Mycology Lec2superficial

MICROBIOLOGY LECTURE M2 – Superficial Mycoses Lecture and Notes by Dr. Ng USTMED ’07 Sec C – AsM

some perifollicular patches are evident on the upper abdomen. (A)

SUPERFICIAL MYCOSES

Hyperpigmented Tinea Versicolor Perifollicular round patches of hyperpigmented lesions are tightly grouped on the upper back. (B)

INFECTIONS DUE TO Malassezia Species

3 Species of Medical Importance • Malassezia furfur • Malassezia pachydermatis • Malassezia sympodialis MALASSEZIA FURFUR

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Hyperpigmented Tinea Versicolor The fine, branny scaling is not readily evident until lesions are gently scraped with the end of a glass microscope slide. (C)

causes Pityriasis versicolor – a chronic, usually asymptomatic fungal infection of the stratum corneum synonyms for Pityriasis versicolor - tinea versicolor, tinea flava, dermatomycosis furfuracea, “liver spots” member of the normal skin flora

HISTORY

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1846 - detected by Eichstedt & named the disease pityriasis versicolor 1853 - Robin named the fungus Microsporon furfur

Inflammatory Versicolor

Tinea

1874 - Malassez described the yeast-like cells from lesions of the scalp 1889 - Baillon created genus Malassezia 1939 - Benham described the lipophilic nature of the fungus

EPIDEMIOLOGY

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worldwide distribution but more prevalent in the tropics & subtropics some countries - 50% of people are infected occurs in both sexes, all ages, all races major factor - excessive sweating other factors - poor hygiene, malnutrition, poor health, pregnancy, systemic steroids, Cushing’s syndrome

CLINICAL MANIFESTATIONS

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Folliculitis uncommon variant - lesions resemble acne - papules & pustules history of antibiotic or steroid intake - may resolve spontaneously or evolve into abscesses Sepsis -

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Pityriasis versicolor Folliculitis Sepsis other conditions o Peritonitis o Nipple discharge o Dacryoliths o Sinusitis

catheter-acquired neonates & adults on prolonged IV lipid hyperalimentation peripheral blood is usually negative usual source - patient’s skin or medical personnel other conditions

Other Conditions -

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Pityriasis versicolor - usually: asymtomatic, hyperpigmented macules or patches - common sites - chest, upper back, shoulder, upper arms, abdomen may extend to - thighs, neck, forearms rare in - scalp, palms, feet - hair shafts & nails - not infected - color varies according to : (1) pigmentation (2) exposure to sunlight (3) severity CLINICAL PRESENTATION OF PITYRIASIS VERSICOLOR

peritonitis nipple discharge dacryoliths sinusitis

DIAGNOSIS

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Direct Examination o KOH mount - short, angular, occasionally branching, septate hyphae & clusters of budding yeast o Wood’s light - most lesions fluoresce yellow Skin scrapings stained with periodic-acid schiff’s stain showing typical yeast-like and hyphal fragments of Malassezia furfur, the etiology agent of Pityriasis Versicolor

KOH wet mount of Tinea Versicolor Abundant short hyphae and round spores, so-called Spaghetti and meatballs are apparent. (A)

Hyperpigmented Tinea Versicolor Round, hyperpigmented, barely palpable plaques and

Adding a small amount of Parker’s blue-black ink to the KOH stains Pityrosporon organisms blue and facilitates their identification from the skin scrapings.

