14. Skin Infections .pptx

Skin Infections Dr Joseph Thomas Impetigo, Erysipelas, Cellulitis Impetigo • Impetigo is a superficial skin infection • Crusting or bullae • Ecthyma is an ulcerative form of impetigo Features • No predisposing lesion is identified in most patients • Follow any type of break in the skin • Gene...

Skin Infections Dr Joseph Thomas Impetigo, Erysipelas, Cellulitis Impetigo • Impetigo is a superficial skin infection • Crusting or bullae • Ecthyma is an ulcerative form of impetigo Features • No predisposing lesion is identified in most patients • Follow any type of break in the skin • General risk factors – moist environment poor hygiene chronic nasopharyngeal carriage – Staph. or Streptococci. • Staphylococcus aureus is the predominant cause Impetigo - Diagnosis • Impetigo may be bullous or nonbullous • Bullae are caused by exfoliative toxin produced by Staphylococci • Characteristic appearance • Culture from lesion • Nasal culture for MRSA Treatment impetigo • Affected area - washed gently with soap and water several times a day to remove any crusts • Topical agents - Topical mupirocin, fusidic acid Topical antibiotic ointment 3 times a day for 7 days, Fusidic acid 2% cream 3 to 4 times a day until lesions resolve • Oral antibiotics Dicloxacillin or cephalexin 250 to 500 mg 4 times -10 days • Immunocompromised patients - extensive or resistant impetigo lesions Clindamycin 300 mg every 6 hours Erythromycin 250 mg every 6 hours Erysipelas Erysipelas • Form of cellulitis characterised by pronounced superficial inflammation • The term erysipelas is commonly used when the face is affected. Causative organism • Adults : Streptococci (particularly Streptococcus pyogenes) Staphylococcus aureus • Children: Haemophilus influenzae Erysipelas • Skin infection involving the dermis , but it may also extend to the superficial cutaneous lymphatics • Characterized - area of erythema that is well demarcated, raised • Lower extremities, face • St Anthony's fire due to the intense rash associated with it Clinical feature Erysipelas • Affects infants and older people but can affect any age group • Risk factors are similar to those for other forms of cellulitis • Previous episode(s) of erysipelas • Breaks in skin barrier – insect bites, eczema • Current or prior injury (eg, trauma, surgical wounds, radiotherapy) • Nasopharyngeal infection • Venous disease • Immune deficiency – Diabetes, alcoholism, HIV • Nephrotic syndrome Causative organism • Unlike cellulitis, almost all erysipelas is caused by Group A beta-haemolytic streptococci - Streptococcus pyogenes • Staphylococcus aureus • Streptococcus pneumoniae • Klebsiella pneumoniae • Haemophilus influenzae also rarely cause erysipelas Clinical features • Symptoms and signs - abrupt in onset, accompanied by fevers, chills and rigor • Affects lower limbs face characteristic butterfly distribution on the cheeks and across the bridge of the nose • Infants - umbilicus or diaper/napkin region • Affected skin - very sharp, raised border • Bright red, firm and swollen. It may be finely dimpled (like an orange skin) • May be blistered - severe cases may become necrotic • Cellulitis does not usually exhibit such marked swelling but shares other features with erysipelas, such as pain and increased warmth of affected skin Complications • Rare • Abscess • Gangrene • Thrombophlebitis • Cavernous sinus thrombosis • Infections distant sites • Infective endocarditis • Septic arthritis • Bursitis • Tendonitis • Post-streptococcal glomerulonephritis Diagnosis • A history of a relevant injury • Tests may reveal: Raised white cell count Raised C-reactive protein Positive blood culture identifying the organism • General Management Cold packs and analgesics to relieve local discomfort Elevation of an infected limb to reduce local swelling Compression stockings Wound care with saline dressings that are frequently changed • Antibiotics Oral or intravenous penicillin is the antibiotic of first choice Erythromycin or roxithromycin - penicillin allergy Vancomycin is used for facial erysipelas caused by MRSA • Treatment is usually for 10–14 days Cellulitis • Acute bacterial infection of the skin and subcutaneous tissue • Pain, warmth, rapidly spreading erythema, and edema • Fever • Regional lymph nodes may enlarge in more serious infections. Clinical features • Fever, chills, tachycardia, headache, hypotension, and delirium may precede cutaneous findings by several hours • Many patients do not appear ill. • Cellulitis with rapid spread of infection, rapidly increasing pain, hypotension, delirium, or skin sloughing, particularly with bullae and fevers, suggests