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Home • SYLLABUS FOR MEDICAL MYCOLOGY - FALL 2008 • Intro to Fungi - PPT • Biology of Fungi • Poisonous Mushrooms • Mycotoxins and Health • Antifungal Agents - PPT • Antifungal Agents - HTM • superficialmycoses2008.html • Cutaneous Fungal Infections - PPT • Cutaneous Fungal Infections.pdf • Subcutaneous Mycoses • True Pathogenic Fungi & Opportunistic Fungi Mycoses • MEDICAL MYCOLOGY STUDY QUESTIONS.doc • MEDICAL MYCOLOGY STUDY QUESTIONS.pdf
Usually the result of traumatic implantation of fungus into
skin. Lesion develops at the site of the lesion.
- Mycetoma
(clincal syndrome of localized, indolent, deforming,
swollen lesions and sinuses, involving cutaneous and subcutaneous tissues,
fascia, and bone; usually occurring on the foot or hand) - etiologic agent
may be bacterial or fungi. Discussion here will be restricted to fungal
mycetoma.
- Chromoblastomycosis
(subcutaneous and cutaneous tissues of the hands and
feet).
- Phaeohyphomycosis
(face, cornea of eye, subcutaneous and cutaneous part of skin, occasionally
cerebral and systemic)
- Sporotrichosis
(cutaneous and subcutaneous tissues and adjacent lymphatics that suppurate,
ulcerate and drain)
- Lobomycosis
(subcutaneous and cut. tissues over different parts of
body).
- Rhinosporidiosis
(nasal cavities, mucocutaneous tissue - rarely it does effect the vagina,
penis, anus, ears, and throat region)
Mycetoma -
clincal syndrome of localized, indolent, deforming, swollen lesions and sinuses,
involving cutaneous and subcutaneous tissues, fascia, and bone; usually
occurring on the foot or hand) - etiologic agent may be bacteria or fungi.
- one potential causal agent can be
Pseudallescheria boydii, a soil/water inhabiting fungus with worldwide
distribution. However other fungi can be involved.
- fungi associated with fungal mycetoma are opportunistic
- mycotic mycetoma - usually more common in men (3:1 to 5:1) than in women
- usually results from trauma or puncture wounds to feet, legs, arms and
hands (usually on the feet)
- starts out as tumor-like to subcutaneous swelling
- ruptures near the surface; infects deeper tissues including subcutaneous
tissues and ligaments (tendons, muscles and bone are usually spared)
- small particles or grains leak out of the lesions - these represent the
to yellowish microcolonies
- lesions of mycetoma seldom heal spontaneously
- disease is chronic may continue for 40-50 years
- P. boydii is resistant to all systemically useful drugs,
including amphotericin B, KI, 5-fluorocytosine, 2-hydroxystilbamidine
- ketoconazole appears to be ineffective in clinical trials
- intravenous miconazole (9 mg per Kg of body weight sometimes higher
doses) shows promise
- surgery and removal of tumor ( if small it is encapsulate, if larger
amputation my be required)
- Combining miconazole and surgery may prove useful in effectively
treating the disease.
Chromoblastomycosis -
chromomycosis or verrucous dermatitis.
- Disease is one of hyperplasia, characterized by the formation of
verrucoid (rough), warty, cutaneous nodules, which may be raised 1-3 cm
above the skin surface. The roughened, irregular, pedunculated vegetations
often resembles the florets of cauliflower
- This disease is caused by Fonsecaea pedrosoi and Phialophora
verrucosa (identical to Cadophora americana which causes bluing
of lumber), both of which are dematiaceous fungi (darkly pigmented)
- occurs rarely in animals (such as, horses, cats, dogs, and frogs)
- soil-inhabiting fungi
- susceptibility enhanced by going barefoot or wearing sandals
- found almost exclusively in laborers
- enters hand or feet after trauma
- found primarily in the tropics or subtropics
- dull red or violet color on skin may resemble a ringworm lesion
- develops into a verrucous lesion
- pruritus (itchiness) and papules may develop
- fungus gets under the skin (produces bumps)
- bumps may block lymphatic system and cause elephantiasis
- sometimes bacterial infection may enter and cause a secondary infection
- rarely this fungus spreads to other areas of the subcutaneous tissue.
- potentially may spread to brain (life-threatening in that case)
Identification
- biopsy tissue - look at the skin for fungus
- hematoxylin stain - look for fungal cells scattered among skin cells
- attempt to culture fungus from biopsy tissue must always take place to
identify the etiological or causal agent
- colonies of fungi are dark or blackish
- Two species implicated in this mycosis - each may produce several spore
types
- Fonsecaea pedrosoi - Cladosporium type and Rhinocladiella
type of conidiation
- Phialalophora verrucosa - Phialophora type (flowers in the
vase conidiation)
- fungi found growing on plant debris, wood, soil.
Treatment
- usually not fatal or necessarily painful
- unsightly disease
- no really good cure
- thiabendazole - shows promise (given orally and on skin mixed with
dimethyl sulfoxide [DMSO] - to deliver drug) - experimental drug
- surgical excision, electrodesiccation, or cryosurgery are useful in
early stages of disease
- application of heat to infect site has been reported to effect a cure of
the disease after six months of treatment (using pocket warmers)
- itraconazole shows promise in clinical trials.
Phaeohyphomycosis
- amalgam of clinical diseases caused by a wide variety of dematiaceous
fungi
- characterized by the presence of brown pigmented fungal elements in host
tissue
- etiologic agent varies, and can be represented by a number of different
fungal species
- infections may vary from being superficial and contained in the
stratum corneum of the skin, to cutaneous and subcutaneous.
