Fungal Infections Of The Skin Flashcards

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1
Q

What is the definition of a fungi?

A

Aerobic organisms that form a cell wall and grow on or in organic material, forming a colony and reproducing either sexually or asexually

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2
Q

What are the 2 classes of fungi?

A

Dermatophytes
Yeasts

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3
Q

What are the 3 subclasses of dermatophytes?

A

Tricophyton
Microsporum
Epidermophyton

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4
Q

What are the 2 subclasses of yeasts?

A

Candida albicans
Malasezia furfur

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5
Q

What are the 3 types of superficial fungal infections?

A

Candida species
Malassezia species
Dermatophytes

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6
Q

How do superficial fungal infections form?

A

Capable of colonising (cutaneous microbiome) and superficially invading skin and mucosal sites

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7
Q

When do deeper, chronic cutaneous fungal infections occur?

A

After percutaneous inoculation

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8
Q

what are some examples of deeper, chronic fungal infections?

A

Phaeohyphomycosis, sporotrichosis

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9
Q

When do systemic fungal infections occur?

A

Most often with host defence defects. Primary lung infection disseminates hematogenously to multiple organs systems including the skin

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10
Q

What ids the aetiology of fungal infections?

A

Nature of fungus
Human host age, gender and race
Immune status of host
Contributing factors - macearation, occlusion, minor skin trauma

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11
Q

What is the diagnostic approach for fungal infections?

A

Clinical diagnosis
• Microscopic examination (KOH examination)
• Culture
• Wood light examination (UV light–365nm)
• Skin biopsy
• Trichophytin test
• PCR
• ELISA

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12
Q

What is the clinical presentation of Dermatophytes?

A

Infection of skin, hair and nails caused by dermatophytes (fungi that live within the epidermal keratin or hair follicle and do not penetrate into deeper structures)

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13
Q

What is the pathophysiology of Dermatophytes?

A

Digestion of keratin by Dermatophytes results in scaly skin, broken hairs, crumbling nails

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14
Q

Which investigations are useful for Dermatophytes?

A

Skin scrapings
Hair and or nail clippings analysed with potassium hydroxide prep to look for hyphae and mycelia

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15
Q

What are the different types of dermatotyphoses?

A

Tinea Capitis
• Tinea Barbae
• Tinea Faciei
• Tinea Corporis
• Tinea Cruris (inguinalis)
• Tinea Manus
• Tinea Pedis
• Tinea Unguium (Onychomycosis)

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16
Q

What are the clinical features of tinia capitis?

A

Area of erythema and scale with local hair loss
Border is usually sharply defined and inflammed

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17
Q

What is Kerion Celsi? (Caused by tinea capitis)

A

Massive destruction of follicles, producing a boggy nodule with pustules, sinus tracts and drainage

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18
Q

What is the diagnostic approach for tinia capitis and Kerion celsi?

A

Potassium hydroxide examination of scales or plucked hairs, as well as cultures

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19
Q

What will the examination show for most microsporum?

A

Greenish fluorescence with a wood light

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20
Q

What are the clinical findings for tinea favosa? (Most severe form of tinea capitis)

A

Children are mostly affected
Mild forms - erythema and loss of hair luster
As disease progresses - erythema and typical scutula (compact accumulations of yellow scales and crusts) appear which leads to scarring
Most intense cases - extensive scarring alopecia with peripheral active disease and unpleasant odour

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21
Q

What is the treatment for tinea capitis?

A

Fluconazole 6mg/kg/day for 3 weeks
Itraconazole - 5mg/kg/day for 4 weeks
Terbinafine - 125mg/day (25kg weight), 187.5mg/day (25-35kg weight), 250mg/day (>35kg weight) for 6 weeks
Griseofulvin 20-25mg/kg/day for 6-8 weeks (up to 16 weeks)

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22
Q

What is tinea Barbae?

A

Disease of men and almost always occurs in farmers, vets, and other exposure to large animals

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23
Q

What are the clinical findings of tinea barbae?

A

Severe, deep folliculitis with erythema, modular infiltrates, scales and pustules
Deep furunculoid nodules, still coated with pustules develop

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24
Q

what is the rule for tinea barbae?

A

Marked regional lymphadenopathy

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25
Q

What typically happens to tinea barbae after 4-6 weeks?

