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IMED2001 UWA > Fungi - Clinical Case studies: Skin and soft tissue infections > Flashcards

Fungi - Clinical Case studies: Skin and soft tissue infections Flashcards

1
Q

What we should understand:

A

Focus on common presentations in clinical settings:

Is it fungal?

Pitfalls

Commonly encountered fungal infections in clinical settings:

Identification

Diagnosis (clinical, microbiological)

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2
Q

How does fungal infections most commonly present?

A

As opportunistic infections (Cutaneous infections, abdominal infection, lung infection, systemic infection)

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3
Q

How are fungal infections acquired?

A

From soil, tap water, mouldy kitchen/bathroom

Human-to-human transmission is rare with the exception of tinea (ringworm)

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4
Q

How are clinical presentations of fungal infections classified?

A

Superficial and cutaneous mycoses

Subcutaneous mycoses

Opportunistic mycoses

Deep seated mycoses

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5
Q

What are superficial mycoses? What are cutaneous mycoses?

A

Limited to outer layer of skin and hairshaft. The cutaneous mycoses also include deeper layers such as the epidermis. Thus they include invasive hair and nail infections.

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6
Q

What are subcutaneous mycoses?

A

Involve the dermis, subcutaneous tissues, muscles and fascia

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7
Q

What fungi are commonly involved in subcutaneous mycoses?

A

Dematiaceous hyphomycoses

Some diamorphic fungi (sporothrix and candida)

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8
Q

What are deep seated mycoses?

A

Systemic infections in hosts who are not necessarily immunosuppressed.

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9
Q

What fungi cause deep seated mycoses?

A

Mostly caused by dimorphic fungi with the exception of cryptococcus neoformans. (most commonly coccidioides immitis and paracoccidioides brasiliensis)

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10
Q

Which fungi are capable of causing opportunistic infections?

A

Most fungi can but the most common causes are:

Mucormycosis

Hyalohyphomycosis

Phaeohyphomycosis

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11
Q

How can a rash be differentiated?

A

Onset (abrupt, gradual spreading, recurrent)

Character (macular, papular, vesicular)

Site and Distribution (Localised, patchy, generalised, mucosal involvement, photosensitive or dermatomal)

Associated symptoms (viral prodromal)

Associated risk factors

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12
Q

What does macular mean?

A

Consisting of a distinct spot or spots.

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13
Q

What does papular mean?

A

Composed of elevated bumps

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14
Q

What does vesicular mean?

A

Blistering rash

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15
Q

What else can a localized rash be? (Differential diagnosis)

A

Contact dermatitis with or without bacterial colonisations

Psoriasis

Radiation dermatitis

Fixed drug reactions

Infective cause

Systemic reaction (Autoimmune)

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16
Q

What rashes are important to recognize because they are life threatening?

A

Steven-Johnson syndrome

Drug Rash with Eosinophilia and Systemic Syndrome (DRESS)

Meningococcal bacteraemia

Pemphigus vulgaris

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17
Q

What is Steven-Johnson syndrome?

A

A severe allergic reaction to medications affecting skin and mucus membrane.

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18
Q

What drugs cause Steven-Johnson syndrome?

A

Sulphonamides

Allopurinol

NSAIDs

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19
Q

What does meningococcal rash look like?

A

Petechiae rash caused by peripheral thrombosis/necrosis of tissues.

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20
Q

What is pemphigus vulgaris?

A

Severe autoimmune disease where blisters develop on skin and mucus membranes

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21
Q

What investigations must be conducted for an undiagnosed rash?

A

Guided by history and clinical examinations.

Blood tests include Full blood picture (WBCs and Eosinophil counts), C-reactive protein, and liver function tests.

Histopathological and microbiological testings (H&E stain, immunofluorescence stain for autoimmune disease. microscopy, culture, molecular tests, and serology)

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22
Q

If histology and culture can give definitive diagnosis why is it important to have an idea of what the diagnosis of a condition might be?

A

In order to allow treatment to be initiated asap.

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23
Q

What is candida?

A

A yeast (unicellular fungi)

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24
Q

How do candida reproduce?

A

Budding

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25
Q

Where is candida commonly found?

A

Animals, soil, hospital

Also normal commensals of humans (found on skin, GI tract, and vagina)

26
Q

Why is species identification important for candida?

A

Different species are treated in different ways

27
Q

How does candida cause disease?

A

Coloniser of gut under normal circumstances (pathogenic in immunocompromised)

28
Q

What could cause candida albicans infection in someone who isn’t immunocompromised?

A

It can be caused by Iatrogenic factors such as antibiotic use, indwelling catheters and prosthesis.

29
Q

What kind of disease is most commonly produced by candida?

A

Skin and mucous membrane infections. invasive disease is possible but uncommon.

30
Q

What is intertrigo?

A

An inflammatory condition of skin folds, induced or aggravated by heat, moisture, maceration, friction, and lack of air circulation

31
Q

What are the types of candidiasis?

