples. Trichosporon asahii was the most common species (273/358, 76.3%), followed by T. inkin (35/358, 9.7%). Isolation of non-T. asahii species increased substantially over the last 11 years [11/77 (14.2%) from 1997 to 2007 vs. 74/281, (26.3%) from 2008 to 2018, p0.03]. Antifungal susceptibility testing showed high amphotericin B minimum inhibitory concentrations against Trichosporon isolates, with higher values for T. faecale. The ECV for amphotericin B and T. asahii was set at 4 µg/mL. Among the triazole derivatives, fluconazole was the least active drug. The ECVs for fluconazole and posaconazole against T. asahii were set at 8 and 0.5 µg/mL, respectively. Voriconazole showed the strongest in vitro activity against the Trichosporon isolates; its ECV for T. asahii was set at 0.25 µg/mL after 48 hours' incubation. CONCLUSIONS: Trichosporon species diversity has increased over the years in human samples, and antifungal susceptibility profiles were species specific. Trichosporon asahii antifungal ECVs were proposed, which may be helpful to guide antifungal therapy.

Epidemiology and fungal species distribution of superficial mycoses in Northeast Brazil.

OBJECTIVE: Dermatomycoses are superficial fungal infections which affect the skin, hair and nails of humans and animals. Male and female patients of all ages are affected by this condition. The main etiological agents of dermatomycoses are the dermatophytes fungi of the genera Trichophyton, Microsporum and Epidermophyton, while the main yeasts belong to the genera Candida, Malassezia and Trichosporon. The variation in the distribution of dermatomycoses worldwide justify the conduction of epidemiological studies in order to contribute for the better understanding of patterns of mycological cutaneous infections. This study was conducted from April 2013 to December 2014. MATERIAL AND METHODS: A total of 205 patients were evaluated, while 235 clinical specimens were obtained. From our positive cases of mycological examination, 73 (64.6%) patients were female, while 40 (35.4%) were male. Scales from the skin and nails were collected and observed at optical microscopy after potassium hydroxide clarification. Cultures were performed on Sabouraud Dextrose Agar added chloramphenicol. Identification was performed by classic methodology. RESULTS: We found that the glabrous skin was the largest source of dermatomycoses (30.11%), followed by toenails (27.4%) and fingernails (17.7%). Regarding onychomycosis, the most affected population was over 50 years old. Trichophyton rubrum was the dermatophyte fungal species more commonly found. Most of the patients with pityriasis versicolor were adults and female. Another important fact observed is that Candida parapsilosis was the most prevalent species. Finally, a high incidence of T. tonsurans in cases of superficial mycoses was observed. CONCLUSION: Our results clearly demonstrate peculiarities in terms of etiological agents of dermatophytoses distribution in a specific region of Brazil.

Candida albicans GRX2, encoding a putative glutaredoxin, is required for virulence in a murine model.

Resistance of Candida albicans to reactive oxygen species is thought to enhance its virulence in mammalian hosts. Genes such as SOD1, which encodes the anti-oxidant, superoxide dismutase, are known virulence factors. We disrupted the gene GRX2, which encodes a putative glutathione reductase (glutaredoxin) in C. albicans, and we compared the mutant with an sod1Deltamutant. In vitro, the grx2Deltastrain, but not the sod1Delta strain, was defective in hypha formation. The grx2Deltastrain, but not sod1Delta, was significantly more susceptible to killing by neutrophils. When exposed to two compounds that generate reactive oxygen species, both mutants were susceptible to 1 mM menadione, but grx2Deltanull alone was resistant to diamide. Both mutants were attenuated in a murine intravenous challenge model, and a GRX2 reintegrant regained partial virulence. Emphasis on the putative function of products of genes such as SOD1 and GRX2 in resistance to oxidative stress may oversimplify their functions in the virulence process, since the grx2Deltastrain also gave defective hypha formation. Both mutants were sensitive to menadione and were slow to form germ tubes, though growth rates matched controls once the lag phase was passed.

Candida albicans GRX2, encoding a putative glutaredoxin, is required for virulence in a murine model

Resistance of Candida albicans to reactive oxygen species is thought to enhance its virulence in mammalian hosts. Genes such as SOD1, which encodes the anti-oxidant, superoxide dismutase, are known virulence factors. We disrupted the gene GRX2, which encodes a putative glutathione reductase (glutaredoxin) in C. albicans, and we compared the mutant with an sod1 Delta mutant. In vitro, the grx2 Delta strain, but not the sod1 Delta strain, was defective in hypha formation. The grx2 Delta strain, but not sod1 Delta, was significantly more susceptible to killing by neutrophils. When exposed to two compounds that generate reactive oxygen species, both mutants were susceptible to 1 mM menadione, but grx2 Delta null alone was resistant to diamide. Both mutants were attenuated in a murine intravenous challenge model, and a GRX2 reintegrant regained partial virulence. Emphasis on the putative function of products of genes such as SOD1 and GRX2 in resistance to oxidative stress may oversimplify their functions in the virulence process, since the grx2 Delta strain also gave defective hypha formation. Both mutants were sensitive to menadione and were slow to form germ tubes, though growth rates matched controls once the lag phase was passed.