6- Dermatology (Skin infections: bacterial and fungal) Flashcards

1
Q

folliculitis background

A
  • Folliculitis means an inflammation or infection of the hair follicles of the skin.
  • Due to obstruction in pilosebaceous glands +- infection
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2
Q

causes of folliculitis

A
  • Infection e.g. S.aureus, fungal e.g. Candida spp, herpetic folliculitis (HSV)
  • Immune system e.g. eosinophilic folliculitis
  • Physical irritation
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3
Q

risk factors folliculitis

A

 Uncut beard
 Shaving ‘against the grain’
 Thick hair
 Excessive sweating
 Skin abrasion

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4
Q

presentation of folliculitis

A

It may occur as a relatively trivial irritation - superficial folliculitis, or as a more deep-seated process involving the lower hair follicle

Symptoms
- Rash
- Scratch
- Pustule
- Erythema if deep folliculitis
- Regional draining of lymph nodes should be checked for adenitis ->mild folliculitis
- Folliculitis of eyelast- stye

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5
Q

management of folliculitis

A
  • Avoid precipitating factors
  • Use moisturizing shaving products
  • Shave with the grain
  • Good skin hygiene
  • Superficial – antiseptics
  • Deeper- oral antibiotics e.g. flucloxacillin, erythromycin
  • May need surgery
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6
Q

cellulitis vs erysipelas

A

Cellulitis
- Acute, painful and potentially serious infection of the skin and subcutaneous tissues.
- Infection of the dermis and subcut tissue

Erysipelas
- Acute superficial from of cellulitis and involves the dermis and upper subcut tissue

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7
Q

which pathogens cause cellulitis and erysipelas

A

Streptococcous pyogens (group A Beta haemolytic) and staphylococcus aureus

rarely fungal

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8
Q

risk factors for cellulitis

A
  • Previous cellulitis
  • Immunosuppression
  • Venous insuff
  • Elder
  • Alcohol dependency
  • IV drug use
  • Insect bites
  • Obesity
  • Athletes foot
  • Diabetes
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9
Q

presentation of cellulitis

A
  • Poorly demarcated borders
  • Lower limb unilaterally
    o Swelling (tumor)
    o Erythema (rubor)
    o Warmth (calor)
    o Pain (dolor)
  • Sometimes precipitating skin lesion
  • Blisters and bullae
  • Systemic symptoms e.g. fever and malaise
  • Red line streaking represents progression of infection to lymphatic system
  • Crepitus
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10
Q

how can erysipelas be distinguished from cellulitis

A

distinguished from cellulitis by well-defined, red raised border

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11
Q

investigations for cellulitis

A

Bloods
- FBC
- CRP
- UEs
- LFTs
- Blood culture

Swabs
- culture fluids

Imaging
- US may be useful if abscess if suspected

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12
Q

Management of cellulitis

A
  • Antibiotics e.g. Fluclox or benzylpenicillin
  • Rest and elevate
  • NSAIDS
  • Clean wound (debride)
  • Emollient
  • Draw margins
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13
Q

complications of cellulitis

A

abscess and sepsis

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14
Q

impetigo background

A

Superficial bacterial skin infection
- Very contagious
- Classified as
o Non-bullous
o Bullous

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15
Q

bullous impetigo

A
  • Epidermolytic toxins released by S.aureus break down proteins that hold skin cells together
  • This causes fluid filled vesicles
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16
Q

impetigo causative organisms

A
  • Usually Staphylococcus aureus
  • Streptococcus pyogenes
17
Q

pathophysiology of impetigo

A
  • Occurs when bacteria enter via a break in the skin
  • Can be otherwise healthy skin
  • Or related to eczema or dermatitis
18
Q

