Infections occur in approximately 3 to 5 percent of traumatic wounds repaired in emergency departments, although this rate varies widely according to mechanism, location, and patient factors.17,,8,! 1 and 12 Delays of over 3 h in seeking care, wound location, extremes of age, crush injuries, puncture or avulsion wounds, retained foreign bodies, and contamination with saliva, feces, and soil are all risk factors for infection. Delays of over 3 h in seeking care allow bacterial proliferation to increase exponentially. Less vascular areas, moist areas (axilla and perineum), and exposed areas (feet and hands) also tend to be at higher risk for infection. Crush or puncture wounds are more prone to infection due to the tensile and compressive forces generated that increase the potential for devitalized tissue. Additionally, wounds contaminated with saliva or feces are at risk. Soil may increase infection by direct interference with leukocyte function.
To reduce the incidence of wound infections, antibiotics have been commonly used for years, although there is no clear evidence that antibiotic prophylaxis prevents wound infections in most patients whose wounds are closed in the ED.12 Antibiotic prophylaxis has been studied and well accepted in some surgical procedures. The principles learned from these studies are that effectiveness requires the achievement of antimicrobial blood levels prior to or rapidly after wound contamination, and there is no benefit for continuing antibiotics past 24 h in most cases.1 1 and 15 The common practice of giving a patient a prescription for an oral cephalosporin for 7 days upon discharge, which the patient may not fill for hours, clearly fails to meet these principles. If used, antibiotic prophylaxis for traumatic wounds in an emergency department should be (1) started rapidly, ideally within 1 h and before significant tissue manipulation; (2) performed with agents that are effective against predicted pathogens; and (3) administered by routes that rapidly achieve desired blood levels. For most circumstances, this will require intravenous broad-spectrum or combination antibiotic regimens. Oral administration, though theoretically less effective, may also work if done in the emergency department before manipulation and by using an agent with appropriate spectrum and rapid oral absorption.
The most important step in prevention of a wound infection is adequate irrigation and debridement.
Current literature does not support the routine use of antibiotics for most wounds encountered in emergency departments.12 However, in wounds contaminated by debris or feces, or caused by punctures or bites, in wounds with tissue destruction or in avascular areas, and in neglected wounds, sufficient bacteria may be present to cause infection, and antibiotics are often administered. If antibiotics are chosen, and since most wound infections are due to staphylococci or streptococci, a penicillinase-resistant penicillin (e.g., dicloxacillin) or a first-generation cephalosporin (e.g., cephalexin) provides reasonable coverage. For dog, cat, and human bites, penicillin should be added to cover both Pasteurella and Eikenella, respectively. Alternatively, amoxicillin-clavulanate alone can be used for therapy in bite wounds but is a more expensive alternative. There is no proven benefit, though, for antibiotic prophylaxis of low-risk dog-bite wounds. 1 l6 Full-thickness oral lacerations also warrant antibiotics and should be treated with penicillin.17 Wounds contaminated by freshwater, and plantar puncture wounds through athletic shoes, should include Pseudomonas coverage, preferably with a fluoroquinolone.
The duration for antibiotic prophylaxis is unknown; most physicians use 5 to 7 days. Patients with established wound infections usually require longer treatment. A wound warranting antibiotics can be reevaluated at 24 to 48 h, or patients should be given clear instructions to return at the earliest sign of infection. Contaminated wounds, or those with undetected foreign bodies, may still develop infection despite antibiotic prophylaxis.
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