A

Spontaneous resolution with immunity

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26
Q

What is the diagnosis for tinea barbae?

A

Epilated hairs in potassium hydroxide examination and culture

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27
Q

What is the most likely cause of tinea faciei? (Ringworm)

A

Patients who sleep in very close contact with their pets, especially small children and women

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28
Q

Which pets are the biggest carriers of tinea faciei?

A

Cats and dogs

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29
Q

Which fungi produces tinea faciei?

A

Zoophilic fungi

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30
Q

What is the clinical manifestation of tinea faciei?

A

Annular or serpiginous lesions (wavy margins)

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31
Q

Which dermatophytes can cause tinea corporis?

A

Almost all dermatophytes

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32
Q

What is the clinical manifestation of tinea corporis?

A

Lesions which are sharply bordered, peripherally spreading, slightly indurated (hardened) patch or plaque
Border is often redder with prominent scale and pustules
Scales are usually at the leading edge, pointing towards normal skin
Older, central lesions typically resolve as periphery advances

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33
Q

Are men or women more likely to be infected by tinea cruris?

A

Men far more likely

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34
Q

What should one check if they also have tinea pedis?

A

Check the feet of all patients with groin rashes

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35
Q

What are some risk factors for tinea cruris?

A

Obesity
Inadequate personal hygiene
Hyperhydrosis
Prolonged sitting on plastic or non absorbent surfaces
Tight synthetic clothing
Diabetes mellitus

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36
Q

What is the clinical manifestation of tinea cruris?

A

Slowly spreading erythematous patches with scaly borders most often found on upper inner aspects of thigh, where scrotum touches leg
Occasionally disease spreads to scrotum, perineum, perianal area, and gluteal cleft

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37
Q

What is another name for tinea pedis?

A

Athletes foot

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38
Q

Which climates is tinea pedis more common in?

A

Warmer, moister climates

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39
Q

How is tinea pedis caught?

A

The spores of the dermatophytes survive for months in shoes, carpets, bath mats, locker rooms and showers

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40
Q

What are risk factors for tinea pedis?

A

Reduced hygiene
Advanced age
Hyperhydrosis
Warm and moist environment
Impaired peripheral blood flow

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41
Q

What are some preventative measures for tinea pedis?

A

Using rubber sandals in community showers
Carefully drying feet especially between toes
Wearing clean socks and shoes

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42
Q

What are the 3 types of tines pedis?

A

Interdigital
Hyperkeratotic
Dyshydrotic

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43
Q

Where is tinea pedis the interdigital type commonly found?

A

Predominantly in the lateral 2 toe webs due to being the tightest interdigital spaces
Will find grey white swollen skin between the toes
When the macerated skin is removed, erosions, fissures and erythema may be prominent
Process often extends to the sole

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44
Q

What are the 3 aggregating factors in the interdigital type?

A

Hyperhydrosis
Gram negative toe web infections

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45
Q

What almost always causes the hyper keratotic or moccasin type of tinea pedis?

A

T. Rubrum and usually accompanied by tinea unguium

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46
Q

What are the clinical features of the hyperkeratotic type of tinea pedis?

A

Thick scales, tropic all covering the heels, the tips of the toes and metacarpal pads

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47
Q

What can be seen upon closer examination of hyperkeratotic tinea pedis?

A

Erythema at the advancing border may be seen

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48
Q

Will both or one foot typically be involved in hyper keratotic tine pedis?

A

Just one foot occasionally (as opposed to palmoplantar keratoderma which is bilateral and does not have nail involvement)

49
Q

How does the diastase progress for dyshydrotic type of tinea pedis?

A

Asymptomatic for long intervals then experience sudden eruption of pruritic grouped vesicles, usually on the instep

50
Q

What is the appearance of the vesicles in dyshydrotic type?

A

Cloudy and purulent and may coalesce, forming large fluid filled blisters that eventually shed their rood, eroding with scale and erythema at the edge

51
Q

How do you diagnose the dyshydrotic type?

A

Using potassium hydroxide

52
Q

Is tinea pedis a chronic or acute problem?

A

Chronic

53
Q

Which form of tinea pedis is recurrent?

A

Dyshydrotic form

54
Q

What are some complicastions of tinea pedis?

A

Fungal reactions
Gram negative toe web infections
Recurrent erysipelas

55
Q

What is tinea manum?

