Superficial Fungal Infections

Dr.T.V.Rao MD

04/11/2023 Dr.T.V.Rao MD 1

SUPERFICIAL MYCOSES The superficial mycoses are usually confined to the outermost layer of skin, hair and do not invade living tissues.

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SUPERFICIAL MYCOSES

Pityriasis versicolor

Tinea nigraBlack piedra

White piedra

Keratomycosis04/11/2023 Dr.T.V.Rao MD 3

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PITYRIASIS VERSICOLOR(Tinea versicolor)

• Superficial chronic infection of Stratum corneum

• Etio: Malassezia furfur (Pityrosporum orbiculare) (Lipophilic yeast)

• Clinical findings: Hyperpigmented or depigmented maculae on chest, back, arms, abdomen

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Superficial• Do not elicit

immune response

• No discomfort • Cosmetic

problems• Limited to

stratum conium04/11/2023 Dr.T.V.Rao MD 6

Pityrisis versicolor

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Ring worm Infections• Infection of the Stratum corium.• Called as Dermatophytosis or

Tinea.• Called as per the site of Infection.• Tinea pedis – feet are involved.• Tinea captis – Scalp.

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RING WORM LESIONS

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Tinea lesions on Scalp

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Ring worm lesions on Face

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Severe nail infection with Trichophyton rubrum ina 37-year-old male AIDS patient.

Source: Intern. J. Dermatol. 31(1992): 453.04/11/2023 Dr.T.V.Rao MD 12

Dermatophytes,• There are 20 species of Dermatophytes

infect humans.• Classed under broad category.

1 Trichophyton,

2 Microsporum,

3 Epidermophyton

Infective particles -, a fragment of keratin,

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Common spp of Dermatophytes Infecting Humans

• T.rubrum• T.mentagrophytes• T.tonsurans• T.verucosom• Epidermophyton floccosum• Microsporum cannis

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Identification of Genus• Identified on the Basis of Macro

conidia.• Identification of species depends on

the disposition of Microcondia• Majority of Dermatophytes produce

1 Macro conidia and 2 Micro conidia.

In Epidermophyton Micro conidia are absent04/11/2023 Dr.T.V.Rao MD 15

FUNGAL DISEASES. Cutaneous mycoses: Fungal infections of the skin,

hair, and nails.

Secrete keratinase, an enzyme that degrades keratin.

Infection is transmitted by direct contact or contact

with infected hair (hair salon) or cells (nail files,

shower floors).

Examples:

– Ringworm (Tinea capitis and T. corporis)

– Athlete’s foot (Tinea pedis)

– Jock itch (Tinea cruris)04/11/2023 Dr.T.V.Rao MD 16

Cutaneous mycosesinvolves

• Skin• Hair• Nails• Evoke cellular immune

response• Dermatophytes• Clinical manifestations

ringworm or tinea04/11/2023 Dr.T.V.Rao MD 17

Cutaneous mycoses

Etiology

• Microsporum Trichophyton Epidermophyton

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Cutaneous mycoses• Classifications:

Anatomic location Tinea pedis Tinea capitis Tinea corporis Tinea cruris

Ecologic location Geophilic Zoophilic Anthrophilic

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Basic types of Dermatophytic infection:

1. The acute or inflammatory type of infection, which is associated with CMI to the fungus, generally heals spontaneously or responds nicely to treatment.2. The chronic or non-inflammatory types of infection, which is associated with a failure to express CMI to the fungus at the site of infection, is relapsing and responds poorly to treatment.

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Classification of Dermatophytes

• Trichophyton• Microsporoum• Epidermophyton

Differentiated on the Basis of Macrocondia,By Microscopy

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Cutaneous Mycosis

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Macroconida

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Macroconida

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Micro conidia

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Spread of Dermatophytes,• Spread of infection occurs through direct or indirect

contact.• Other ways of spread, From – Floors of swimming pools. Brushes,Combs,Towels,Predisposing factors Peeling of skin or minor traumaGenetic predisposition ?T Cell immunity is important,Phagocytes play a role.Invade Keratin ,Enzymatic, or Mechanical causes.

