Biomedical Engineering Reference
In-Depth Information
infection of the keratin layer of the skin. The tinea lesions produced by
Hortaea wernickii are black because the organism produces melanin.
Melanin production is a feature that can help clinical mycologists identify a
fungal species. Species that produce melanin are called dematiaceous fungi.
Neotestudina is one of various genera that has been cultured from myce-
toma, an uncommon and enigmatic skin infection. Mycetoma, also known as
Madura foot and maduromycosis, occurs most often in India, Africa, and
South America. It presents as a slowly growing, fungating mass arising in
the subcutaneous tissues, usually of the foot. As the mass grows, draining
sinuses discharge fluid and hard grains (white, white-yellow, or black
grains). These masses often become superinfected, making it very difficult to
determine the primary pathogen that causes the disease. More than thirty
different species of bacteria and fungi have been grown from these lesions.
It has been claimed that black grain mycetomas is caused by Leptosphaeria
senegalensis, Madurella grisea, Madurella mycetomatis,orPyrenochaeta
romeroi. White grain mycetomas are reputedly caused by Acremonium spe-
cies, Aspergillus nidulans, Neotestudina rosatii,orPseudallescheria boydii.
White-yellow grain mycetomas are said to be caused by: Actinomadura
madurae, Nocardia asteroides, and Nocardia brasiliensis. Brown-red
grain mycetomas are said to be caused by: Actinomadura pelletieri or
Streptomcyes somaliensis. Taken at face value, these claims would indicate
that many different organisms, both bacterial and fungal, can produce a dis-
ease of remarkably specific, even unique, clinical features. Suffice it to say
that clinical science has much to learn about mycetoma.
Ascomycota
Pezizomycotina
Sordariomycetes
Microascales
Microascaceae
*Scedosporium
Hypocreales
Nectriaceae
*Fusarium
Sordariales
Incertae sedis (uncertain)
*Madurella
Scedosporium prolificans accounts for a sizable portion of the instances of
an uncommon lesion: disseminated phaeohyphomycosis. The prefix derives
from the Greek “phaeo,” meaning dusky. The suffix “hyphomycosis” indi-
cates that the fungal organism produces hyphae. Phaeohyphomycosis pre-
sents as one or more abscesses that are brown, on gross examination.
The fungi that cause phaeohyphomycosis (e.g. Scedosporium prolificans) are
dematiaceous (melanin-producing). Other genera of dematiaceious fungi that