A

Refers to involvement of the hands in general

56
Q

What is tinea manum secondary to?

A

Tinea pedis

57
Q

How may primary tinea manum appear?

A

With occupational exposure to dermatophytes

58
Q

What are the clinical features of tinea manum?

A

A large range from dyshydrotic to macerated to dry and scaly

59
Q

What is the most common form of tinea manum and what is it characterised by?

A

Hyperkeratotic form
Characterised by erythematous background, often with painful fissures

60
Q

Which parts of the hands are mostly involved?

A

Fingertips
Metacarpals
Thenar
Hyppothenar eminences
Often nail involvement

61
Q

Where must you always check for fungal involvement for tinea manum?

A

Feet and groin

62
Q

which other infections should be considered for tinea manum?

A

Psoriasis
Dyshydrotic dermatitis
Other forms of hand dermatitis
And fungal reactions

63
Q

When is psoriasis or dermatitis more likely than tinea manum?

A

When the changes are symmetrical, involving both hands

64
Q

When is candidiasis strongly indicated?

A

When the interdigital spaces or nail folds are involved

65
Q

What is tinea unguium?

A

Fungal infection of the nail

66
Q

How does tinea unguium originate?

A

As tinea pedis then spreads to the nails

67
Q

What are the clinical findings for tinea unguium?

A

Toenails are far more likely to be involved than finger nails
When hands are involved, check feet too
Initially, solitary nails are involved, later on multiple nails may be infected, but often 1 or more stay disease free

68
Q

What is the most common form of tine unguium?

A

Distal subungual onychomicosis

69
Q

What colours is the nail in distal subungual onchymicosis?

A

Dirty yellow, when bacterial superinfection occurs, the nail goes dirty brown to green colour

70
Q

What is tinea incognita?

A

A dermatophytes infection without obvious signs of inflammation

71
Q

What is the definition of a fungal id reaction?

A

Distant skin manifestation of an established fungal infection in which the lesions are allergic not infectious

72
Q

What is rthe most typical setting associated with fungal id reaction?

A

Tinea pedis

73
Q

When may an id reaction develop?

A

When systemic anti fungal therapy is limited

74
Q

Which class of drug is used for dermatophytes infection?

A

Benzofurane

75
Q

Which class of drug is used for candidiasis, and deep fungal infections?

A

Benzimidazole

76
Q

Which class of drug is used for onychomycosis, dermatophytes infection, dandidiasis?

A

Triazole

77
Q

Which class of drug is used for dermatophyte infection and onychomycosis?

A

Pyridine

78
Q

Which class of drug is used for onychomycosis?

A

Morpholine

79
Q

What is pityriasis versicolour? (tinea versicolour)

A

Common fungal skin infection

80
Q

Which age group is pityriasis versicolour more common in?

A

Young adults and blacks

81
Q

Which climates is pityriasis versicolour more common in?

A

Tropical and humid climates and thus occurs more in the summer months

82
Q

What are the risk factors for pityriasis versicolour

A

Obesity
Hyperhydrosis
Occlusive clothing
Inadequate hygiene

83
Q

What is the most common. Cause of pityriasis versicolour?

A

Malassezia furfur - a lipophilic yeast with -varying phenotypes

84
Q

What happens to the skin witch Malassezia furfur infection?

A

Changes in skin s=colour due to blockage of melanin production

85
Q

What is the positive test for Malassezia furfur?

A

Potassium hydroxide test

86
Q

what are the typical sites of predilection of pityriasis versicolour?

A

Nape
Back
Chest

87
Q

Where are the lesions spread for pityriasis versicolour?

A

Lateral aspects of trunk, occasionally reaching the umbilicus, thighs and upper inner aspects of the arms

88
Q

What is first seen in pityriasis versicolour?

A

Sharply bordered, dirty yellow, red brown coloured macules are first seen, usually only a few cm in diameter. Later, larger irregular patches may evolve

89
Q

which pattern of macules and patches is more common in the summer for pityriasis versicolour?

A

Sharply defined, hypopigmented macules and patches

90
Q

What does versicolour mean?

A

Presence of both hyper and hypopigmented lesions

91
Q

How do you assess the extent of the disease for pityriasis versicolour?