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Trichophyton• Colonies are powdery ,velvety,• Micro conidia are abundant,• Arranged in clusters,• Hyphae are borne on conidiophores• Special hyphal structures.• Infects

Skin, Hair, Nails,

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Microsporum• Colonies are cotton like,• Velvety or powdery,• Macroconida are scanty,• Macrocode are large ,Multicellular spindle

shaped,• Infects Hair, and Skin, Nails are not infected.

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Epidermophyton• Colonies are powdery

, greenish yellow,• Macroconida are

multicellular, pear shaped, typically arranged in clusters.

• Infects - Skin, Nails

But not Hair.

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General characteristics of Macroconida and Microconidia of Dermatophytes

Genus Macroconidia Microconidia

Microsporum Numerous, thick walled,rough

Rare

Epidermophyton Numerous, smooth walled

Absent

Trichophyton Rare,thin walled, smooth

Abundant

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Macroconida

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Pathogenesis• Depends on – site – species,• Only dry scaling• Hyperkeratosis,• Irritation, Erythema of skin,• Weeping pustules,• Ulceration,

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Clinical Presentation• Can produce Lesions on Body,face,scalp• Annular lesions ,raised,inflamatory

borders,• Groin lesions spread outwards from flexor

areas,• Toe clefts, sole• Nails get discolored, thickening, and

become friable.

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On scalp• Scaling Hair loss,• Hyphal break up to chains.• Endothrix –T.tonsurans,T.violaceum• Ectothrix - Microsporum,T.verucosum.• In Endothrix breaks at the mouth of follicle,

Black dot,• In Ectothrix breaks hair 2-3 mm from mouth of

the follicle.• Mixed infections do occur.

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The Hair may show Endothrix or Exothrix

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Cutaneous mycoses• THE IDENTIFICATION REACTION(ID)

• Patients infected with a dermatophytes may show a lesion, often on the hands, from which no fungi can be recovered or demonstrated.

• It is believed that these lesions, which often occur on the dominant hand (i.e. right-handed or left-handed), are secondary to immunological sensitization to a primary (and often unnoticed) infection located somewhere else (e.g. feet).

• These secondary lesions will not respond to topical treatment but will resolve if the primary infection is successfully treated.

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Clinical Manifestations• Appear as scaly

lesion • Upper trunk, neck• May be Hypo

pigmented and Hyper pigmented

• Spread to other sites of the body

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Laboratory Diagnosis• Direct

Microscopy,• Demonstration of

clusters of round yeast cells

• Short and stout hyphae,

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Id reaction• Inflammation

associated with infection with fungi

• An immunological reaction to fungal infection

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Laboratory Diagnosis

• Collection of samples,• Specimens of skin, hair, nails• Collected in folded black paper,• Stored up to 12 months,• Nails by clippings,• Skin by scrapping with blunt scalpel,• Hair by plucking

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Microscopy,• Direct Microscopy with wet mount

preparation with 15-20% Potassium hydroxide (Koh) preparation

• Examination under fluorescent Microscope with Calcoflour

• Examination under Woods lamp04/11/2023 Dr.T.V.Rao MD 41

Examination under Wood’ Lamp

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Culturing of Dermatophytes

• Small fragments of Keratinous material used for culturing on

• Sabouraud's agar,• 4 % Malt extract agar,• Colony morphology and color

pigmentation observed.• Microscopic observation

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Treatment and Prevention,

• Topical therapy• Application of

Topical Azoles ,compound Terbinafin,oral Grisofulvin,

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Treatment

• Pityriasis responds to Topical therapy,

• 1% Seliniumsulphide,• Azoles – Ketoconazole.• Oral Azoles,

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Treatment• Skin – azoles,inhibits cytochrome

450 dependent enzyme systems at the demethylation step from lanosterol to ergosterol

• Hair- Griseofulvin, oral , affects micro tubular system

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Other Fungal Infections of Skin

• Pityriasis Versicolor ,Belong to Genus Malassezia

• Infection of stratum corneum• Manifest as patches of discoloration of

skin,• Caused by lipophilic yeast• Depends on Host and Environments,• Tropical countries- Young adults,

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Morphology

• Produce round yeast cells,

• Short hyphae• Appear as

Gram Positive04/11/2023 Dr.T.V.Rao MD 48

Candidiasis can Present as Skin Lesions

• Candidiasis , Monoliasis,

• Can infect Skin, Mucosa, or Internal Organs,,

• Called as Yeast Like fungus

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Candida and other species,

• Candida albicans,• Others spp

C.tropicalis,

C.Krusei,

C.glabrata,

C.parapsilosis,

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Candida • Common flora

Exist in Mouth, Gastrointestinal tract.

