Antimicrobial therapy surgical infections

Brain abscesses are localized collections of pus within the cranium. These infections are difficult to treat due to the presence of walled-off infections in the brain tissue that are hard for some antibiotics to reach. In addition to appropriate antimicrobial therapy (a discussion of which is beyond the scope of this chapter), surgical debridement is often required as an adjunctive measure. Surgical debridement also may be required in the management of neurosurgical postoperative infections. 

Surgical intervention has become an integral therapy in combination with pharmacologic management of IE. Valve replacement is the predominant intervention, and it is used in a minimum of 25% for all cases of IE.1 Surgery may be indicated if the patient has unresolved infection, ineffective antimicrobial therapy (often associated with fungal IE), more... 

The treatment of intraabdominal infection most often requires the coordinated use of three major modalities (1) prompt drainage, (2) support of vital functions, and (3) appropriate antimicrobial therapy to treat infection not eradicated by surgery. Antimicrobials are an important adjunct to drainage procedures in the treatment of secondary intraabdominal infections however, the use of antimicrobial agents without surgical intervention usually is inadequate. For most cases of primary peritonitis, drainage procedures may not be required, and antimicrobial agents become the mainstay of therapy. 

Mazuski JE, Sawyer RG, Nathens AB, et al. The Surgical Infection Society guidelines on antimicrobial therapy for intraabdominal infections An executive summary. Surg Infect 2002 3 161-174. 

Treatment of osteomyelitis is dependent on the extent of bone necrosis. For acute osteomyelitis with minimal bone destruction, an extended course of antimicrobial therapy should effectively treat the infection however, in chronic osteomyelitis surgical intervention is also typically required. 

Cefazolin or cefuroxime are appropriate for prophylaxis in cardiothoracic and vascular surgeries. In the case of 3-lactam allergy, vancomycin or clindamycin are advised. Debate exists on the duration of antimicrobial prophylaxis. The National Surgical Infection Prevention Project cites data that extending prophylaxis beyond 24 hours does not decrease SSI rates and may increase bacterial resistance.1 American Society of Health-System Pharmacists guidelines from 1999 allow for the continuation of prophylaxis for up to 72 hours.22 Duration of therapy should be based on patient factors and risk of development of an SSI. SSIs are rare after cardiothoracic operations, but the potentially devastating consequences lead some clinicians to support longer periods of prophylaxis. 

Other host factors are related to the necessity for surgical drainage of abscesses or removal of foreign bodies and/or necrotic tissue. If these situations are not corrected, they result in persistent infection and, occasionally, bacteremia, despite adequate antimicrobial therapy. 

The three major modalities for the treatment of intraabdominal infection are prompt surgical drainage, support of vital functions, and appropriate antimicrobial therapy to treat infection not removed by surgery. 

Typically, they are used in surgical procedures associated with an infection rate that exceeds 5%. The risks of the prophylactic antimicrobial therapy must be less than the risk and consequences of infection. 

The goal of therapy of acute bacterial cellulitis is rapid eradication of the infection and prevention of further complications. Antimicrobial therapy of bacterial cellulitis is directed against the type of bacteria either documented or suspected to be present based on the clinical presentation. Local care of cellulitis includes elevation and immobilization of the involved area to decrease swelling. Cool sterile saline dressings can decrease pain and can be followed later with moist heat to aid in localization of the cellulitis. Surgical intervention (incision and drainage) as a mode of therapy is rarely indicated in the treatment of cellulitis. 

Further common postoperative complications include superficial wound infection or deep sternal infection (retrosternal infection - mediastinitis). Prophylactic antimicrobial therapy should therefore be routinely employed. Deep wound infection in an inununocompromised patient always indicates a life-threatening situation and requires both extensive surgical intervention and aggressive antimicrobial therapy. 

Raymond et al. reported on a rotation study in a surgical intensive care unit with a different twist.Patients were stratified as either having sepsis/peritonitis or pneumonia, and empiric therapy was cycled every 3 months by syndrome. Fourteen hundred fifty-six admissions and 540 infections were treated over a 2-year period. With similar severity of illness during the before and after periods (mean APACHE II = 19), the authors demonstrated a reduction of length of stay from a mean of 62 days to 39 days, a reduction of vancomycin-resistant enterococcal and methicillin-resistant staphylococcal infection from 14 per 100 admissions to 8 per 100 admissions and death due to any cause dropped from 25 in the before period to 18 in the rotation period. Antimicrobial susceptibility and several other key parameters needed to evaluate the effectiveness of this program were not reported. 

Whichever antimicrobial regimen is chosen, the patient should be reassessed continually to determine the success or failure of therapies. The clinician should recognize that there are many reasons for poor patient outcome with intraabdominal infection improper antimicrobial administration is only one. The patient may be immunocompromised, which decreases the likelihood of successful outcome with any regimen. It is impossible for antimicrobials to compensate for a nonfunctioning immune system. There may be surgical reasons for poor patient outcome. Failure to identify all intraabdominal foci of infection or leaks from a GI anastomosis may cause continued intraabdominal infection. Even when intraabdominal infection is controlled, accompanying organ system failure, most often renal or respiratory, may lead to patient demise. 

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