Bacterial Diseases of the Skin

Bacterial Diseases of the Skin Bacterial infection of the skin:  The surface of the skin has microorganisms, which are most numerous in moist hairy areas rich in sebaceous glands.  Staphylococcus aureus and group A beta-hemolytic streptococci account for the majority of skin and soft tissue infections.

 S. aureus invades skin and causes:  Impetigo, folliculitis, cellulitis, and furuncles.  Elaboration of toxins by S. aureus causes the lesions of bullous impetigo and staphylococcal scalded skin syndrome.  Streptococci invade traumatic skin lesions and cause impetigo, erysipelas, cellulitis, and lymphangitis. Lesion Etiology/Microorganism Presentation Investigations/Treatment

Caused by staphylococci, streptococci or by both together. A thin-walled clear blister forms The diagnosis is usually made • before rupturing to leave area of on clinical grounds  Gram The bullous type is usually exudation and yellowish stains or swabs taken for culture caused by crusting  Staphylococcus aureus • Mild infection and localised Impetigo exfoliative toxins  cleave the Lesions enlarge and become lesions  Topical antibiotics cell adhesion molecule contiguous with the others • • Widespread lesions or more The crusted ulcerated type is Often multiple particularly severe infection  Oral caused by around the face. Flucloxacillin Streptococci.

Ecthyma This term describes ulcers forming under a crusted surface infection.

Usually on the lower extremities of children Buttocks, thighs and May be due to insect bite or of legs neglected minor trauma.  Due to Staph aureus or Strep The ulcer is full thickness and heals with scarring and pigmentation Superficial folliculitis  Folliculitis Deep folliculitis Furuncle and carbuncle, Sycosis barbae Lesion Etiology/Microorganism Presentation Investigations/Treatment Complications Folliculitis Inflammation of the hair follicle Painless or tender pustule that eventually Superficial lesions  may respond to heals without scarring. local antiseptics or persistent cases  may need topical antibiotics Staph aureus Beard areas, axilla,  buttock Widespread and severe folliculitis  oral flucloxacillin Legs (Chronic) Furuncle Deep inflammatory nodule {Boil} developing from a preceding folliculitis Begins as a firm, tender, erythematous nodule that becomes fluctuant and painful and commonly ruptures spontaneoiusly and Cavernous sinus thrombosis is an later may discharge pus unusual complication of boils on the central face. drainage of pus and Systemic Staph aureus May have Fever treatment with flucloxacillin Septicaemia may occur but is Healing leave a scar rare.

Lesions favor areas prone to friction or minor trauma thighs, buttocks, groin and axillae. Carbuncle A group of adjacent hair follicles becomes deeply infected with Staphylococcus aureus, leading to a swollen painful suppurating area discharging pus from several points. Swollen painful suppurating area discharging pus from several points. Incision and drainage. Larger than a Furuncle Staph aureus (Boil) Needs both topical and systemic The pain and systemic antibiotics. symptoms are greater than those of a boil.

Diabetes should be excluded. Sycosis Localized inflammation is treated Follicular papules or Barbae Staph aureus topically pustules Increases in men with shaving Extensive disease is treated with oral antibiotics Cellulitis Erysipelas is a superficial cellulitis The subcutaneous tissues are involved and Elevation and rest Often follows an injury and favours the area is more raised areas of oedema. and swollen, and the Systemic antibiotics oral or I.V erythema less Group A streptococci marginated. Recurrence after antibiotic treatment occurs in 18% to 30% of cases. Malaise, chills, and fever Paronychia Bright red swelling of the proximal and lateral nailfold Staphyloccocci Bright red swelling of Warm water compresses may be the proximal and lateral effective. nailfold Topical or systemic antistaphylococcal Painful antibiotic Rapid onset Ritter’s STAPHYLOCOCCAL SCALDED Disease SKIN SYNDROME Erythema and tenderness followed by the loosening of large areas of overlying epidermis More In children and infant Tender red skin Heals 7 - 14 day Fluid from bullae is Caused by a toxin produced by sterile but the S. aureus Oral or intravenous flucloxacillin staphylococcal infection elsewhere can be isolated from The patient’s skin lubricated with light (e.g. impetigo or conjunctivitis) distant sites, such as the lotions nose.

Toxins cleave the superficial skin adhesion molecule to disrupt adhesion high in the epidermis causing the stratum corneum to slough off.