risk factos for impetigo

A
  • Age. Impetigo occurs most commonly in children ages 2 to 5.
  • Close contact. Impetigo spreads easily within families, in crowded settings, such as schools and child care facilities, and from participating in sports that involve skin-to-skin contact.
  • Warm, humid weather. Impetigo infections are more common in warm, humid weather.
  • Broken skin The bacteria that cause impetigo often enter the skin through a small cut, insect bite or rash.
  • Other health conditions. Children with other skin conditions, such as atopic dermatitis (eczema), are more likely to develop impetigo. Older adults, people with diabetes or people with a weakened immune system are also more likely to get it.
19
Q

presentation of nonbullous impetigo

A
  • Around nose or mouth
  • ‘golden crust’
  • Unsightly
  • No systemic symptoms of illness
20
Q

presentation of bullous impetigo

A
  • More common in neonates and children <2
  • Always causes by staphylococcus aureus
  • Fluid filled vesicles which grow in size and burst, forming a “golden crust:
  • Heal without scaring
  • Can be painful and itchy
  • Systemic symptoms
  • I severe infection called : staphylococcus scalded skin syndrome
21
Q

Investigations for impetigo

A
  • Swabs of vesicles can confirm diagnosis, bacteria and antibiotic sensitivities
22
Q

management of nonbullous impetigo

A

First line:
- Topical fusidic acid
- Hydrogen peroxide 1% cream

Second line (i.e. severe): Flucloxacillin

23
Q

Stopping the spread of impetigo

A
  • Impetigo is very contagious so children should be kept off school during infection until lesions have healed or had antibiotics for >48 hours

Advice for patient
- to not scratch or touch lesions
- hand hygiene
- avoid sharing face towels and cutlery

24
Q

Complications of impetigo

A

Impetigo usually responds well to treatment without any long term adverse effects. Rarely there can be complications:
* Cellulitis if the infection gets deeper in the skin
* Sepsis
* Scarring
* Post streptococcal glomerulonephritis
* Staphylococcus scalded skin syndrome
* Scarlet fever

25
Q

superficial fungal infections background

A
  • Common and usually mild infections of superficial layers of the:
    o Skin
    o Nails
    o Hair
  • Can be serious in immunosuppressed
26
Q

3 main groups of fungal infections

A
  • Dermatophytes (tinea/ringworm)
  • Yeasts e.g. candidiasis, Malassezia furfur
  • Moulds e.g. aspergillus
27
Q

tinea corporis

A

tinea infection of the trunk and limbs

Presentation
Itchy, circular or annular lesions with a clearly defined, raised and scaly edge is typical

28
Q

Tinea cruris

A

tinea infection of the groin and natal cleft

Presentation
Very itchy, similar to tinea corporis

29
Q

Tinea pedis

A

Athlete’s foot

Presentation
Moist scaling and fissuring in toewebs, spreading to the sole and dorsal aspect of the foot

30
Q

Tinea manuum (

A

tinea infection of the hand

Presentation
Scaling and dryness in the palmar creases

31
Q

Tinea capitis

A

scalp ringworm

Presentation
- Patches of broken hair, scaling and inflammation
- bald patches

32
Q

Tinea unguium

A

tinea infection of the nail

Presentation
Yellow discolouration, thickened and crumbly nail

33
Q

Tinea incognito

A

inappropriate treatment of tinea infection with topical or systemic corticosteroids

Presentation
Ill-defined and less scaly lesions

34
Q

Candidiasis

A
  • white plaques on mucosal areas
  • erythema with satellite lesions in flexures
35
Q

Pityriasis/Tinea versicolor

A

infection with Malassezia furfur

Presentation
- Scaly pale brown patches on upper trunk that fail to tan on sun exposure, usually asymptomatic

36
Q

investigations for fungal skin infections

A

Investigations
- Skin scraping, hair or nail clippings
- Skin swabs for yeasts

37
Q

Management of fungal skin infections

A
  • Treat precipitating factors
    o e.g. underlying immunosuppressive condition
    o Moist environment
  • Topical antifungal agents e.g. terbinafine cream
  • Oral antifungal e.g. Itraconazole for severe, widespread or nail infection
  • Avoid use of topical steroids -> can lead to tinea incognito