Superfical and Cutaneous

7/27/2019 Superfical and Cutaneous

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Superficial andCutaneous Mycoses


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Outline of presentation

Objective

General information about mycoses

Superficial mycoses Black piedra

White piedra

Tinea nigra

Pityriasis

Cutaneous mycoses


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Objective

At the end of this chapter, the student will be able to: List commonly known superficial and cutaneous

mycoses

List the etiological agents, epidemiology,pathogenesis and clinical picture, and laboratorydiagnostic techniques applied for these fungalinfections.

Describe the laboratory diagnostic features todifferentiate the etiological agent which causessuperficial and cutaneous mycoses.


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Mycoses

Dermatomycoses

Superficial mycoses

Cutaneous mycoses

Subcutaneous mycoses

Systemic mycoses

Primer systemic mycoses

Opportunistic mycoses

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Superficial mycoses Development of fungal infection on epithelial

tissue skin, hair nail without noticeable invasion

of living tissue

Growth on human body may be coincidental

Mammalian body may be the natural habitat of

fungus

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Superficial infection

Black piedra

White piedra

Tinea nigra

Pityriasis

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Black piedra

Affecting hair primarily scalp

Etiology Piedraia hortae

Dematiaceous filamentous fungus found in soil

Particularly at humid tropical areas

Classified in Ascomycetes

Characterized by formation of brown to blacknodules that are very firmly attached to the hair shaft

Nodules can not be pulled out of the hair shaft

It is though to be a condition of poor hygiene

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Black piedra Contd

Microscopically

Septate hyphae, ascostromata, asci, and

ascospores are visualized

Hyphae darkly pigmented

Cultures on routine mycology media

Colonies slow growing, small, folded, velvety

and dark brown to black in color

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Black piedra Contd

Treatment

Hair cut and proper regular washing

Topical salycylic acid, azole creams

Oral ketoconazole or terbinafine may also be used

Relapses may occur even after appropriate

management of the infection with antifungal agents

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White piedra

Localized to the hair of groin and axillae or scalp

But may also be seen on facial hairs and sometimespubic hair

Fungus surround the hair shaft and form a white to

brown swelling along the hair

Etiology

Trichosporon spp (T. inkin, T. ashii, T.beigelii,T.mucoides)

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Etiology contd

Have multilamelar cell wall; develop

dolopores

Hyphae elements have arthroconidia

Classified in basidiomycetes

Form cubic or rectangular arthroconidia

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White piedra Contd

As an opportunistic fungal pathogen

Immunocompromised hosts

Frequent in tropical and temperate zone

Common in young adults

Clinical presentation

Asymptomatic fungal growth on the outside of the hair shaft

Soft, white to yellow nodules, loosely attached to the hair

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White piedra Contd

Macroscopic Features Culture SDA (without cycloheximide)

Colonies yeast-like

Rapid growing, smooth,

Wrinkled, raised, folded,, waxy, white, or yellowish white tocream color

Microscopic Features

Abundant and well-developed pseudohyphae and hyphae Blastoconidia are unicellular and variable in shape

Typical microscopic feature production of arthroconidia

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White piedra Contd

Treatment

Shaving the hairs is the simplest method of

treatment

Topical application of an imidazole agent may be

used to prevent re-infection

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Tinea nigra

A superficial chronic infection of Stratum corneum

Usually occur on the palmar aspects of hands andoccasionally the plantar and other surfaces of the skin

Etiology Hortaea (Exophiala, phaeoannellomyces) werneckii

Ascomycetes

A common saprophytic fungus believed to occur :-

In soil, compost, Humus and on wood in humid tropical and sub-tropical

regions

Dematiaceous fungi frequently branched septate

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Tinea nigra contd

Distribution

World-wide More common in tropical regions of Central and South

America, Africa, South-East Asia and Australia

Clinical manifestations

Skin lesions characterized by brown to blackmacules

Usually occur on the palmar aspects of hands andoccasionally the plantar and other surfaces of the skin