- in rare instances infections may become invasive systemic (invading
various organs) and/or cerebral
- in diagnosis, materials from cysts, nodules, abscesses and other
infected tissues may be examined under the microscope directly with 10% KOH.
The fungi are usually pigmented dark brown to hyaline
- if possible, material can be subcultured onto a selective isolation
medium, for several weeks at room temperature; identification of genus and
species is made, based on morphological and cultural characteristics
- the name, "Phaeohyphomycosis" is not meant to
supplant established clinical names of diseases, particularly when the
etiological agent is known
- treatment usually involves surgical excision of fungus and treatment of
with antifungal drugs (amphotericin B, 5-fluorocytosine, ketoconazole, or
another imidazole).
Sporotrichosis
(Gardener's disease)
- Sporotrichosis is most commonly a chronic
infection characterized by nodular lesions of the cutaneous or subcutaneous
tissues and adjacent lymphatics that suppurate, ulcerate, and drain
- the etiologic agent, is Sporothrix schenckii
- the fungus is found distributed throughout the
world
- the fungus gains entrance into the body through
traumatic implantation into the skin or rarely, by inhalation into the
lungs.
- first case presented with the clinical picture of
sporotrichosis was recorded by Schenck in 1898 from Johns Hopkins Hospital
in Baltimore
- Epidemics of sporotrichoisis have been reported
from time to time.
- In South Africa, over the space of two years,
almost 3000 cases occurred involving miners who brushed against timbers of a
mine shaft on which the fungus was growing. The epidemic was terminated by
treating the timbers with a fungicide.
- An epidemic occurred among brickyard workers who,
after the drinking much beer, began tossing bricks at each other, causing
many skin abrasions.
- The disease may be found in other animals,
including horses.
- The fungus gains entry into the body through some
trauma to the skin.
- The fungus is a saprophyte on plant debris
- scratches from thorns or splinters, cuts while
handling potting soil, sphagnum moss, or grasses allow the fungus to gain
entrance into the body
- This diseases has also occurred following cat
scratches, parrot bites, dog bites, insect stings, injury by metal
particles, handling fish, hammer blows, etc.
- occupational hazard of greenhouse workers and rose
growers
- Lymphocutaneous sporotrichoisis comprises up to
75% of all cases in most literature surveys.
- first sins of infect may appear as soon as
five days later
- the average incubation time is three weeks.
- The first sign of disease is the appearance of
a small, hard, movable nontender and nonattached subcutaneous nodule. as
the disease progresses in may become chronic, the lymphatics that drain
the area of the initial lesion are involved
- Fixed cutaneous sporotrichoisis
- lesions manifest themselves as ulcerative,
verrucous, infiltrated, or erythematoid plaques, or as scaly patchy,
macular, or papular rashes that to not involve local lymphatics and
remain "fixed"
- Mucocutaneous, extracutaneous, disseminated and
pulmonary sporotrichoisis do occur but these are relatively rare.
- potassium iodide (KI) administered in milk is the
drug of choice
- immersion of infected regions in hot water and
battery-operated "pocket warmers" have been utilized to bring about
resolution of the disease
- amphotericin B is the most effective drug used for
the treatment of relapsed lymphocutaneous sporotrichosis and pulmonary and
disseminated disease.
- Fungus is diphasic, and will convert from a
filamentous phase to a yeast phase when grown at a higher temperature (37°C).
Filamentous phase is hyaline, and produces delicate conidiophores and
conidia. Yeast phase is relatively nondescript, but budding yeast often
irregularily-shaped to broadly elliptical (cigar bodies).
Lobomycosis or Lobo
disease - etiological agent is Loboa loboi (yeast-like
organism that has never been cultured)
- Disease is chronic, localized, subepidermal infection characterized by
the presence of keloidal, verrucoid, nodular lesions or sometimes by
vegetating crusty plaques and tumors.
- despite the name, the disease does not refer to an infection spread by
wolves, or in any ways is it wolf-like.
- disease first describe in patient known as Jorge Lobo (1931)
- found in humans and dolphins.
- many cells are found in skin tissue
- chains of yeast cells form in tissue
- keloids are formed (mass of hyperplastic, fibrous, connective tissue,
usually at the site of a scar)
- disease resembles blastomycosis or paracoccidiomycosis
- cells are hyaline (not pigmented)
- common in Amazon natives or rarely in northern South American or Central
American people off the coast of Florida are found dolphins, have lesions
which resemble LOBO.
- what can be done? Not much, except perhaps surgery.
Rhinosporidiosis
- infection of mucocutaneous tissue caused by
Rhinosporidium seeberi
- fungus has never been cultured, although current
evidence suggests that it is a lower aquatic fungus - a "chytrid"
- In arid countries most infections are ocular, and
dust is postulated to ba vector
- disease has been recorded in primarily in India,
Ceylon, the Middle East, but also in South America, the U. S., and in almost
every other country of the world.
- age of patients varies from 3-90 some years, most
patients are between 20 and 40 years of age when diagnosed
- males account for 70-90% of cases, although this
varies depending on age, site of infection, and geographic location.
- eye infections seem to be more common in women
- nasal, ocular, and other mucocutaneous regions may
show signs of disease manifested as polyps and tumors
- Treatment involves surgical remove of affected
tissue
- local injection of amphotericin B may be used as
an adjunct to surgery to prevent reinfection and spread, although no studies
have substantiated it's effectiveness
- In tissue, the fungus produces spherules that
possess a thick wall; endospores are contained within.
This web page is organized and maintained by M. Huss. Last updated 8-06-08.
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