2: Skin Infections Flashcards
What is erysipelas
Superficial form of cellulitis that affects upper dermis and subcutaneous tissue
What causes erysipelas
Group A streptococcus
How will erysipelas present
Well demarcated erythematous patch
What causes cellulitis
- Staphylococcus aureus
2. Group A streptococcus
What is cellulitis
Infection of lower dermis and SC tissue
How will cellulitis present
Erythematous patch with indistinct margins
What may cause necrotising fasciitis
Group A streptococcus and anaerobes
What is necrotising fasciitis an infection of
Fascia and underlying muscle
How will necroitising fasciitis present
Rapidly spreading and worsening infection. May cause necrosis - which can present as crepitus, bulla
What infection may cause folliculitis
S. aureus
P. aeruginosa
What is folliculitis
Infection of hair follicles
What infection causes impetigo
- Staphylococcus aurea
- Group A streptococcus
What is impetigo
Infection of superficial epidermis
How will impetigo present
Erythematous lesions with yellow crusting
What may cause staphylococcal scaled skin syndrome
Exotoxin released by staphylococcus aureus
What are the two types of HSV
HSVI = herpes labialis (Oral)
HSV2 = herpes genitalis
What is HSV I
Oral Infection
What is HSV 2
Genital Infection
What causes shingles
Herpes Zoster Virus
What causes herpes zoster opthalmicus
VZV
How will herpes zoster opthalmicus present
- Fever, Headache
- Maculo-papular rash over distribution of ophthalmic. N
- Reduced corneal sensitivity
What are low risk HPV virus serotypes
6 and 11
What do low risk HPV serotypes cause
Anogenital warts
How will warts present
Skin coloured, white scaly patches that present with cauliflower type appearance
What are the high risk hPV serotypes
16 and 18
What do high-risk serotypes cause
Cervical cancer
What are superficial fungal infections
Fungal infections that affect superifical layers of skin, hair or nails
What are the three types of superficial fungal infections
- Dermatophytes
- Yeasts
- Moulds
What is the main dermatophyte skin infection
Tinea (Ring-Worm)
What are two types of yeast superficial skin infections
Candidiasis
Malassezia
What is tinea corpis
Tinea infection of glaborous skin
How will tinea corpis lesions present
Clearly defined circular lesions - normally of the trunk and limbs. That have raised and scaly edges. Often itchy
What is tinea pedis
Athletes foot
: Scaling of skin between toes
What is tinea capitis
Tinea infection of the scalp
How will tinea capitis present
Loss of sections of hair with scaling and flaking in those regions
What is tinea unguium
Tinea infection of the nail
How will tinea unguium present
Yellow, thickening and crumbling of the nail
What is tinea incognito
Incorrect treatment of tinea infection with corticosteroids
How will tinea incognito present
Less-demarcated erythematous lesions
How will oral candidiasis present
White plaques on mucosa
How will candiasis present
Erythema with adjacent satellite lesions in flexures
What is pityriasis also known as
Tinea versicolour
What causes tinea versicolour
Infection with malassezia furfur
How will pityriasis present clinically
Scaly brown patches on trunk that fail to tan
How are fungal infections often diagnosed
- Skin scrapings
- Hair or nail clippings
- Skin swabs
What cream can be used to treat fungal infections
Terbinafine
If a severe fungal infection, what may be used
Oral Itraconazole
Why should corticosteroids not be used to manage fungal infections
Leads to tinea incognito
What are two examples of skin infestations
- Scabies
2. Cutaneous leishmaniasis
How will scabies infections present
- Intense pruritus at night
- Burning sensation
- Elongated erythematous papules (2-10m m)
- Scattered vesicles filled with clear or cloudy fluid
How will cutaneous leishmaniasis present
Multiple red macules-papules that occur around sand-fly bite that quickly increase in size and develop central ulceration
Define cellulitus
Infection of dermis and underlying upper subcutaneous tissue
What are the three bacteria to cause cellulitis
- Staphylococcus aureus
- Streptococcus progenies
- Pasterulla mulocida
What is a risk factor for pasterurella mulocida
Secondary to bites from cats/dogs
How will cellulitis present clinically
- Poorly- demarcted erythematous lesion
- Commonly over the shins
- May have systemic upset
If caused by which bacteria will cellulitis have purulent exudate
S.aureus
What is the difference between erysipelas and cellulitis
Erysipelas - Infection of superficial dermis and epidermis
How is the diagnosis of cellulitis usually made
Clinically.
What is used to classify cellulitis
Eron Classification
What is Eron Class I cellulitis
- No Systemic Upset
2. No uncontrolled co-morbidities
What is Eron Class 2 cellulitis
- Systemic upset
2. Person is well, but with uncontrolled co-morbidities
What is Eron Class 3 Cellulitis
- Significant systemic upset
2. Limb threatening infection secondary to vascular compromise
What is Eron Class 4 Cellulitis
Necrotising fasciitis or sepsis
What are the 6 criteria for admitting someone to hospital with cellulitis for IV Abx
- Immunocompromised
- Less than 1y/o or Frail
- Eron class III or IV
- Significant lymphedema
- Deteriorating condition
- Peri-orbital or facial
What is first-line antibiotic for cellulitis
Flucloxacillin
If individuals are allergic to penicillin, what should be given instead of flucloxacillin
Clarithromycin or Clindamycin
What are three possible ccomplications of cellulitis
- Necroitisng fasciitis
- Septicaemia
- Abscess
What is erysipleas
Superficial infection of superficial dermis and SC tissue
What causes Erysipelas
Group A streptococcus
Give an example of a Group A streptococcus
Streptococcus Pyogenes
How can erysipelas be distinguished from cellulitus
Well-demarcated, raised borders
Where will 80% of erysipelas present
Lower limbs
How will erysipelas present clinically
Erythematous, Oedematous, Warm lesions of lower limb with lymphagitis
What is lymphaginitis
Red streaks will project form the lesion representing inflammation of lymphatic vessels
What is the difference between cellulitis and erysipelas in causative agents
Most commonly:
Cellulitis = Staph.A
Erysipelas = Group A Strep.
What causes staphylococcal scalded skin syndrome
Epidermolytic toxin released by staphylococcus
What typically precede staphylococcal scalded skin syndrome
A mucocutaenous staphylococcal infection such as impetigo
In which population does staphylococcal scalded skin syndrome occur
Children
What time period does SSS present
Hours-Days
How will SSS present clinically
Starts with fever, malaise and erythematous skin - that gives a scalded appearance. Then followed by flaccid bullae. Leisons are extremely common
Over which regions is SSS lesions more common
Face
Neck
Axilla
Groin
What other symptom is present in SSS
Peril-Oral scaling
What sign is positive in SSS
Nikolosky’s sign positive
How can SSS be distinguished from SJS and TEN
No mucosal involvement
Explain pathophysiology of SSS
Staphylococcus releases exotoxin A and B. Which then cleave desmoglein-3 of the epidermis.
What is first-line management for SSS
Antibiotics: penicillinase-resistant antibiotics (nafcillin, oxacillin)
How long does recovery usually take for SSS
15-19d