An 8-yrs-old male presents with multiple patches of alopecia and severe pruritus. A bright blue-green fluorescence is seen on examination of the scalp with a wood lamp. Pathogen most likely responsible is?
Tinea capitis is a dermatophyte infection of the scalp that may cause multiple patches of alopecia and severe itching. The dermatophytoses are diseases caused by a group of closely related filamentous fungi with a propensity for invading the stratum corneum, hair, and nails. Dermatophyte infections are designated by the word tinea, followed by the Latin name of the site. Thus, tinea capitis is a dermatophyte infection of the head. The three genera generally responsible for dermatophyte infections are Trichophyton, Microsporum, and Epidermophyton. Both Microsporum and Trichophyton species commonly cause tinea capitis. The most common pathogens are Trichophyton tonsurans followed by Microsporum canis. These two pathogens are distinguished by the fact that hairs infected with Microsporum species fluoresce a bright blue green color whereas those infected by Trichophyton species usually do not fluoresce. In addition, T. tousurans often causes a unique pattern on the scalp known as "black dot ringworm," characterized by circular patches of alopecia with hairs broken off close to the follicle. Epidermophyton species usually iuvade the iuteriginous skin, not the scalp. Epidermophyton floccosum is a cause of tinea crnsis, not tinea capitis. Neither Candida nor Aspergillus species are dermatophytes. Candida albicans is responsible for oral thrush and, in infants, diaper dermatitis. Aspergillus species are inhaled agents rather than skin pathogens.
Epidermophyton floccosum
Microsporum canis
Candida albicans
Trichophyton tonsurans