The Hair Baiting Test differentiates which two Trichophyton species that produce red colonies on Sabouraud agar plates?

The Hair Baiting Test differentiates which two Trichophyton species that produce red colonies on Sabouraud agar plates?

• A. T. tonsurans and T. schoenleinii
• B. T. tonsurans and T. violaceum
• C. T. verrucosum and T. rubrum
• D. T. mentagrophytes and T. rubrum

Answer: (D)

The Hair Baiting Test relies on pigment production patterns when dermatophytes are grown on Sabouraud agar after using hair as a bait substrate. Some Trichophyton species will develop a red pigment that diffusely colors the colonies, and this trait is most reliably seen for two species in this setup: Trichophyton mentagrophytes and Trichophyton rubrum. Their red colonies on Sabouraud agar under these conditions provide a distinguishing clue that helps separate them from other dermatophytes, which either don’t produce the red pigment or show different coloration. Keep in mind that pigment can vary with incubation conditions and medium, so this test is used in conjunction with other morphological and cultural characteristics to confirm identity.

The Hair Baiting Test relies on pigment production patterns when dermatophytes are grown on Sabouraud agar after using hair as a bait substrate. Some Trichophyton species will develop a red pigment that diffusely colors the colonies, and this trait is most reliably seen for two species in this setup: Trichophyton mentagrophytes and Trichophyton rubrum. Their red colonies on Sabouraud agar under these conditions provide a distinguishing clue that helps separate them from other dermatophytes, which either don’t produce the red pigment or show different coloration. Keep in mind that pigment can vary with incubation conditions and medium, so this test is used in conjunction with other morphological and cultural characteristics to confirm identity.