DERM: Bacterial Infections Flashcards
a “golden honey-coloured” crusted erosion is a characteristic of which skin infection?
impetigo
impetigo is commonly caused by which bacteria?
staphylococcus aureus bacteria
which type of people are. commonly affected by impetigo?
children (especially boys)
when is the peak onset of impetigo?
summer
what can impetigo be classified into?
- non-bullous
- bullous
- ecthyma
what is non-bullous impetigo?
- around the nose or mouth
- do not usually cause systemic symptoms
- Staph/strep invade a minor trauma site
- Pink macule»_space; vesicle/pustule»_space; crusted erosions
- Usually resolves in 2-4 weeks without treatment
what is bullous impetigo?
- always caused by the staphylococcus aureus bacteria
- more common in neonates and children under 2 years
- may be feverish and generally unwell
- heals without scarring
which bacteria causes impetigo?
Most commonly Staphylococcus aureus
or Streptococcus Pyogenes
what are the risk factors for impetigo?
- Atopic Eczema
- Scabies
- Skin Trauma (Chickenpox, Insect bite, Wound, Burn, dermatitis)
what is ecthyma impetigo?
- Strep. pyogenes main cause
- Starts as non-bullous»_space; punched-out necrotic ulcer
- Slow healing, leaves scar
which type of impetigo causes a scar?
ecthyma impetigo
what are some complications of impetigo?
- Cellulitis if the infection gets deeper in the skin
- Sepsis
- Scarring
- Post streptococcal glomerulonephritis
- Staphylococcus scalded skin syndrome
- Scarlet fever
how do you diagnose impetigo?
Diagnosed clinically
Bacterial swabs for confirmation
how do you treat impetigo?
- Clean wound with antiseptic
- Cover affected areas
- If extensive, oral abx recommended (e.g. flucloxacillin)
- Avoid contact with others (physical, towels/flannels etc)
- Children must avoid school until crust dries
- Wash daily with antibacterial soap and identify the source of infection to avoid re-infection
what is cellulitis?
Cellulitis is an infection of the skin and the soft tissues underneath.
- Involves deep subcutaneous tissue
what is Erysipelas?
an acute, superficial form of cellulitis
- Only involves dermis and upper subcutaneous tissue
how does cellulitis present?
- Erythema (red discolouration)
- Warm or hot to touch
- Tense
- Thickened
- Oedematous
- Bullae (fluid filled blisters)
- A golden-yellow crust can be present and indicate a staphylococcus aureus infection
- mostly lower limbs
- mostly unilateral
- systemically unwell
what are the most common causes of cellulitis?
The most common causes are:
Staphylococcus aureus
- Group A Streptococcus (mainly streptococcus pyogenes)
- Group C Streptococcus (mainly Streptococcus dysgalactiae)
Other causes: MRSA
necrotising fasciitis can often appear similar to cellulitis, what are the differences?
- Pain is often far more extreme than cellulitis
- Crepitus on palpation (soft tissue gas)
- More rapid progression
- Patient more systemically unwell
what are the risk factors for cellulitis/Erysipelas?
- Previous episodes
- Fissures in toes/heels
E.g. athletes foot - Venous disease
- Current or prior injury
Trauma, surgery - Immunodeficiency
- Obesity and diabetes
- Pregnancy
how is Erysipelas distinguished from cellulitis?
Erysipelas is distinguished from cellulitis by a well-defined, red, raised border
what are some complications of cellulitis?
LOCAL NECROSIS
ABSCESS
SEPTICAEMIA
how do you diagnose cellulitis?
Diagnosed largely clinically
Blood culture or wound swabs for causative organism
how do you treat cellulitis?
Antibiotics: Flucloxacillin
Supportive care:
- Rest
- Elevation
- Sterile dressings
- analgesia
what is folliculitis?
Group of skin conditions where hair follicles are inflamed
Acne and rosacea is a type of folliculitis
what are some causes of folliculitis?
- infection.
- occlusion (blockage).
- irritation (regrowth from shaving, waxing etc).
what are the general clinical features of folliculitis?
- Tender red spot, often with surface pustule
- Can be superficial or deep
- Affects anywhere with hair (Chest, Back, Buttocks, Arms and leg)
how do you diagnose folliculitis?
Diagnosed clinically
Bacterial swabs for confirmation
how do you treat folliculitis?
- Careful hygiene
- Antiseptic cleanser
- BACTERIAL: Topical/oral antibiotics e.g. tetracycline
- VIRAL: Aciclovir
- YEAST/FUNGI: Topical/oral antifungal
what is intertrigo?
- Rash in flexures/body folds
- May affect one or multiple sites
- Affects males and females of any age
what are the risk factors for intertrigo?
- Obesity
- Genetic tendency
- Hyperhidrosis (excess sweating)
what causes intertrigo?
- Flexural skin has a high surface temp
- Moisture is stopped from evaporating due to folds
- Friction from movement of fold skin can cause chafing
- Bacteria and/or yeast multiply in warm, moist settings
- Other skin infections (e.g. thrush, tinea) can cause intertrigo
- Other skin conditions (flexural psoriasis, various dermatitises)
what are some general clinical features of intertrigo?
- Rash in flexures/body folds e.g. behind ears, axillae, groin, buttocks, finger/toe webs.
- Skin is inflamed and uncomfortable
- Skin may become moist, leading to fissures and peeling
what are some complications of intertrigo?
- tissue infection e.g. cellulitis
- staph. scalded skin syndrome.
- glomerulonephritis
how do you diagnose intertrigo?
Bacterial swabs for confirmation
Skin biopsy if unusual or not responding to treatment
how do you treat intertrigo?
- Antiperspirant
- BACTERIA: Topical/oral abx
- YEAST/FUNGI: Topical/oral antifungals
- INFLAMMATION: Low potency topical steroids
E.g. hydrocortisone
Calcineurin inhibitors
E.g. tacrolimus