A

Intertrigo

Localised folliculitis, balanitis

Candida diaper rash

Paronychia (nail infection)

32
Q

What are the types of mucous membrane infections caused by candida?

A

Thrush

Candida esophagitis

Vulvovaginitis

33
Q

What invasive diseases can be caused by candida?

A

Bacteraemia

Endocarditis

Enophthalmitis

Urinary tract candidiasis

34
Q

What does thrush look like?

A

Whitish yellow center surrounded by reddening of the mucous membrane

35
Q

Diagnosis of candida infections:

A

Mostly made from clinical exam

Lab testings (samples from intact pustules, skin biopsy tissue or desquamated skin can help support diagnosis)

Swab is inaccurate

Microscopy and culture as well as histopathology

36
Q

How is candidiasis managed?

A

For most cutaneous disease investigations for underlying predisposing factors are conducted (diabetes, oral antibiotics, treat dermatoses, clean and dry skins appropriately)

Medication (includes topical antifungal which is usually sufficient, oral is used if it isn’t)

37
Q

What medication is used for treatment of candidiasis?

A

Cotrimazole 1% cream B.D for 2 weeks, nystatin 100000 u/g cream BD for 2 weeks

38
Q

How does dermatophyte infection present?

A

Annular lesion (ring-like) with dry scaly skin in the center and slightly raised with inflamed spreading margin.

It can also present as an erythematous rash or plague like.

Hyperkeratotic eruption can also be seen.

Commonly associated with pruritis.

39
Q

What are the 3 important genera of dermatophytes?

A

Trichophytan

Microsporum

Epidermophyton

40
Q

What are the modes of transmission of dermatophyte infections?

A

Anthopophiliac (human to human)

Zoophilic (animal to human)

Geophilic (environment to human)

41
Q

What do dermatophytes require for growth?

A

Keratin

42
Q

What is the infection by dermatophytes called?

A

Tinea

43
Q

What are the types of tinea?

A

Tinea capitis (scalp)

Tinea corporis (body)

Tinea unguium (nails) [oncychomycosis]

Tinea cruris, barabe, pedis, etc

44
Q

What is onychomycosis?

A

Dystrophic nail (only 50% have a fungal aetiology)

45
Q

What is pruritis?

A

severe itching of the skin, as a symptom of various ailments

46
Q

What is hyperkeratosis?

A

Abnormal thickening of the outer layer of the skin

47
Q

How is tinea diagnosed?

A

Skin+nail scrapings and epilated hairs (nail scrapings can be falsely negative in 30% of cases)

Microscopy (fungal hyphae and/or arthroconidia

Culture (more reliable and permits species of fungus involved to be accurately identified.

48
Q

How is tinea treated?

A

Depends on location and organism involved. Topical therapy is only used in tinea corporis, pedis, and cruris.

Tinea capitis and onychomycosis require systemic therapy.

[topical treatment less effective than systemic therapy]

49
Q

What drugs are used to treat tinea?

A

terbinafine (first line since its more effective)

griseofulvin (microsporum canis is less susceptible to terbinafine so griseofulvin is used instead)

50
Q

What is another name for sporotrichosis? Why?

A

Rose handler disease. It is caused by inoculation injury from soil.

51
Q

Where is sporotrichosis commonly seen?

A

Certain parts of Australia (Margaret River regions)

52
Q

How does infection take place in sprotrichosis?

A

Mainly a localising disease which may or may not spread to lymph nodes.

53
Q

How is sporotrichosis diagnosed?

A

Microscopy and culture of skin lesion

54
Q

How is sporotrichosis treated?

A

Itraconazole

55
Q

How does spirotrichosis appear?

A

Initially a primary lesion is developed distally and secondary lesions develop along lymphatic drainage.

56
Q

What other infections have a similar appearance to sporotrichosis?

A

Mycobacterium marinum

Nocardia species

57
Q

What causes chromoblastomycosis?

A

Few different fungi (Cladophilophora carrionii, Fonsecaea pedrosi, Phialophora verrucosa and more)

These fungi get into the skin via inoculation injury and develop over a number of years.

58
Q

Where is chromoblastomycosis mainly found?

A

Tropical and subtropical areas

59
Q

What is the outside appearance of skin that is infected with chromoblastomycosis?

A

Huge cauliflower-like masses appear that present over long periods of time

60
Q

How is chromoblastomycosis diagnosed?

A

Microscopy and culture

61
Q

What other fungi can cause cutaneous mycosis?

A

Hyalohyphomycosis (group of opportunistic mycotic infections caused by non-dematiaceous moulds)

Phaeohyphomycosis (caused by deatiaceous (black) moulds

62
Q

Summary:

A

Many causes of rash:

History is important (exposure, travel, PMH)

Imporant to be able to describe a rash properly

Cutaneous fungal infections:

Generally localized and self-limiting

Disseminated disease can occur in immunosuppressed patients

Caused by a diverse range of fungi with widely different presentations.

Tissue diagnosis for both histopathology and microscopy are important for confirming a diagnosis and treatment.

IMED2001 UWA (44 decks)

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