Vagina, skin in 20 % of normal

Individuals.

Colonization increases with age, in pregnancy

Hospitalization

Immunity Depends on T lymphocytes, and Europhiles

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Morphology and Culturing

• Ovoid shape or spherical budding cells and produces pseudo mycelium

• Routine cultures are done Sabroud’s Glucose agar,

• Grow predominantly in yeast phase• A mixture of yeast cells and pseudo

mycelium and true mycelium are seen in Vivo and Nutritionally poor media.

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Pseudohypal structures in Candida

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Pathogenesis and Pathology

• Mucosal infection superficially –Discrete white patches on mucosal surface.

• Can affect tongue • Infants and old persons are affected • Immune compromised /AIDS. Oral Candidiasis

is commonly seen• Vaginal Candidiasis causes itching soreness

white discharge, White colored lesions,• Pregnancy with advance,• One episode through life time

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Other lesions• Esophageal infection common in HIV /

AIDS• Skin – Nail infections• Axilla Groin• Toe clefts,• Napkin dermatitis,• Nails frequent immersion in water House wives, Washer man Nurses,

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Predisposing factors.

• Infancy, old age, Pregnancy,

• Change of flora.• Moisture, occlusion

Trauma• T Lymphocyte

disease. Neutropenia.• Diabetes mellitus

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Location of Infections

• Localized and Disseminated.

• Multi organ involvement.

• Kidney,Liver,Spleen, Brain.GIT.Eye,

• Catheter related infections,

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Other lesions

• Chronic muco coetaneous Candidiasis

• In childhood –suspect defects of Lymphocytes and Neutrophils,

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Laboratory Diagnosis

• Skin scrapings,• Mucosal scrapping,• Vaginal secretion• Culturing Blood and other body fluids,• Observations

Microscopic observation after Gram staining. Gram + yeast cells.

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Cutaneous mycoses

• Laboratory diagnosis: scrapings from clinical specimens

• Hair – endothrix (spores inside the hair shaft -ectothrix -exception: T.schoenleinii

Disease-favus-waxy mass of hyphal elements (scutulum) microscopic –degenerated hyphal elements

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Cutaneous mycoses• Cultures• Selective media – containing

Cyclohexamide and chlorampenicolincubate at 25 C.

• Identification based on the conidia

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Diagnosis• Diagnosis is based upon:

1. Anatomical site infected

2. Type of lesion

3. Examination with a Woods lamp (366 A°)

4. Examination of KOH-treated skin scales from the infected area

5. Culture of the organism (not too important)

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Diagnosis of Deep seated infections

• Difficult to culture,

• Alternative methods

• Antibody titers,• ELISA testing• CIE04/11/2023 Dr.T.V.Rao MD 63

Culturing

• Sabouraud's Medium or Blood agar• Yeast colonies appear within 1-2 days• Germ tube test - Incubation of colonies in

serum at 37 c from 1.5 to 2 hours produce• Short hyphae known as germ tube• Candida albicans are Germ tube

producers• Other tests are – Sugar assimilation and

fermentation tests.04/11/2023 Dr.T.V.Rao MD 64

Germ Tube TestC.albicans

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Germ Tube TestC.albicans

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Treatment• Skin

removal of the organism by: 1.Selenium sulfide 2.Thiosulfate 3.Salicylic acid 4.Hyposulfite inhibition of ergosterol by: 1.miconazole

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Treatment with Modern Drugs

• Nystatin,• Amphotericin B• Miconazole,• Topical Imidazole application• Systemic infection needs

Intravenous – Amphotericin B

Intravenous or Fluconazole.

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Differential diagnosis• In a differential diagnosis you must consider:

1.     Leprosy 2.     Secondary syphilis 3.     Pityriasis rosea      

   4.     Psoriasis         5.     Nummular eczema          6.     Lichen planus         7.     Alopecia areata         8.     Trichotillomania         9.     Dyshidrosis     10.     Contact dermatitis.

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