Causative organism of Boggy swelling of hair:
Ans. A. Trichophyton mentagrophytesExplanationDERMATOPHYTOSES (tinea or ringworm) is the most common superficial mycoses affecting skin, hair, nail caused by group of fungi called dermatophytes.Trichophyton species: Infect skin, hair, nail.Microsporum species: Infect skin and hair.Epidermophyton species: Infect skin and nail.Depending on habitat, they are classified as follows:Anthropophilic: These fungal species exclusively affect humans.Zoophilic: They infect animals and birds.Geophilic: These fungal species are isolated from soil.Pathogenesis: Fungal spores are acquired by direct contact with soil, animals, humans infectedIn skin, they grow in centrifugal pattern in the stratum comeum forming characteristic annular or ring shaped pruritic lesionsThey invade hair shaft from within or from outside leading to alopecia:In nails, they invade through lateral or superficial nail plates.Clinical types of dermatophytoses:Clinical typesArea involvedTinea capitis (scalp infection): Scaly patches on scalp with broken hair. It is of following types:1. KerionPainful inflammatory reaction producing boggy lesions.Agent: Trichophyton verrucosum, Trichophyton mentagrophytes.2. FavusCup like crust (scutula) around infected hair follicle. Agent: Trichophyton schoenleinii.a.-Ectothrixb.-EndothrixArthrospores on the surface of hair shaft Agent: M. audouinii, M. canis, T. mentagrophytes.Arthrospores formed within the hair, filling the hair shaft leading to alopecia. Agent: T. tonsurans and T. violaceum.Tinea corporis Tinea pedis (athlete foot) Tinea cruris Cock itch) Tinea barbae Tinea facieiInfection of non-hairy skin of body (trunk and limbs)Infection of web space of foot later spreading to sole (moccasin pattern.) Infection of groin area.Infection of beard and moustache area of face.Infection of non-bearded area of face.Tinea imbricateConcentric lesions of skin agent: T. concentricumTinea unguiumInfection of nail bed agent: T. mentagrophytes, E. floccosumTinea manuumInfection of palmar aspect of hands.Laboratory diagnosis:Wood's lamp examination: Sample-skin scrapings, hair plucks, nail clippings.Direct examination: KOH mount using 10% from skin scrapings or 20-40% for nail clippings.Culture: on Sabouraud dextrose agar with cycloheximide. Macroscopic features like growth rate, texture, pigmentation- microscopic features appreciated by LPCB mount.Hair perforation test is positive for T. mentagrophytes and M. canis.Urease test positive for T. mentagrophytes.Molecular methods: PCR.Treatment: Oral terbinafine or itraconazole, whitfield ointment or tolnaftate.
Trichophyton mentagrophytes
E. flocosum
M. canis
T. concentricum
Mycology