Concordance between direct microscopy and fungical culture for the diagnostic of feet's onychomycosis

Abstract

Prospective study compared the agreement between the direct microscopy and fungical culture from subungueal samples of the patients with clinical suspicion of feet's onychomycosis. The agreement occurred in 56.1% of the exams with dermatophytes, in 52.4% by others fungi and in 90.4% of the negative cases, 0,54 according to the Kappa`s test. In 39.3% of the onychomycosis caused by dermatophytes and 31.8% by nondermatophytes, these were identificated only for direct microscopy. The direct microscopic showed more sensibility compared with the culture, being superior in 19.5% of the total sample and maintaining agreement with the culture in 71.5% of the sample.

Onychomycosis: clinical, mycological and in vitro susceptibility testing of isolates of Trichophyton rubrum

“…, a positive rate of around 60% was found, and most cases were clinically characterized as DLSO. 14,15 These data are in agreement with literature reports that characterize DLSO as the most commonly observed clinical pattern. 16 .…”

“…(Kappa=0.54) and by Zanardi et al (Kappa=0.63) and is related to differences in sensitivity between the two techniques. 2,14,20 This difference, which arises from the higher positivity detected in DME compared to culture methods, has been found both in our study and in those conducted by other authors and results from the fact that positive results are observed in culture methods only when the microorganism reproduces to form fungal colonies, which requires fungi to be viable. Conversely, fungal viability is not required for achieving positive results in DME, a test that allows visualizing parasite fungal structures even they are not viable.…”

“…Conversely, fungal viability is not required for achieving positive results in DME, a test that allows visualizing parasite fungal structures even they are not viable. 2,14 Cases of onychomycosis whose samples were positive for DME and negative for fungal culture may also be attributed to culture contamination by anemophilous microorganisms that hamper the identification of the real etiologic agent. 20 …”

Descriptive analysis of mycological examination of patients with onychomycosis treated in private practice

“…The degree of agreement between DME and cultivation found in our study was moderate with kappa 0.603 (CI 0.4654 - 0.714) - calculated with the aid of the software EpiInfo version 7 -, higher than that found by Azambuja et. al 5 (kappa = 0.385) and statistically compatible with the work of Souza et al 9 (kappa = 0.54), and Zanardi et al 10 (kappa = 0.63). A higher DME positivity when cultures are compared - as seen in this study and in others - is expected by the fact that the positivity of the test depends only on the observation of parasitic structures.…”

Padrões de dermatoscopia da placa ungueal nas onicomicoses

“…A identificação da espécie por cultura é importante pois auxilia a estabelecer prognóstico e a direcionar o tratamento para o fungo envolvido, já que os fungos nãodermatófitos são reconhecidamente resistentes a terapia oral convencional 61. Souza et al62 analisaram concordância entre exame micológico direto e cultura para fungos em 890 exames para onicomicose das unhas dos pés. Seus resultados mostraram um nível de concordância moderado (kappa 0,54), ressaltando que o EMD identifica um maior número de casos positivos que a cultura e que no caso de um EMD negativo a cultura não aumenta significativamente o número de casos de onicomicose diagnosticados.…”