life-threatening infection. Most common causes of cellulitis • Streptococcus pyogenes • Staphylococcus aureus • Cellulitis is most often caused by group A Beta-hemolytic streptococci • Skin barrier is usually compromised • Streptococci cause diffuse, rapidly spreading infection enzymes produced by the organism (streptokinase, DNase, hyaluronidase) break down cellular components that would contain and localize the inflammation Cellulitis • Most cellulitis - nonpurulent • Cellulitis - accompanied by one or more pustules, furuncles or abscesses with or without purulent drainage or exudate • Most common in the lower extremities • Major findings are local erythema and tenderness and, in more severe infections, often lymphangitis and regional lymphadenopathy. Cellulitis Well defined borders vs ill-defined borders Cellulitis Cellulitis following vaccination / insect bite Diagnosis • Examination • Rule out diabetes, renal failure etc • Sometimes blood cultures • Sometime tissue cultures • Rule out local underlying pathologies Complications • Most cellulitis resolves quickly with treatment • Local abscesses - requires incision and drainage • Serious but rare complications – necrotizing fascitis, bacteremia with metastatic foci of infection • Recurrences in the same area are common causing serious damage to the lymphatics chronic lymphatic obstruction lymphedema General management • Immobilization and elevation of the affected area help reduce edema • Cool, wet dressings relieve local discomfort • Analgesics • Antipyretics Nonpurulent, uncomplicated cellulitis • Empiric therapy effective against both group A streptococci and S. aureus • Oral therapy – dicloxacillin 250 mg or cephalexin 500 mg 4 times a day. levofloxacin 500 mg or moxifloxacin 400 mg once a day • allergic to penicillin oral clindamycin 300 to 450 mg 3 times a day oral macrolide (clarithromycin 250 - 500 mg 2 times a day) azithromycin 500 mg on 1st day, then 250 mg once a day) Purulent high risk cellulitis Coverage for MRSA in patients with the following: • Penetrating trauma • Surgical wounds • Recent hospitalization or nursing home exposure • IV drug use • Proximity of infection to an implanted medical device such as a prosthetic joint • Previous MRSA infection • Known nasal colonization with MRSA • High-risk symptoms for serious infection High risk symptoms • High-risk symptoms - deeper, invasive, systemic • Pain disproportionate to physical findings • Cutaneous hemorrhage • Bullae • Skin sloughing • Skin anesthesia • Rapid progression • Tissue gas • Symptoms of systemic toxicity (fever or hypothermia, tachycardia, hypotension, delirium) Severe Cellulitis • High-risk symptoms with suspected or confirmed MRSA, or who have failed oral therapy are hospitalized and given the following: • Vancomycin 15 mg/kg IV every 12 hours is the drug of choice • Linezolid 600 mg IV every 12 hours for 10 to 14 days, usually for highly resistant MRSA • Teicoplanin 6 mg/kg IV every 12 hours for 2 doses, followed by 3 or 6 mg/kg IV or IM once a day Boil / furuncle Furuncle / Carbuncle • Folliculitis / Boil – Hair follicle is inflamed • Furuncle – Around the hair follicle and contains pus • Carbuncle – Clusters of furuncle with necrosis of skin and subcutaneous tissue Carbuncle • Burning charcoal • Clusters of furuncle – Bacterial infection • Streptococcus pyogenes , Staphylococcus aureus • Nape of neck Risk factors • Diabetes • Elderly • Immunocompromised • Poor hygiene • Poor nutrition Common sites • Hairy areas • Nape of neck • Axilla • Back and shoulder • Coarse skin with less vascularity Evolution • Infection • Vesicles in sieve like pattern • Red indurated skin discharging pus • Fuse together to form a central necrotic ulcer surrounded by fresh peripheral vesicles – cribriform appearance • Centre becomes black – cutaneous vessel occlusion • Spreads to surrounding skin • Systemic symptoms – sick patient, ketosis Features • Pain and stiffness • Induration of skin and subcutaneous tissue • Size – pea to golf ball …. • Red/ dusky, multiple vesicles, discharging pus – cribriform appearance Carbuncle Carbuncle Investigations • Urine – Sugar, ketones • Blood – Sugar • Pus for culture Treatment • General – Diabetic control • Local hot compress • Antibiotics • Surgical treatment – Large size or pus formation • Incision and drainage – Wound debridement Saucerisation Saucerisation CARBUNCLES • C – cribriform pattern • A - aureus • R – red hot charcoal • B – boils initially • U – uncontrolled diabetes • N – neck • C – cruciate incision • L – large crateriform ulcer • E – excision • S – subcutaneous fat necrosis Skin abscess Incision and drainage