Isolamento, identificação e suscetibilidade in vitro de fungos causadores de onicomicose
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2010-02-24
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Universidade Federal de Goiás
Resumo
Onychomycosis is the nail infection caused by a wide spectrum of fungi species, including
yeasts, dermatophyte and filamentous fungi nondermatophytes (FFND). In this work, patients
with lesions nails from Dermatology Department in Clinics Hospital of the Federal University
of Goiás were studied. These patients were submitted to mycologic tests and the etiologic
agents identified were evaluated on in vitro activity for systemic antifungal agents. During the
period of March 2008 to March 2009, 114 patients clinically suspected of having
onychomycosis were examinated. The nail samples collected were submitted to direct
examination with potassium hydroxide 20% and grown in dextrose Sabouraud agar and
specific fungal pathogens agar. The antifungal susceptibility test was performed according to
the method of broth microdilution, recommended by the Clinical Laboratory Standards
Institute (CLSI), through M38-A and M27-A2 documents. The onychomycosis diagnosis was
established in 83.3% (95/114) patients, of which most were women between 40 to 59 years
old. The isolated fungi were identified as yeasts in 54.6%; dermatophytes in 28.7%; and
filamentous fungi nondermatophytes in 16.7%. Among yeasts, Candida parapsilosis was the
most common etiologic agent (52.5%); among dermatophytes, Trichophyton rubrum was the
most found (74.2), and among the filamentous fungi nondermatophytes, Fusarium spp was
the most isolated genus (44.4%). Both distal and lateral subungual lesions were predominant
in cases of onychomycosis by all the agents identified, showing that there was no correlation
with the clinical presentation and etiology. Although most of the isolates have showed
susceptible to several antifungal agents studied, five Candida spp strains were resistant; one
to voriconazole, one species to itraconazole and three to amphotericin B. The in vitro
susceptibility testing profile for dermatophytes was similar for each antifungal agent
analyzed. The minimal inhibitory concentration (MIC) of itraconazole, ketoconazole and
griseofulvin for 50% of isolates were lower than 1 μg/mL, and terbinafine was extremely low,
with concentration 0.015 μg/mL for 90% of isolates. The MIC for itraconazole in 90%
isolates of FFND was 16 g/mL, while for amphotericin B and voriconazole was 8 g/mL. In
summary, this study showed a higher frequency of onychomycosis in women. Candida spp
and dermatophytes with FFND emergence, especially of the genus Fusarium, were the main
fungi involved. Besides, the presence of resistant fungi to some antifungal agents showed the
need of using susceptibility tests for these fungi.
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ATAÍDES, Fábio Silvestre. Isolation, identification and in vitro susceptibility of fungi
that cause onychomycosis. 2010. 86 f. Dissertação (Mestrado em Medicina) - Universidade Federal de Goiás, Goiânia, 2010.