clinical groupings for fungal infections

8/3/2019 Clinical Groupings for Fungal Infections

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1. The Superficial Mycoses

2. The Cutaneous Mycoses

3. The Subcutaneous Mycoses

4. Dimorphic Systemic Mycoses

5. Opportunistic Systemic Mycoses


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These are superficialcosmetic fungal infections of

the skin or hair shaft. No living tissue is invaded

and there is no cellularresponse from the host.

Essentially no pathologicalchanges are elicited.

These infections are often

so innocuous that patients areoften unaware of theircondition.


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Caused by Malassezia

furfur.

Infects the stratum corneumepidermidis and causes

hypopigmentation or

hyperpigmentation on thetrunk of the body. Scaly

patches of skin fluoresce with

Woods lamp.


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The diagnosis is confirmed

by direct microscopic

examination of scrapings ofinfected skin, treated with 10

20% KOH or stained with

calcofluor white.

Characteristic spaghetti

and meatballs morphology is

observed microscopically. Blunt

ended short hyphae and

clusters of spherical spores.


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A lipid oil overlay is

required for culture because

Malassezia species arelipophilic yeasts, and most

require lipid in the medium for

growth.

Treated with daily

applications of selenium

sulfide. Topical or oral azoles

are also effective.


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Superficial infection of the

stratum corneum epidermidis

caused by the dermatiaceousfungus, Exophiala werneckii.

The infection ischaracterized by brown to

black, non-scaly patches on

the palms of the hands.


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Black, yeasty coloniesdevelop short olive graymycelia with age.

Microscopically, darkseptate hyphae with one- ortwo-celled blastoconidia are

demonstrated in clusters alongthe hyphae. The fungushydrolyzes casein.

Treated with keratolyticsolutions, salicylic acid, orazole antifungal drugs.


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Infection of the hair shaft

that produces hair breakage.

Treatment is cutting or

shaving infected hairs and use

of topical antifungals.

Infections may disseminate

in immunocompromisedindividuals.


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Caused by Trichosporonbeigelli.

Forms soft, light brownnodules around the beard andmustache hairs.

Microscopically, the fungus

demonstrates hyaline hyphaewith blastospores andarthrospores on CMT 80 agar;

crushed nodules in KOH showhyaline hyphae andarthrospores.


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Caused by Piedraia hortae

Forms firmly attached hard,

black nodules around the outside ofscalp hairs.

Microscopically, it producesdark thick-walled hyphae withswellings (chlamydospores) inculture; crushed nodules in KOHpreparation show numerous ovalasci, containing 2-8 aseptateascopores which are spindle-shaped(fusiform) and have a filament ateach pole.


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Caused by fungi that infect only

the superficial keratinized

tissue (skin, hair, and nails).


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Usually caused by dermatophytes (infectonly the superficial keratinized tissue - skin,hair, and nails) belonging to the 3 genera:

o Microsporum- affects skin and hair

o Trichophyton- affects skin, hair and nails

o Epidermophyton- affects skin and nails


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Dermatophytes are unable to grow at37 C or in the presence of serum.

Some cutaneous mycoses can also be

caused by Candida species.

No living tissue is invaded, however a

variety of pathological changes occurin the host because of the presence of

the infectious agent and its metabolic

products.


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Infections are commonly referred to as

tinea infections or dermatophytoses.

Ringworm is another name for

dermatophytic infections.


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Dermatophytes are classified depending on

whether their usual habitat:

Geophilicsoils

Zoophilicanimals

Anthropophilichumans


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Geophilic soils Zoophilic - animals Anthropophilic humans

Microsporum gypseum Microsporum canis (dogs and cats)

Microsporum gallinae (fowl)

Microsporum nanum (pigs)

Trichophyton equinum (horses)

Trichophyton verrucosum (cattle)

Trichophyton mentagrophytes var

mentagrophytes (rodents)

Epidermophyton floccosum

Microsporum audouinii

Trichophyton mentagrophytesvar interdigitale

Trichophyton rubrum

Trichophyton schoenleinii

Trichophyton tonsurans

Trichophyton violaceum


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Disease Causative organisms Incidence

Dermatophytosis

Ringworm of the

scalp,

glabrous skin and

nails.

Dermatophytes (Microsporum,

Trichophyton, Epidermophyton)Common

Candidiasis of skin,

mucous membranes

and nails.

Candida albicans and related species. Common

Dermatomycosis

Non-dermatophyte moulds

Hendersonula toruloidea

Scytalidium hyalium

Scopulariopsis brevicaulis

Rare


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Tinea is transmitted via the feet by

desquamated skin scales insubstrates like carpet and matting . Tinea of the nails caused

byT. rubrum


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Sub-mammary tinea corporis

caused by E. floccosum

Tinea of the beard "Tinea barbae"

caused by T. rubrum


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Diagnosis is made by macroscopic and microscopicobservations of the fungi and location of theinfection in the body.

Dermatophytes are identified by their colonialappearance and microscopic morphology aftergrowth for 2 weeks at 25 C on Sabouraud'sdextrose agar.

Microscopically, the fungi demonstratemicroconidia and macroconidia. Both conidiatypes or only one type may be demonstrated by afungus.


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may infect hair, skin, or nails

develop cylindric, smooth-walledmacroconidia and characteristic microconidia.

Infected hair does not fluoresce using Woodslamp.


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Tend to produce distinctive multicellular

macroconidia with echinulate walls .

Both types of conidia are borne singly in

these genera.


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These are chronic, localized infections of the

skin and subcutaneous tissue following the

traumatic implantation of the etiologic agent.

The causative fungi are all soil saprophytes of

regional epidemiology whose ability to adapt

to the tissue environment and elicit disease isextremely variable.



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Sporotrichosis

Sporothrix schenckii Rare

ChromoblastomycosisFonsecaea, Phialophora,

Cladosporium etc.Rare

Phaeohyphomycosis

Cladosporium, Exophiala,

Wangiella, Bipolaris,

Exserohilum, Curvularia

Rare

Mycotic mycetomaPseudallescheria, Madurella,

Acremonium, Exophiala etc.Rare


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Subcutaneous zygomycosis

(Entomophthoromycosis)

Basidiobolus ranarum

Conidiobolus coronatusRare

Subcutaneous zygomycosis

(Mucormycosis)

Rhizopus, Mucor, Rhizomucor,

Absidia, Saksenaeaetc.

Rare

Rhinosporidiosis Rhinosporidium seeberi Rare

Lobomycosis Loboa loboi Rare

clinical groupings for fungal infections

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