Surgical site infections, abbreviated SSIs, are common complications of surgical procedures and account for one of the most common causes of healthcare associated infections. CDC estimated an annual incidence of greater than 150,000 SSIs occurred in US acute care hospitals in 2011, for the 10 procedures reportable through the National Health Care Safety Network or NHSN. Although considerable, improvement in rates has been made over the last few years, SSIs are still associated with an increase in hospital length of stay and readmission rates. Antimicrobial prophylaxis for surgical procedures is the primary intervention employed to reduce SSI rates. Here, we will review the general surgical antimicrobial guidelines and identify opportunities to incorporate antimicrobial stewardship principles into surgical prophylaxis. The majority of these general recommendations are derived from the recently revised clinical practice guidelines for antimicrobial prophylaxis in surgery from the American Society of Health System Pharmacist, which is included in the reference list at the end of this module. These guidelines, published in 2013, were developed jointly among several professional organizations, including Health System Pharmacists, The Infectious Diseases Society of America, the Surgical Infection Society, and the Society for Healthcare Epidemiology of America. Anti-microbial prophylaxis is an important component of quality improvement initiatives, such as those outlined in the Surgical Care Improvement Project, better known as SCIP. As previously discussed, the main principles of stewardship are giving the right drug at the right dose via the appropriate means of delivery with special attention to duration and deescalation, or the five Ds, all of which are applicable to surgical antimicrobial prophylaxis; but for the moment, we'll leave aside delivery since the majority of patients will be receiving intravenous antimicrobials before their surgical procedures. Please note that prophylactic antibiotics for clean and clean contaminated procedures are justified in most instances while antibiotics for dirty procedures or surgical procedures in the face of known infection are considered treatment not prophylaxis. Let's consider the first two Ds: drug and dose. SSI prevention falls into the category of antibiotic prophylaxis. As with any prophylactic regimen, one of the first considerations is selecting an agent that covers the likely pathogens for a surgical site, such as covering gram-negatives and anaerobes for abdominal surgery and gram-positives for orthopedic operations. A second important consideration, and this relates mostly to dosing, is achieving adequate tissue levels of the drug. This can be accomplished by following dosing recommendations and using weight-based dosing for obese patients when necessary. As far as the third D, duration; typically, in stewardship, we think of this as giving a drug for the appropriate length of time to treat an identified infection but not too long to risk engendering resistance. Duration in SSI prevention is focused on achieving adequate drug levels for the duration of the surgical procedure. Antibiotics should be given before the incision or before the inflation of a tourniquet for procedures in which that is used. A general rule is that an antibiotic should be re-dosed for any procedure that lasts longer than two drug half-lifes for your prophylactic agent. Re-dosing may also be warranted for shorter cases that involve significant blood loss. When thinking about deescalation and the prevention of SSIs, it is most important to think about using the narrowest spectrum for the likely pathogens as discussed earlier. Also, there is evidence that single dose or less than 24 hours of antibiotics is sufficient for SSI prevention. Several other considerations that factor into antimicrobial decisions for surgical prophylaxis reinforce stewardship principles. For example, beta-lactam antibiotics are some of the most commonly used prophylactic agents. As discussed in the module on antibiotic allergies, it is essential to characterize the history of a patient's reaction to determine the risk of subsequent drug exposure. Skin testing may be helpful, but is not 100 percent predictive of cross-reactivity. For elective surgical procedures, the risk of an antibiotic allergy could be assessed in the pre-surgical evaluation. Alternatives to beta-lactams exist and should be selected to maximize desired spectrum of coverage in the context of the plan procedure. And with the knowledge that some agents may not be as effective as routine prophylactic agents, local antibiogram data may be referenced to minimize unnecessarily broad coverage. Another consideration is to limit additional coverage. A single agent is often sufficient for prophylaxis. In cases where a patient may have an ongoing infection unrelated to the plan surgical procedure, it's best to postpone the surgery until the other side of infection is resolved. If a time delay is not possible, then the selected prophylactic regimen should include coverage for the ongoing infection. Other considerations also include non anti-microbial factors that help prevent SSIs. Antibiotics are only one method of preventing SSIs. Attention to basic infection control practices, such as instrument sterilization, operating room, environmental cleaning and appropriate skin preparation also have an important role in SSI prevention. Additionally, physiologic parameters, such as appropriate temperature and glycaemic control are essential for SSI prevention. Finally, there are patient-specific factors that can influence the risk for SSIs. Discussion of these topics is beyond the scope of this course.