Simple biochemical tests may be helpful in distinguishing T. rubrum from
T. mentagrophytes. While T. mentagrophytes grows profusely
on Dermatophyte milk agar (containing bromcresol purple),
T. rubrum growth is restricted. T. mentagrophytes is also
strongly urease positive within 7 days whileT. rubrum is urease
negative. The three tubes above contain T. rubrum and its
characteristic pattern: top) urea agar, middle) Dermatophyte milk agar,
bottom) Sab. dextrose growth control.
Copyright © 2001, William McDonald, M.D.
Revised: 23 March 2001