Lesions are non-inflammatory and non-scaling

Familial spread of infection has also been reported16


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Tinea nigra contd

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Tinea nigra contdLaboratory diagnosis

Clinical Material: Skin scrapings

Culture oatmeal agar: growth restricted smooth andslimy with an oily glistening black color

On SDA colonies

Initially mucoid yeast like and shiny black

With age develop abundant aerial mycelia and becomedark olivaceous in color

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Tinea nigra contd

Direct Microscopy

Skin scrapings should be examined using 10% KOHand Parker ink or calcofluor white mounts

Dematiceous multibracnhed septate hyhae and buddingyeast cells

Typical 2-celled, pale brown yeast cells, with prominentdarkly pigmented septa, which act as annellided

Annelids may also arise from the hyphae

Annelloconidia are 1to 2 celled cylinderical to spindle shapedhyaline

To pale brown and usually occur in aggregate masses

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Calcofluor white Stain of skin scrapping

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Tinea nigra contd

Treatment

Topical therapy

Whitefields ointment

Azole creams

Terbinafine

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Malassezia infectionsMalassezia furfur

A dimorphic, lipophilic yeast

Normally resident on human skin in the sebum-rich areas ofthe upper trunk and head

Pityriasis versicolor

A chronic, superficial fungal disease of the skin

characterized by well-demarcated white, pink, fawn, orbrownish

Discrete serpentine hyper or hypo pigmented maculaeoccur on the skin usually on chest, upper back, arm orabdomen

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Pityriasis versicolor Contd

Lesions, often coalescing, and covered with thin

furfuraceous scales

The colour 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

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Pityriasis versicolor showing hyperpigmented and

hyphopigmented


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Pityriasis folliculitis

Pityriasis folliculitis

Characterized by follicular papules and pustules

Localized to the back, chest and upper arms,

sometimes the neck, and more seldom the face

Itchy and often appear after sun exposure

Scrapings or biopsy specimens show numerous

yeasts occluding the mouths of the infected follicules

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Malassezia infections contd

Seborrhoeic dermatitis and dandruff

Dandruff being the mildest manifestation

Seborrhoeic dermatitis characterized by

Rash consisting of yellow brown greasy scales, witha distinctive distribution over

The scalp, face,

Interscapular and presternal areas

Clinical manifestations Erythema and scaling in areas with a rich supply of

sebaceousglands, the scalp, face, eyebrows

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Multifactorial host factors predispose to

seborrhoeic dermatitis Genetic predisposition

Emotional component (possible endocrine or

neurologically mediated factors)

Changes in quantity and composition of sebum

Increase in alkalinity of skin (due to sweating)

External local factors such as occlusion

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Fungaemia

Causing catheter acquired in neonate and adult

patients undergoing lipid replacement therapy

Patients may also develop small embolic lesions in

the lungs or other organs

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Diagnosis

Direct microscopic examination of scrapping ofinfected skin treated with 10-20% KOH

Stain with

Calcofluor white

Hematoxtline and

Eosine (H&E)

Period Acid Schiff (PAS)

Short unbranched hyphae and spherical cells areobserved

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PAS of skin scraping


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Growth ofMalussezia yeast after 7 days of

incubation at 32oC.

Malassezia yeasts microscopic

examination


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Treatment

Topical azoles and selenium sulfide shampoo

For widespread infection oral Ketoconazole oritraconazole

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Cutaneous mycoses

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Cutaneous mycoses Affect superficial keratinized tissue (skin hair and

nail)

Dermatophytes important etiologic agent

The disease referred deramatophytosis

A complex of disease caused by any of several species oftaxonomically related filamentous fungus

Trichophyton,

Epidemophyton

Microsporum

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Cutaneous mycoses contd

Dermatophytes

Geophilic

Zoophilic

Anthrophilic

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Disease process in dermatophytosis unique

