Skin Infections

Skin Infections Type Description Inflammatory reaction of hair follicle Presents pustules or papules Most common in hot weather Not always caused by infection Non-infective: Causes: maceration, obesity, heavy sweating, contact with occlusive substance e.g. oil, shaving and waxing Drugs: corticosteroids, epidermal growth and EFGR inhibitors, immune checkpoint inhibitor’s, Folliculitis some antibiotics and antiepileptics Management: warm compressors, antiseptic washes, clean sharp razors when shaving Infective: S. aureus -> most common Pseudomonas aeruginosa -> usually acquired from hot tubs and spas If suspected -> bacterial swan for cultures and susceptibility PCR for HSV Management: oral or topical micro therapy -> antibiotics, antivirals or anti-fungal Most often in children Contagious Spread: Limited: up to 2 sores Extensive: more than 2 sores Classification: Nonbullous Round, puss filled or gold blisters papules -> rupture -> yellow to thick crusts May be itchy or irritating Not painful May be cause by S. pyrogens (GAS) or S. Aurus Most commonly at the face Esp around nose and mouth Lower extremities Regional lymphadenopathy Bullous Large and floppy blisters -> may rupture -> thin brown crusts Rapidly develop within erythema’s, shallow erosions Systemic features e.g. fever and malaise More common in this type Impetigo Locations: Trunk and upper extremities Negative Nikolsky sign Rare manifestation: Ulcerative impetigo -> extends into the dermis Coin sized superficial ulcer with punched out appearance Do not require initial skin swab before staring empiric antibiotic therapy Unless diagnosis is unclear or it is recurrent Investigations Swab for culture and sensitivity Superficial infection of the upper dermis The affected area is raised Has a clear line of demarcation between infected and non-infected tissue Most common location is the lower limp Classical involves the facial skin in a butterfly pattern Second most common Common causes: Group A beta haemolytic Step Esp. S pyogenes Investigations Not routinely needed if mild and clinically clear Blood cultures Indications: systemic features, immunocompromised or severe infections Inflammatory markers Systemic illness features Skin swabs Only do if there are blisters and open wound Limb ultrasound If diagnostic uncertainty Management: Rest and elevation of the affected area -> improves symptoms Erysipelas Addressing contributing factors E.g. lymphedema or cardiac failure or venous insufficiency Oral antibiotics Adequate for most patients without systemic features IV antibiotics Indications: Unable to tolerate and absorb oral therapy Extensive erythema Systemic features of infection Infection that extends deeper into the dermis than erysipelas and involves the subcutaneous tissue Can complicate: Wounds: cuts and abrasions Insect bites Varicella Shingles Sabies In children most often periorbital/preseptal Most common cause GAS Investigations Inflammatory markers Indicated when have systemic symptoms, admission required Blood cultures Cellulitis Indicated when there is sepsis, immunocompromise or severe or rapid progressive infection Wound/pus wound Open wound, ulcer or abscess Guides antibiotic choice Ultrasounds Failure to improve Suspected abscess Can detect drainable collection CR or MRI Indicated when there is a deep infection or disproportions pain Allows to assess disease extent and complications Diffusely spread Cellulitis caused by S. aureus including MRSA is less frequent and is often associated with penetrating trauma or ulcerations Management Same as above Key Info Bilateral LL erysipelas and cellulitis are rare Always consider DDx Management of cellulitis or DDx for cellulitis DVT Venous insufficiency Inflammatory skin conditions E.g. eczema, dermatitis, vasculitis and gout Infections Trauma