A

Using wood light examination

92
Q

What is another clinical feature of pityriasis versicolour?

A

Presence of fine bran line scale that can be scraped with a blade depressor to produce the scales (other hypopigmented diseases such as vitiligo do not scale)

93
Q

What are the characteristics of the lesions in pityriasis versicolour?

A

Almost never pruritis and are merely a cosmetic problem

94
Q

What is the treatment for pityriasis versicolour?

A

Topical - shampoo with - imidazoles, selenium sulfide, zinc pyritone

Systemic - itraconazole - 200mg daily for a week, 100mg daily for 2 weeks
Ketoconazole 400mg weekly for 2 doses

95
Q

What is candidiasis?

A

A fungal infection caused by a yeast called candida

96
Q

Where is candies albicans naturally found in the body?

A

Oral cavity
GI tract
External genitalia

97
Q

When is Candida albicans in its pathogenic form?

A

When it is converted into a pseudomycelial cell

98
Q

What clinical features suggest the Candida albicans is in its pathogenic form?

A

Erythema and other signs of infection eg fever

99
Q

How do you identify if the Candida albicans is in its pathogenic form?

A

Culture based identification obtained from sites away from the mucosa and orifices suggest an abnormal situation

100
Q

When does Candida albicans cause sepsis?

A

When it is in the blood

101
Q

What are the risk factors for Candida albicans?

A

• Newborn/elderly
• Local factors -obesity, diapers, incontinence, etc
• Pregnancy
• Oral contraceptives/ hormons
• Systemic antibiotics
• Oral corticoids/ citostatics
• Diabetes mellitus
• HIV/AIDS
• Atopic dermatitis

102
Q

What is the common name for acute pseudomembranbous candidiasis?

A

Thrush

103
Q

Where is the involvement of acute pseudomembranous candidiasis?

A

mouth,
throat
skin
scalp
vagina
fingers
nails
bronchi,
lungs
gastrointestinal tract
or become systemic as in septicemia, endocarditis and meningitis.

104
Q

What is acute oral candidiasis clinically?

A

Clinically, white plaques that resemble milk curd form on the buccal mucosa and less commonly on the tongue, gums, palate and pharynx

105
Q

When is more at risk of developing angular cheilitis?

A

Children
Those who drool
Streptococcal infections may also cause angular cheilitis

106
Q

Which disease is complicated by secondary infection with c. Albicans?

A

Diaper candidiasis

107
Q

How do children get diaper candidiasis?

A

Transfer from stool, coupled with irritation and maceration. Same for elderly patients

108
Q

How does Candidal intertrigo get coupled with C. Albicans?

A

Eroded, macerated intertriginous areas are often secondarily infected by C. Albicans

109
Q

What are the typical sites for candidal intertrigo?

A

Groin
Axillae
Areas underneath the breasts

110
Q

What is a clinical clue for candidal intertrigo?

A

Presence of satellite pustules at periphery of the lesion, just beyond the typical erythema and light collaraette scales

111
Q

What is the d/d for candidal intertrigo?

A

Intertrigo
Contact dermatitis
Inverse psoriasis

112
Q

What is the clinical diagnosis of candidal balanitis?

A

White-yellowish pustules or erythematous macules with collarete scale and central white plaques are present

Sometimes, larger white masses of hyphae, similar to oral thrush may be seen
In other instances, erythema with superficial erosions is present with oedema in diabetes

113
Q

Which disease does almost every woman have in her lifetime?

A

Candidal vaginitis

114
Q

What plays a role in the recurrence of candidal vaginitis?

A

Transfer from perianal region

115
Q

What is the clinical manifestation of candidal vaginitis?

A

A diffuse scaling erythema may involve the external genitalia, spreading to inner aspects of the thighs
Pruritis or burning as well as vaginal discharge

116
Q

What can C. Albicans cause on the nail fold and nail bed?

A

Candidal paronychia - painful pus laden infections

117
Q

Describe candidal paronychia

A

Chronic damage to the cuticle, either through manipulation or persistent exposure to moisture

118
Q

What happens to the periungual (fingernail) region when you have candidal paronychia?

A

Scaly, red, swollen and tender to pressure. Pus may ooze from the proximal or lateral nail fold.

119
Q

What causes onychomycosis usually?

A

A secondary infection from C. Albicans to a chronic paronychia