In vitro sensitivity of dermatophytes to urea.
OBJECTIVE
Urea is commonly used as a keratolytic substance in the treatment of onychomycoses to improve the penetration of antifungal drugs in the lesion sites. The aim of the present study was to investigate the inhibitory action of urea on samples of dermatophytes in vitro.


METHODS
Minimum inhibitory concentration of urea was determined for 31 samples of dermatophytes cultured in Sabouraud-dextrose broth containing different concentrations (7.5% up to 40%) of urea. Absence of growth was the criterion adopted to determine the minimum inhibitory concentration.


RESULTS
The majority of samples (87%) were sensitive to urea at 12.5%, or less. 2 isolates of Trichophyton tonsurans and 2 of Trichophyton rubrum required 30%, and 40% urea, respectively, to be completely inhibited.


CONCLUSIONS
In vitro results demonstrate inhibitory activity of urea on dermatophytes, suggesting that it could be used as an adjuvant in topical treatments.
Laboratory of Medical Mycology, Institute of Tropical Medicine (LIM 53), São Paulo University Medical School--São Paulo/SP, Brazil. jecm@usp.br
José Eduardo Costa
JE
Martins
Simone Miwa
SM
Corim
Giovanna Letícia Hernández
GL
Arriagada
Natalina Takahashi
NT
de Melo
Elisabeth Maria
EM
Heins
D000935:Antifungal Agents / Q000494:pharmacology*; D003470:Culture Media; D006801:Humans; D007641:Keratolytic Agents / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D008864:Microsporum / Q000187:drug effects*; D014249:Trichophyton / Q000187:drug effects*; D014508:Urea / Q000494:pharmacology*
D000935:Antifungal Agents; D003470:Culture Media; D007641:Keratolytic Agents; D014508:Urea