Fungi that cause Piedra.

Piadra is an infection of scalp hair caused by piedraia hortae and Trichosporon beigelii. Colonization of hair shaft characterized by superficial nodules. No hair damage Black piedra and white piedra

Black piedra Piedraia hortae, the etiologic agent of black piedra. Found in tropical South and Central American, Southeast Asia, and Africa. Fungal colonization of the scalp hair. Hairs with visible nodules should be plucked, treated with KOH and examined under the microscope. The nodule should be crushed, taking care not to break the coverslip. The finding of septate brown hyphae, asci, and fusiform ascospores

Clinical findings: Discrete, hard, dark brown to black nodules on the hair, which are small brown-black nodules formed on the hair surfaces consisting of dark colored thick hyphae.

Microscopic examination: A diagnosis can be made by examining a potassium hydroxide preparation of a crushed nodule from an infected hair. Nodules are black, hard, and small. When crushed, the dark colored, branching, thick (4-8 µm) septate pigmented hyphae can be seen, usually with large oval asci , and ascospores (sexual spores).

Culture: Cultural techniques are not usually required to diagnose Piedra, but only in the case of confirming the diagnosis If done, should be on media with antibacterial agents, as well as media with both antibacterial agents and cycloheximide. If it performed, will give: Brown to black colonies

White piedra Fungal colonization of the coarse hairs of the body facial, axillary or genital hair The etiological agent is Trichosporon species (yeast-like organisms that form true hyphae, arthroconidia, and blastoconidia.) Different species infect different locations.

T. beigelii (White Piedra), unlike P. hortae, is not dark colored. White nodules are formed consisting of mases of non pigmented hyphae. Frequent in tropical and temperate zones, South America and parts of Africa and southern Asia, and other countries.

Clinical findings: Soft, white to yellowish nodules loosely attached to the hair.

Microscopic: Direct microscopic examination of hair nodules revealing these characteristics should be sufficient for diagnosis. A diagnosis can be made by examining a potassium hydroxide preparation of a crushed nodule from an infected hair. Nodules are white or pale brown and soft. When crushed 2-4 µm width Intertwined septate hyphae can be seen with arthrospores, Blasto- and arthroconidia

Culture: Cultural techniques are not usually required to diagnose Piedra, but if it performed, will give: Colonies appear rapidly (1–2 days) at 30°C on selective agar containing antibacterial agents. It will be Soft, creamy colonies

Species identification: Can be accomplished using commercially available assimilation kits, but should be used in conjunction with morphologic criteria (e.g., formation of arthroconidia and blastoconida). Diagnosis can be easily confirmed by direct microscopic examination of KOH mounted scrapings of involved skin or hair.

Pityriasis versicolor can be confirmed when both round, budding yeast cells and short fat hyphae (“spaghetti and meatballs”) are observed. Wood’s light examination may reveal bright yellow fluorescence. Fungal culture is not helpful as absolute diagnosis because the organism may occur in normal skin. Hair shafts from blackpiedra show masses of intertwined pigmented hyphae and occasional ascospores. In white piedra, there are masses of hyphae with numerous septa along with plentiful blastoconidia and arthroconidia.

Subcutaneous Mycosis: These are referred to as mycosis of implantation because they are acquired when the pathogen is inoculated through the skin by minor cuts or scratches or by thorn or splinter wounds

The principal subcutaneous mycoses are: Chromomycosis, caused by Phialophora species and Cladosporium carrionii. Mycetoma, caused by several species of fungi and actinomycetes. Subcutaneous Zygomycosis, caused by Basidiobolus or Conidiobolus species. Rhinosporidiosis: caused by Rhinosporiduim seeberi.