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Culture

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often not necessary, tedious & meticulous Sabouraud’s agar with antibiotics at 37C overlay with olive oil or whole-fat milk colonies appear dry, smooth or lightly wrinkled, glistening or dull, white to creamy

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in man - associated with psoriasis or mycosis fungoides, febrile systemic syndrome (neonates)... isolated from urine, CSF, blood, vaginal, eye & ear discharge, tracheal aspirate also reported in patients receiving IV lipid hyperalimentation (esp. neonates) grows on agar at 37C without the addition of oil

MALASSEZIA SYMPODIALIS

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isolated from the scalp of an AIDS patient with tinea capitis (1990)

PIEDRA (Black & White) DEFINITIONS

• • Gram stain and calcofluor white preparation of Malassezia furfur

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a chronic, fungal infection of the hair shaft, forming firm, irregular nodules or encrustations composed of fungal elements 2 varieties - black & white, produced by 2 different species synonyms - tinea nodosa, trichomycosis nodularis, trichomycosis nodosa, Beigel’s disease, Chignon disease

ETIOLOGY

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Black Piedra - Piedraia hortai White Piedra - Trichosporon beigelii Hair infected wth Piedraia hortae. The hard black nodule contains asci and ascospores, the sexual phase of the fungus.

Clinical presentation white piedra

DIFFERENTIAL DIAGNOSIS

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steroid-induced acne acne vulgaris vitiligo

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pigmentary disorders eg. Chloasma inflammatory conditions eg. tinea circinata, seborrheic dermatitis, pityriasis rosea, erythrasma, syphilis, pinta

BLACK PIEDRA Piedraia hortai on hair

IMMUNOLOGY

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rare in children under 10 years, associated with increase sebaceous gland activity sweating - predisposing factor genetics - may play a role

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antibodies - detectable in chronic cases indirect IF - organism in skin scales & culture

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PATHOLOGY

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limited to the stratum corneum moderate hyperkeratosis may be seen

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increase in melanosome size but not in number other changes - mild acanthosis & perivascular lymphocytic infiltrate

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TREATMENT

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selenium sulfide Na thiosulfate salicylic acid benzoyl peroxide the azole family eg. Ketoconazole NB. recurrence rate - very high despite treatment

MALASSEZIA PACHYDERMATIS

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first isolated in 1925 from Indian rhinoceros often associated with otitis externa of dogs

of

HISTORY

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1865 - Beigel first observed white piedra 1901 - Malgoi-Hoes described black piedra 1911 - Horta differentiated black from white piedra 1928 - Fonseca & Leao named the etiology of black piedra, Piedraia hortai 1936 - Langeron summarized findings on both varieties

EPIDEMIOLOGY – BLACK PIEDRA

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tropics & subtropics males = females

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common among regular swimmers

EPIDEMIOLOGY – WHITE PIEDRA

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more common in the temperate zone affects both sexes of all age group lower incidence than black variety

CLINICAL MANIFESTATION – BLACK PIEDRA

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usually on scalp hair only

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infected hair - rough, sandy or granular

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nodules - hard, fusiform, firmly attached to hair shaft

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thick part - layers of fungal cells cemented thin part - single layer of cells & hyphae does not penetrate cortex of hair hair follicles not involved

CLINICAL MANIFESTATION – WHITE PIEDRA

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usually on facial & genital hair nodules are softer, mucilaginous, white to light brown in color nodules are not as adherent hair follicles not affected

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DIFFERENTIAL DIAGNOSIS

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pediculosis (pubic hair)

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trichomycosis axillaries o Gram stain - cocci & short bacilli o UV light - (+) fluorescence o due to Corynebacterium tenuis nits & lice tinea capitis

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TREATMENT – BLACK & WHITE

DEFINITION

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Direct Examination] o KOH mount – Black Piedra

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nodules are composed of tightly packed, regularly arranged, thickwalled cells

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dichotomously dematiaceous hyphae

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central part - fungal cells cemented

branching,

periphery - aligned hyphal strands asci are found within the locules containing up to 8 ascospores KOH mount – White Piedra 

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nodules are softer, less adherent, not as discrete often - transparent, greenish, rregular sheath cells are not as organized one sees only blastospores arthrospores

Culture - Piedraia hortai

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grows slowly on Sabouraud’s agar (24wk) at 25-30C

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some colonies : reddish-brown, diffusable pigment on agar

examination dematiaceous, septate, branching hyphae with asci & ascospores Culture - Trichosporon beigelii

