Trichophyton rubrum produces tear-shaped microconidia that are arranged along the conidiophore, generating a "birds on a telephone wire" appearance.
The top right image shows a T. rubrum culture plate demonstrating colonial morphology that is flat to cottony, and raised and ruffled at its center. The frontal coloration can range from white to bright yellowish-beige and even to a red-violet color. From the reverse, the colonies display a coloration that is light yellowish to brown, or reddish brown. The bottom right image shows a T. rubrum lactophenol cotton blue preparation showing a large, septate macroconidium, and numbers of smooth-walled, teardrop-shaped microconidia.
Images courtesy of the CDC.
