AAOS Bulletin - June, 2005

Selecting an appropriate prophylactic antibiotic agent

Reduce surgical site infections with appropriate prophylactic antibiotic use

By Laura J. Prokuski, MD

Surgical site infections are a major source of postoperative illness, accounting for nearly 25 percent of all nosocomial infections in the United States each year. The Centers for Disease Control and Prevention (CDC) estimate that approximately 500,000 surgical site infections occur annually in the United States.1

The National Surgical Infection Prevention Project (SIPP) was initiated in August 2002 as a joint venture between the Centers for Medicare and Medicaid Services and the CDC. By promoting the appropriate selection, timing and duration of administration of prophylactic antibiotics, SIPP seeks to reduce the morbidity and mortality related to postoperative infections in the Medicare population.2

Preliminary data from this project indicates that antibiotic prophylaxis is not always administered in a manner that is supported by scientific evidence.3 Inappropriate use of antibiotics does not prevent postoperative infections, but contributes to antibiotic resistance, increases the risk of adverse reactions, predisposes the patient to infections and increases healthcare costs.

Antibiotics in orthopaedic surgery

Prophylactic antibiotics reduce the incidence of infection after elective orthopaedic surgery. The use of prophylactic antibiotics is considered routine in major orthopaedic procedures such as arthroplasty, spine surgery and fracture repair. The goal of antimicrobial prophylaxis is to prevent intraoperative contamination of the wound by the most probable organisms to be encountered for the particular type of operation.

Optimal prophylaxis ensures that adequate concentrations of an appropriate antibiotic are present in the serum, tissue and wound during the entire time that the surgical wound is open and at risk for bacterial contamination. The antibiotic that is used should be active against bacteria that are likely to contaminate the wound and should be both safe and inexpensive. The selection of antibiotic prophylaxis should have the smallest impact possible on the normal bacterial flora of the patient and the biogram of the institution.4

The primary bacteria of concern in clean orthopaedic surgery are organisms found on the skin, primarily Staphylococcus aureus and Staphylococcus epidermidis. A first-generation cephalosporin, such as cefazolin, can provide adequate coverage against the majority of staphylococci and other gram-positive bacteria by inhibiting cell wall synthesis. Second-generation cephalosporins, such as cefuroxime, have a slightly broader spectrum, covering some gram-negative bacteria while remaining efficacious against gram-positive organisms.

Currently, cefazolin or cefuroxime are the preferred antibiotics used for prophylaxis in patients undergoing elective orthopaedic procedures.4,5 Both cover the most common contaminating skin organisms and have a long enough half life to provide adequate tissue concentrations over the majority of orthopaedic procedures. Adverse effects are rare, but include rash and anaphylaxis.

A careful history of prior drug allergies should be obtained before surgery. A number of studies have demonstrated that the incidence of true drug allergy is lower than recorded in medical records. For some, formal allergy testing may disprove a questionable allergy and allow the use of recommended cephalosporins for surgical prophylaxis. For those with confirmed -lactam allergy or serious adverse event with prior administration of penicillin or a cephalosporin, clindamycin or vancomycin may be used as prophylactic agents.5

Vancomycin use

Vancomycin should not routinely be used for surgical prophylaxis. Some surgeons justify the use of vancomycin for surgical prophylaxis because an institution has a high level of methicillin-resistant staphylococcus surgical site infections. However, there is no consensus about what constitutes “high” levels of methicillin- resistance in an institution, and no threshold exists that can support the use of vancomycin prophylaxis routinely in this situation.4,5 A decision to use vancomycin in this scenario should involve studies of surgical site infection rates for a particular operation and specific infecting organisms, as well as a review of infection prevention practices for compliance and consultation with infectious disease experts.5

Vancomycin should be reserved for the treatment of serious infections with -lactam-resistant organisms and for treatment of infections in patients with a true -lactam allergy. Vancomycin may be used for surgical prophylaxis in patients with known colonization with methicillin-resistant Staphylococcus aureus (MRSA) and with true allergy to -lactam antimicrobials.4,5

The AAOS Advisory Statement “The Use of Prophylactic Antibiotics in Orthopaedic Medicine and the Emergence of Vancomycin-Resistant Bacteria” provides additional information on the appropriate use of vancomycin and steps to reduce the nosocomial spread of staphylococci and enterococci. It is available online.

Summary

The antibiotic used for prophylaxis should be carefully selected, consistent with current recommendations in the literature and take into account the issues of resistance and patient allergies. The ideal prophylactic agent is effective against microorganisms at the surgical site. Effective antimicrobial prophylaxis is dependent on adequate concentrations of the drug in tissues throughout the entire procedure. Routine use of vancomycin as a prophylactic agent should be avoided.

The AAOS Advisory Statement on “Recommendations for the Use of Intravenous Antibiotic Prophylaxis in Primary Total Joint Arthroplasty” provides additional information on the appropriate selection, timing and duration of prophylactic agents for total joint arthroplasty. It is available online.

Laura J. Prokuski, MD, is assistant professor in the department of orthopaedics and rehabilitation at the University of Wisconsin Medical School and a member of the AAOS Infections Committee. She can be reached at prokuski@orthorehab.wisc.edu

References:

1. Wong ES: Surgical site infections. In: Mayhall DG, editor. Hospital Epidemiology and Infection Control 2nd Ed. Philadelphia; Lippincott; 1999, p 189-210.

2. http://www.surgicalinfectionprevention.org

3. Bratzler DW, Houck PM, Richards C, et al: Use of antimicrobial prophylaxis for major surgery: Baseline results from the National Surgical Infection Prevention Project. Arch Surg 2005;140(2):174-182.

4. Raymond DP, Kuehnert MJ, Sawyer RG. Preventing antimicrobial-resistant bacterial infections in surgical patients. Surg Infect 2002;3(4): 375-385.

5. Mangram AJ, Horan TC, Pearson ML, Silver LC, Jarvis WR. Guidelines for preventing surgical site infections. Am J Inf Control 1999;27(2): 97-132


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