Prophylactic administration of antimicrobials prior to surgery has been recommended for decades to reduce the risk of surgical site infections (SSIs). The Guideline for Prevention of Surgical Site Infection, 1999, available through the Centers for Disease Control (CDC), includes antimicrobial prophylaxis as an evidence-based recommendation for reducing infection risk. Specifically, the guidelines describe antimicrobial prophylaxis as a timed adjunct used to decrease the microbial burden of intraoperative contamination to a level that will not overwhelm host defenses. Additional CDC recommendations are included in Table 1.1

In addition to the CDC guidelines for reducing SSIs, study reports and consensus panels have expanded information about the use of prophylactic antimicrobials including details about the optimal timing of administration. In 2004 Bratzler and colleagues from the National Surgical Infection Prevention Project published an advisory statement about antimicrobial prophylaxis in which the following recommendations were made in a consensus statement:2

•For the duration of the operation, serum and tissue antimicrobial levels should exceed the minimum inhibitory concentrations (MICs, or kill times) for the organism likely to be encountered.

•Infusion of the first antimicrobial dose should begin within 60 minutes before incision (or 120 minutes when a fluoroquinolone or vancomycin in used).

•For most operations, antimicrobial prophylaxis should end within 24 hours after the operation; for cardiothoracic surgery, prophylaxis should be continued for up to 72 hours after the operation.

•Prolonged use of prophylactic antimicrobials is associated with the emergence of resistant bacteria.

Quality measures for reduction
of SSIs
The objective of the National Surgical Infection Prevention Project, which was implemented by the Centers for Medicare and Medicaid Services and the CDC, is to decrease morbidity and mortality associated with postoperative SSIs. In addition to the specific recommendations for antimicrobial prophylaxis, three performance measures for national surveillance and quality improvement were developed, including:2

1.The proportion of patients who receive parenteral antimicrobial prophylaxis within 1 hour before surgical incision.

2.The proportion of patients who receive an antimicrobial agent that is consistent with published guidelines.

3.The proportion of patients whose prophylactic antimicrobial therapy is discontinued within 24 hours after surgery.

These performance measures were designed to provide a method of quality monitoring for commonly performed surgeries for which antimicrobial prophylaxis typically is recommended, such as coronary artery bypass grafting and other open-chest cardiac surgery (excluding transplantation), vascular surgery, abdominal colorectal surgery, hip and knee arthroplasty, and hysterectomy.2

Results of national surveillance
After publication of the evidence-based prophylactic guidelines and quality measures, Bratzler and colleagues conducted a retrospective study of 2,965 acute-care hospitals in the United States to determine whether the recommendations of the National Surgical Infection Prevention Project were adopted.3 The use of antimicrobial prophylaxis was evaluated by medical record review of a random sample of 34,133 Medicare inpatients undergoing the same types of commonly performed operations used to establish the quality measures. The time period of the record review was from January 1 through November 30, 2001. The endpoints of the study were adherence to each of the three quality measures.

Results for initiation and discontinuation of antimicrobial prophylaxis are presented in Figure 1. Most patients (55.7%) received an initial antimicrobial dose within an hour before incision, but less than half (40.7%) had their antimicrobial therapy discontinued within the recommended 24 hours after the end of surgery. The study also found that nearly 10% of patients did not receive the initial antimicrobial dose until four hours after surgery had begun; this is significant because initiation of antimicrobials after surgery has started does not produce adequate preventive benefit. Failure to discontinue antimicrobials within 24 hours after surgery contributes to resistance and adds unnecessary expense. The second quality measure, use of an antimicrobial agent that is consistent with published recommendations, was followed in 92.6% of cases. Study investigators concluded that there are substantial opportunities to improve the use of prophylactic antimicrobials.3

Consequences
Patients who develop SSIs are 60% more likely to be admitted to the intensive care unit, five times more likely to be readmitted to the hospital, and twice as likely to die compared to patients without infections. In addition to the negative consequences on patients health, costs of care are also increased by SSIs.3,4 Hospital multidisciplinary review committees can reduce the incidence of SSIs by following the evidence-based guidelines on antimicrobial prophylaxis. Although no cost analysis has been published regarding the implementation of the guidelines, cost outcomes would most likely be very positive. The primary actions needed are earlier initiation and discontinuation of antimicrobials. It is conceivable that earlier discontinuation would decrease direct costs of the antimicrobial agent. Regardless, reduction in SSIs alone would provide substantial cost savings while improving patient outcomes.

Conclusion
Evidence-based guidelines for antimicrobial prophylaxis are known to reduce the incidence of SSIs. Nevertheless, the timing of administration is not optimal for a substantial number of patients. Adhering to the three quality measures identified for reduction of SSIs could reduce patient morbidity and mortality and decrease the costs of case associated with SSIs. HPN

References
1.Mangram AJ, Horan TC, Pearson ML, Silver LC, Jarvis WR. Guideline for prevention of surgical site infection, 1999. Hospital Infection Control Practices Advisory Committee. Infect Control Hosp Epidemiol. 1999;20(4):250-278.

2.Bratzler DW, Houck PM; Surgical Infection Prevention Guidelines Writers Workgroup. Antimicrobial prophylaxis for surgery: an advisory statement from the National Surgical Infection Prevention Project. Clin Infect Dis. 2004;38(12):1706-1715.

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.Kirkland KB, Briggs JP, Trivette SL, Wilkinson WE, Sexton DJ. The impact of surgical-site infections in the 1990s: attributable mortality, excess length of hospitalization, and extra costs. Infect Control Hosp Epidemiol. 1999;20(11):725-730.