Hair perforation test is positive in infection with -
Hair perforation test

The hair perforation test consists of inoculating colonies of an organism into a dish containing a small amount of water, a few drops of yeast extract solution and some human hair. The dish is incubated at 300C and after 7 days, some of the hair is taken and are kept on a slide with a coverslip and are observed under a microscope. The test is considered positive if the hair has a deep, narrow wedge-shaped perforation in it.
Hair perforation test is done to distinguish between isolates of dermatophytes, particularly trichophyton mentagrophytes and its variants.
Trichophyton
Microsporum
Epidermophyton
All of the above