Surgical Infections Lecture 2 PDF

# Skin and Soft-tissue Infections ## Cellulitis - Diffuse inflammation of connective tissue (dermal and s/c layers of the skin) - Skin on the face or lower legs are most commonly affected - Caused by normal skin flora or by exogenous bacteria (Group A streptococci) - Bacteria inoculated beneath t...

# Skin and Soft-tissue Infections ## Cellulitis - Diffuse inflammation of connective tissue (dermal and s/c layers of the skin) - Skin on the face or lower legs are most commonly affected - Caused by normal skin flora or by exogenous bacteria (Group A streptococci) - Bacteria inoculated beneath the skin, defensive barriers are easily breached by the toxins released by streptococci, lymphatic system involved. ## Predisposing Factors - Cracks in the skin (dry skin, eczema, tattoos), - Cuts, - Blisters, - Burns, - Insect bites, - Animal bite, - Surgical wounds, - Sites of intravenous catheter insertion, - Injecting drugs, - Pregnancy, diabetes and obesity, chronic venous insufficiency and varicose veins which can affect circulation - Break in the skin does not need to be visible. ## Diagnosis - Most often a clinical diagnosis - Local cultures do not always identify the causative organism. - Blood cultures usually are positive only if the patient develops generalized sepsis. **Conditions that may resemble cellulitis include:** - Deep vein thrombosis: investigate by leg ultrasound - Stasis dermatitis, which is inflammation of the skin from poor blood flow. - Lymes disease ## Treatment - Resting the affected limb or area - Cleaning the wound site if present (with debridement of dead tissue if necessary) - Oral antibiotics, but in severe cases admission and IV antibiotics - Flucloxacillin - Benzylpenicillin - Ampicillin/amoxicillin - Pain relief is also often prescribed, but excessive pain should always be considered relevant, as it is a symptom of necrotising fasciitis, which requires emergency surgical attention. - Hyperbaric oxygen can be a valuable adjunctive therapy, but is not widely available ## Cellulitis - A photo showing the leg of a person affected by cellulitis. The left leg is normal whereas the right leg shows swelling and inflammation. # Skin and Soft-tissue Infections ## Erysipelas - An acute steptococcal infection of the more superficial dermis (upper subcutaneous dermis) resulting in inflammation. - Has a well defined edge Erysipelas and cellulitis often coexist, so it is often difficult to make a distinction between the two. ## Risk Factors - This disease is most common among the elderly, infants, and children. - People with immune deficiency, diabetes, alcoholism, skin ulceration, fungal infections and impaired lymphatic drainage (e.g., after mastectomy, pelvic surgery) are also at increased risk. ## Erysipelas in a Surgical Incised Wound - A photo showing the affected area of a surgical wound on a person affected by erysipelas. - The wound shows swelling, redness and inflammation. ## Skin and Soft-tissue Infections (Erysipelas) - A close up view of the skin of a person affected by erysipelas. - The skin shows inflammation and redness. ## Erysipelas - A close up view of the face of a person affected by erysipelas. - The face shows erysipelas around the nose. ## Erysipelas - A photo showing a leg of a person affected by erysipelas. ## Erysipelas - An image showing a profile view of a man's face. The face shows erysipelas around the nose. ## Signs and Symptoms - Constitutional symptoms including high fevers, shaking chills, fatigue, headaches, vomiting - Erythematous skin lesion enlarges rapidly and has a sharply demarcated raised edge (red, swollen, warm, hardened and painful rash, similar in consistency to an orange peel). - More severe infections can result in vesicles, bullae, and petechiae, with possible skin necrosis. - Lymph nodes may be swollen, and lymphedema may occur. Occasionally, a red streak extending to the lymph node can be seen - Face, arms, fingers, legs and toes are commonly affected. - Fat tissue is most susceptible to infection, and facial areas typically around the eyes, ears, and cheeks. - Repeated infection of the extremities can lead to chronic swelling (lymphadenitis). ## Etiology - Most cases of erysipelas are due to Streptococcus pyogenes (also known as beta-hemolytic group A streptococci) ## Diagnosis - Appearance of well-demarcated rash and inflammation. - Blood cultures are unreliable - Erysipelas can be distinguished from cellulitis by its raised advancing edges and sharp borders. - Elevation of the antistreptolysin O titre occurs after around 10 days of illness. ## Complications - Spread of infection to other areas of body through the bloodstream (bacteremia), including septic arthritis and infective endocarditis (heart valves). - Septic shock - Recurrence of infection - Erysipelas can recur in 18-30% of cases even after antibiotic treatment. - Lymphatic damage - Necrotizing fasciitis A potentially-deadly exacerbation of the infection if it spreads to deeper tissue - Death ## Treatment - Oral or preferably intravenous antibiotics - Penicillin - Clindamycin - Erythromycin - Cephalosporins - Symptoms resolve in a day or two, the skin may take weeks to return to normal. - Because of the risk of reinfection, prophylactic antibiotics are sometimes used after resolution of the initial condition. ## Prevention - Wound cleaned and dressed appropriately - Changing bandages daily - Retained foreign bodies removed ## Erysipelas and Cellulitis - Erysipelas and cellulitis are skin infections, but erysipelas typically has well-defined borders and affects the upper skin layers, causing a raised, red rash. - Cellulitis has less distinct borders and can affect deeper tissues. - If you notice a raised rash with