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grows moderately on Sabouraud’s agar (1-2 weeks) at 25-30C

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colonies appear smooth, highlywrinkled or radially folded, yeastlike, cream-colored

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Cladosporium werneckii or Exophiala werneckii

HISTORY

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ETIOLOGY

compact, dark-brown to black, conical colonies with short aerial hyphae

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a chronic, superficial, usually asymtomatic, fungal Infection usually of the palms synonyms keratomycosis nigricans palmaris, cladosporiosis epidermica, pityriasis nigra, microsporis nigra primary medical importance - often misdiagnosed as melanoma

1891 - first observed in Brazil by Cerqueira 1916 - Cerqueira-Pinto reported his own observation & his father’s 1921 - Ramos e Silva reported first case in Rio de Janeiro; Horta isolated a fungus from the same patient: Cladosporium werneckii 1970 - von Arx transferred the genus to Exophiala

EPIDEMIOLOGY

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Culture

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topical medication in lotion

TINEA NIGRA

LABORATORY DIAGNOSIS

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shaving affected area or cutting infected hair

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considered a tropical disease but extends to the temperate zone (esp. WH) occurs in any age group but more common under 20 male:female (1:3) no known predisposing factor although many are hyperhydrotic transmission not known to occur

patients

CLINICAL MANIFESTATION

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usually asymptomatic lesion - usually, a dark patch on the palm of one hand with well-defined, irregular margin about 1-5 cm in diameter other locations - sole of foot, interdigits, wrists, forearm, trunk, neck no induration, no erythema, and has the characteristic “stained appearance” ocassionally - pruritus & scaling

examination - hyaline, septate hyphae with many arthrospores

TINEA NIGRA: Dark pigmentation in the center of palm

TINEA NIGRA: Dark pigmentation in the center of palm

ETIOLOGIC AGENTS

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TINEA NIGRA: Dark pigmentation in the center of palm

Histoplasma capsulatum Fusarium solani

EPIDEMIOLOGY

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More often in males and individual below the age of 50 years.

CLINICAL MANIFESTATIONS

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Raised cornea ulcers with occassional satellite lesions, plaques or hypopyon

DIAGNOSIS

• DIFFERENTIAL DIAGNOSIS

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melanoma junctional nevus contact dermatitis pigmentation of Addison’s disease post-inflammatory melanosis syphilis pinta staining from chemicals

Direct examination (demonstration of hyphae) o corneal scrapings o Surgical specimens Culture o Fusarium species grow rapidly in:  Sabourauds medium  Enriched medium Fusarium spp. Colony on potato dextrose agar. The colonies appear to be cottonlike, usually white, turning pink-violet or brown at the center with age

PATHOLOGY

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confined to the upper layers of the stratum corneum mild hyperkeratosis may be seen pigmentation is due to the fungus

Fusarium spp. Stained with lactophenol cotton blue. Typical Fusarium spp: Microconidia with a fusiform or oval shape extending from delicate lateral phialides. Macroconidia are fusiform, usually curved, giving the appearance of a sickle and have three to five septae.

TINEA NIGRA: Hematoxylin-eosin-stained section of palmar skin Show abundant dark-colored fungal elements. LABORATORY DIAGNOSIS

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Direct Examination o KOH mount - long, sinuous, strongly dematiaceous branching, septate hyphae & elongated budding cells

-finauds [email protected] [email protected]

Yeastlike cells of Exophiala werneckii, the causative agent of tinia nigra

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Culture

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Sabouraud’s agar with antibiotics at 25-30C colonies appear shiny, moist, yeastlike, dirty white to brown, covered with masses of conidia & budding cells will turn black in 2-3 weeks

TREATMENT

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sulfur salicylic acid Na thiosulfate the azoles eg. Ketoconazole NB. recurrence rate – low

MYCOTIC KERATITIS (KERATOMYCOSIS)

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FUNGAL INFECTIONS OF THE CORNEA o cause: History of trauma leading to the inoculum of eyes with a fungus