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.