clear edges, it's more likely erysipelas. # Life Threatening Surgical Infections # Skin and Soft-tissue Infections... Necrotising Infections ## Synergistic gangrene - Chronic progressive bacterial gangrene is caused by the synergistic action of streptococci and staphylococci. - The incubation period is 7 to 14 days. - Cellulitis is followed by gangrenous ulceration that is progressive unless treated. ## Treatment - Radical excision of the ulcerated lesion - Large systemic doses of penicillin. ## Skin and Soft-tissue Infections (Synergistic gangrene) - A photo showing the leg of a man affected by skin and soft tissue infections. - The leg shows a deep ulceration. ## Synergistic Gangrene - A man laying on a bed. The leg shows a large, open ulceration. ## Gas gangrene - Anaerobic infection of muscle by Clostridium perfringens which multiply in the presence of devitalized muscle. It produces a variety of potent toxins, including hyaluronidase, collagenase, four different hemolysins, five necrotizing lecithinases, and six other lethal necrotizing toxins which destroy tissue and blood cells. - Disruption and fragmentation of normal muscle cells and capillaries result in further necrosis, hemorrhage, and edema. The affected muscles are at first red and friable, but progress to a purplish black. - The presence of gas is variable. The affected area swells and discharges a brownish, malodorous fluid. - The overlying skin initially shows blotchy ecchymoses (marbling), then blackens, and finally sloughs. ## Gas gangrene - A photo showing the foot of a man affected by gas gangrene. The foot shows swelling and ulceration. ## Gas gangrene - The diagnosis of gas gangrene is based on typical clinical findings, as well as on the presence of large, Gram-positive rods in the wound fluid. - Delay in diagnosis greatly increases the mortality. - Immediate removal of involved muscle groups is necessary: amputation is indicated if the remaining viable muscles are insufficient for useful function. - High intravenous doses of penicillin and whole blood are given preoperatively and postoperatively. Multiple treatments with hyperbaric oxygen (oxygen at 3.03 kPa) may reduce the amount of debridement necessary and lower the mortality, but muscle resection should not be delayed in anticipation of hyperbaric therapy. - Untreated gas gangrene is always fatal; the fatality rate in treated patients ranges from 25 to 40 per cent. ## Necrotising Fasciitis ## Necrotizing fasciitis - This is a serious mixed infection due to hemolytic streptococci or staphylococci and peptostreptococci (streptococcal pyogenic exotoxins). - Associated with excessive collagenase production, leading to dissolution of connective tissue. They cause the destruction of skin and muscle by releasing toxins - The infection involves the epifascial tissues of an operative wound, laceration, abrasion, or puncture. - It may be immediately fulminant or may remain dormant for six or more days before beginning to spread rapidly. ## Symptoms - Intense pain at the site of infection - Tissue becomes swollen, often within hours. In the early stages, signs of inflammation may not be apparent if the bacteria are deep within the tissue. - If they are not deep, signs of inflammation such as redness and swollen or hot skin show very quickly. - Skin color may progress to violet and blisters may form, with subsequent necrosis (death) of the subcutaneous tissues. - Diarrhea and vomiting are also common symptoms. - Fever and patients appear very ill. - Mortality rates have been noted as high as 73 percent if left untreated ## Treatment - Patients will require monitoring in an intensive care unit. - Aggressive surgical debridement (removal of infected tissue). excision of the entire area of fascia affected... Typically, this leaves a large open wound which often requires skin grafting. - Amputation of the affected organ(s) may be necessary. - administration of large doses combination of intravenous antibiotics including penicillin, vancomycin and clindamycin - Mortality rates :73 percent if left untreated ## Management of Necrotising Infections ### Antibiotic rationale - These infections are serious and life-threatening; it is therefore important to administer IV antibiotics in high doses to quickly achieve bactericidal concentrations in the affected tissue ### Empirical therapy - Empirical therapy must be comprehensive and cover all likely pathogens, including aerobes and anaerobes and must always be an adjunct to and not a substitute for surgery. A broad -spectrum beta-lactam antibiotic should be used, together with an antibiotic that is active against anaerobes. ### Empirical therapy - Examples of empirical antibiotic regimens include: - A broad-spectrum penicillin such as amoxicillin plus metronidazole plus an aminoglycoside such as gentamicin. - A second-generation cephalosporin such as cefuroxime, plus metronidazole. - Penicillin-allergic : clindamycin plus a quinolone eg. ciprofloxacin. - If the patient is immunocompromised then pseudomonal infection is also common and a quinolone should be used. ## Prognosis (Mortality) | Variable (On Admission) | No. of Points | |:--:|:--:| | Heart rate > 110 beats/min | 1 | | Temperature <36°C | 1 | | Creatinine >1.5 mg/dL | 1 | | Age >50 yr | 3 | | White blood cell count >40,000 | 3 | | Hematocrit >50 | 3 | | Group Categories | No. of Points | Mortality Risk | |:--:|:--:|:--:| | 1 | 0-2 | 6% | | 2 | 3-5 | 24% | | 3 | 26 | 88% | *From Anaya DA, Bulger EM, Kwon YS, et al: Predicting mortality in necrotizing soft tissue infections: A clinical score. Paper presented at the 25th Annual Meeting of the Surgical Infection Society and the 2nd Joint Meeting with the Surgical Infection Society-Europe, Miami, 5-7, 2005, Miami.*