Invaded the keratinisedtissue (stratum corneum) Ketatinophilic and ketatinolytic

Metabolic products usually induces an allergic and

inflammatory eczematous response in the host

Various forms of dermatophytes referred as tinea or

ringworm

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Tinea

Tinea capitis of scalp eyebrows and eyelashes

Tinea barbae of beard

Tinea corporis of the smooth or glabrous skin

Tinea cruis of groin

Tinea pedis of the foot

Tinea unguium of the nails36


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Ecology of Common Human Dermatophyte Species

Species Natural habitat Incidence

Epidermophyton f loccosu m Humans Common

Tr ichophyton rubrum Humans Very Common

Tr ichophyton interdigi ta le Humans Very Common

Tr ichophyton tonsurans Humans Common

Tr ichophyton v iolaceum Humans Less Common

Tr ichophyton concent r icum Humans Rare*

Tr ichophyton sch oenleinii Humans Rare*

Tr ichophyton soudanense Humans Rare*

Microsporum audouini i Humans Less Common*

Microsporum ferrugineum Humans Less Common*

Tr ichophyton mentagrophytes Mice, rodents Common

Tr ichophyton equinum Horses Rare

Tr ichophyton er inacei Hedgehogs Rare*Tr ichophyton verrucosum Cattle Rare

Microsporum canis Cats Common

Microsporum gypseum Soil Common

Microsporum nanum Soil/Pigs Rare

Microsporum cookei Soil Rare

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Dermatophytes infection begins in the skin after traumaand contact

Susceptibility may be enhanced by moisture warmth

Factors Chemistry of skin,

Compostion of sebum

Perspiration

Heavy exposure

Genetic predisposition

Higher in hot humid climate

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Clinical manifestations

Affected by factors such as

The species of dermatophytes

The inoculum size

The size of infection

The immune status

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Tinea pedis (Athlelets Foot)

Infection of the toe webs

Vesicular ulcerative and moccasin types, withhypherkeratosis of the sole

Infections by anthropophilic dermatophytes Trichophyton rubrum, Trichophyton mentagrophytes, and

Epidermophyton floccosum.

Caused by the shedding of skin scales containing

viable infectious hyphal elements [arthroconidia]

Transmission may take place by indirect contact

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Tinea pedis in toe foot pad

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Cutaneous mycoses contdTinea Manuum

Infection of the hands

Causative agent T. rubrum

less common than tinea pedis

Like tinea pedis

Presents with the classic pattern of erythema and mild scalingon the dorsal aspect of the hands

or as a chronic, dry, scaly hyperkeratosis of the palms

When the palms are infected, the feet are also commonlyinfected

A typical pattern of involvement is either one hand and bothfeet or both hands and one foot.


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Tinea cruris

E. floccosumand T. rubrum

Dermatophytosis of

The proximal medial thighs,

preum and buttocks

Occurs more commonly in males

Due to spread of the fungus from the feet

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Tinea unguium (dermatophyte onychomycosis)

Etiology Trichophyton rubrum and T. interdigitale

superficial white onychomycosis

Invasive, subungual

Distal subungual onychomycosis the most common

Yellowish-white spots which slowly invade the ungula

and then the nail plate

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Tinea of the nails caused by T. rubrum

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Tinea barbae Trichophyton verrucosum Rare infection

Infection exclusively in males

Limited to the bearded

Develop without characteristic

lesions

Always with pruritus

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Tinea corporis Affect glabrous skin

Anthrophophilic species

T. rubrum T. tonsurans

T. verrucosum

GeophilicM. gypseum

zoophilic speciesM. canis

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Tinea capitis

Trichophyton and Microsporum

Most common in pediatric

Dermatophytosis of the scalp

Ectothrix

Endothrix

Favus hyphae without spores throughout hair length

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Laboratory diagnosisMicroscopy

Direct mount,10% potassium hydroxide (10% KOH)

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Isolation and identification

Sabourauds dextrose agar containing

cycloheximide (actidione) and antibiotics

incubated at 26-28oC 2-4 weeks

Identification of the species primarily on the

conidia that produced

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Treatment and Management

Dependent on the clinical setting

Topical or systemic antifungal Agent

Removal of infected and dead epithelial structure

Surgical removal of the nail

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Superfical and Cutaneous

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