UTA Medical Mycology

Histoplasmosis

-mycotic infection of the reticuloendothelial system caused by the inhalation of the fungus

-All stages of this disease may mimic tuberculosis

-from soil enriched with excreta from chicken, starlings and bats

-rounded, single-celled, tuberculate macroconidia formed on short, hyaline, undifferentiated conidiophores

-grows on blood agar (intracellular infection)

Disseminated Histoplasmosis

Endemic to OHIO and MISSISSIPPI RIVER valleys

Lobomycosis

-remains to be cultured

-NO systematic spread

-chronic, localized, subepidermal infection characterized by the presence of keloidal (A red, raised formation of fibrous scar tissue caused by excessive tissue repair in response to trauma or surgical incision), verrucoid, nodular lesions or sometimes by vegetating crusty plaques and tumors

-found in humans and dolphins

-restricted to the Amazon Valley in Brazil, mostly men

Pityriasis (tinea) versicolor [Malassezia]

-a lipophilic yeast forming part of the normal flora of human skin.

-a chronic superficial fungal infection of the skin characterized by the well-demarcated white, pink, fawn, or brownish lesions, often coalescing and covered with thin furfuraceous scales

- The color varies according to the normal pigmentation of the patient, exposure of the area to sunlight, and the severity of the disease.

-Lesions occur on the trunk, shoulders, and arms, rarely on the neck and face, and fluoresce a pale greenish color under Wood's ultra-violet light

Dandruff [Malassezia]

Malassezia convert sebum triglycerides into irritating free fatty acids in vivo.

opportunistic, superficial infections and occasionally systemic infections

Mycetoma

-A mycotic infection of humans and animals caused by a number of different fungi and actinomycetes characterized by draining sinuses, granules and tumefaction

-disease results from the traumatic implantation of the aetiologic agent and usually involves the cutaneous and subcutaneous tissue, fascia and bone of the foot or hand

-Sinuses discharge serosanguinous fluid containing the granules which vary in size, color, and degree of hardness, depending on the aetiologic species, and are the hallmark of mycetoma

-worldwide, more common in bare footed region

-can be caused by fungus OR bacteria

Mycotic Keratitis

opportunistic fungal infection of the eye that causes ulceration and inflammation, usually the following trauma to the cornea by vegetative matter, soil or surgery

Paracoccidioidomycosis

-chronic granulomatous disease that characteristically produces a primary pulmonary infection, often inapparent, and then disseminates to form ulcerative granulomata of the buccal, nasal and occasionally the gastrointestinal mucosa

-geographically restricted to areas of South and Central America

-The disease in its inception and development is similar to Blastomycosis and coccidioidomycosis

-yeast resemble STEERLING WHEEL

-Dimoprhic fungi

Molluscum contagiosum

-propensity to cause disease in the normal host, as well as in immunosuppressed patients, but significantly, it has now become a major opportunistic pathogen in HIV positive patients in Indochina

-infection caused by a poxvirus(molluscum contagiosum virus).

-The result of the infection is usually a benign, mild skin disease characterized by lesions (growths) that may appear anywhere on the body. Within 6-12 months, Molluscum contagiosum typically resolves without scarring but may take as long as 4 years.

Phaeohyphomycosis

-infection of humans and lower animals caused by a number of dematiaceous (brown-pigmented) fungi where the tissue morphology of the causative organism is mycelial

-Clinical forms of the disease range from localized superficial infections of the stratum corneum (tinea nigra) to subcutaneous cysts (phaeomycotic cyst) to invasion of the brain

-tissue morphology is either a grain (mycotic mycetoma) or sclerotic body

Pseudallescheriasis and Scedosporium

-A spectrum of diseases similar in terms of variety and severity to those caused by Aspergillus

-vast majority of infections are mycetomas, the remainder include infections of the eye, ear, central nervous system, internal organs and more commonly the lungs.

o Scedosporium prolificans is distinguished from other members of the genus, in particular the human pathogen S. apiospermum, by having basally swollen, flask shaped annellides, slower colony formation on nutrient agar media, and by not growing on media containing cycloheximide (actidione)

Rhinosporidiosis

-chronic granulomatous disease characterised by the production of large polyps, tumours, papillomas, or wart-like lesions.

-The nose is the most commonly affected site.

-yeast like cells with elongated bud, pigmentation may vary, short conidiophores

Sporotrichosis

-commonly found in soil and on decaying vegetation.

-chronic mycotic infection of the cutaneous or subcutaneous tissues and adjacent lymphatics characterized by nodular lesions which may suppurate and ulcerate

commonly found in soil and on decaying vegetation.

Tinea nigra

-a superficial fungal infection of skin characterized by brown to black macules

usually occur on the palmar aspects of hands and occasionally the plantar and other surfaces of the skin. -

-Lesions are non-inflammatory and non-scaling

-more common in tropical regions of Central and South America, Africa, South-East Asia and Australia

Familial spread of infection reported

o a common saprophytic fungus believed to occur in soil, compost, humus an on wood in humid tropical and sub-tropical regions.

-Familial spread of infection reported

Subcutaneous zygomycosis (Mucormycosis)

-An acute and rapidly developing, less commonly chronic, infection of debilitated patients. Depending on the portal of entry, the disease involves the rhino-facial-cranial area, lungs, gastrointestinal tract, skin or less commonly other organ systems

-The infecting fungi have a predilection for invading vessels of the arterial system, causing embolization and subsequent necrosis of surrounding tissue

A suppurative, pyrogenic reaction is elicited; granuloma formation is not frequently encountered.

Mediastinal granulomatosis (histoplasmosis)

o Treatment for this is not recommended in asymptomatic patients; for symptomatic patients, itraconazole may be used for 6-12 weeks, although clinical trials to support this are lacking

o Antifungal therapy is not effective for fibrosing mediastinitis; corticosteroids and nonsteroidal antiinflammatory drugs (NSAIDSs) also are ineffective. Surgery is not recommended

o Antifungals are not recommended for pericarditis because it is an inflammatory reaction

o least common, but most severe, late complication of histoplasmosis. Many physicians believe mediastinal fibrosis to be an abnormal immunologic response to antigens released by the soil based fungus histoplasma capsulatum

Fibrosing mediastinitis (histoplasmosis) [syndrome]

o There are two types; [histoplasmosis] - related fibrosing mediastinitis, and [idiopathic fibrosing] mediastinitis which may have multiple causes unrelated to histoplasmosis

o Both types are rare disorders caused by proliferations of collagen, fibrosis tissue and associated inflammatory cells within the mediastinum (the space between the lungs), organism inducing this reaction

• Disseminated histoplasmosis (syndrome)

o The most common symptoms of disseminated histoplasmosis are fever, fatigue, and weight loss. Symptoms and signs may point to involvement of specific sites, such as the skin, oropharynx, GI tract, CNS, and adrenal glandsinated histoplasmosis

Treatment of histoplasmosis

itraconazole (mild infection), ampho B (moderate to severe infection)

Teleomorph

the sexual reproductive stage (morph) typically a fruiting body

Anamorph

an asexual reproductive stage (morph), often mold-like o When a fungus produces multiple morphologically distinct anamorphs these are called synanamorphs

Holomorph

anamorph + teleomorph