Infection at or near surgical incisions within 30 days of an operative procedure, dubbed surgical site infection, contributes substantially to surgical morbidity and mortality each year. Surgical site infection (SSI) accounts for 15% of all nosocomial infections and, among surgical patients, represents the most common nosocomial infection.¹ Postsurgical infection leads to increased length of postoperative hospital stay, drastically escalated expense, higher rates of hospital readmission, and jeopardized health outcomes. Accordingly, the first step in the treatment of SSIs is in their prevention. This encompasses meticulous operative technique, timely administration of appropriate preoperative antibiotics, and a variety of preventive measures aimed at neutralizing the threat of bacterial, viral, and fungal contamination posed by operative staff, the operating room environment, and the patient’s endogenous skin flora. It is this latter aspect of contamination, and specifically mechanical methods of prevention, on which this review focuses.

Definition of SSI

There are 3 different types of surgical site infection defined by the Centers for Disease Control and Prevention (CDC).² In the criteria put forth by the CDC, SSIs are classified as either incisional or organ/space, with incisional SSIs being further subclassified as superficial (involving only skin and subcutaneous tissue) versus deep (involving underlying soft tissue).The Risks Of Surgical Site Infection Among Patients With Abdominal Surgeries Essay.  Table 1 further elaborates on the CDC classification system, which has been widely adopted by surveillance and surgical personnel.

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Cost of SSIs

Surgical site infections raise costs due to prolonged hospitalization, additional diagnostic tests, therapeutic antibiotic treatment, and, rarely, additional surgery.³ In 2009, it was estimated that SSI extended the length of hospital stay on average by 9.7 days and increased costs by $20,842 per admission; this amounts to additional hospital costs exceeding $900 million, with hospital readmission due to SSI accounting for an additional $700 million in health care spending.⁴ Deep SSIs tend to raise costs more than superficial infection.⁵ A recent study synthesizing the results of 16 various studies examining the cost of SSIs revealed a mean increase of 115% for the cost of care of a patient with an SSI as compared with noninfected control subjects.⁶

Microbiology

In the majority of SSI cases, the pathogen source is the native flora of the patient’s skin, mucous membranes, or hollow viscera.⁷ When skin is incised, underlying tissue is exposed to overlying endogenous flora.⁸ Most typically, aerobic gram-positive cocci such as Staphylococcus serve as the contaminant, with resistant pathogens such as methicillin-resistant S aureus (MRSA) representing an increasing proportion of such infections in recent years.^9,10 Entry into hollow viscera exposes surrounding tissue to gram-negative bacilli such as Escherichia coli, gram-positive organisms such as enterococcus, and, occasionally, anaerobes such as Bacillus fragilis.² Yeast species and viral pathogens also pose a risk.¹¹ In rare cases in which an unusual pathogen is identified in an outbreak cluster, an epidemiologic investigation should be conducted to rule out a focal contamination source, such as colonized surgical personnel, contaminated bandages, contaminated disinfectant solutions, or other such niduses.^12–15 Table 2 further expands upon various surgical procedures and the most common pathogens encountered in the surrounding tissues.²

Patient Risk Factors

Several patient characteristics have been shown to have a significant, independent association for SSI prediction. These include, but are not limited to, diabetes, cigarette smoking, obesity, and coincident remote site infections or colonization.² Although the contribution of diabetes to SSI remains controversial, significant relationships have been demonstrated between elevated hgA_1c level and SSI rates, as well as postoperative serum glucose levels higher than 200 mg/dL in cardiac surgery populations.¹⁶ Moreover, obesity poses an independent risk for SSI separate from its association with diabetes.^1,17 Cigarette smoking interferes with primary wound healing, possibly secondary to constriction of peripheral blood vessels, leading to tissue hypovolemia and hypoxia.^18,19 Consistent with these findings, in 2003, a randomized, controlled trial demonstrated abstinence from smoking for as little as 4 weeks significantly reduces incisional wound infections.²⁰ S aureus colonization, found in the nares of 20% to 30% of healthy humans, has been strongly implicated as a predictor of SSI involving this organism.^21,22 In a 2008 Cochrane Database review, analysis of 8 randomized, controlled trials demonstrated that mupirocin significantly reduced the incidence of S aureus-associated SSIs.²³

Operative Characteristics

Wound classification (Table 3), a system developed by the National Academy of Sciences and the National Research Council, is a strong predicting factor for subsequent development of SSI.²⁴ Clean wounds are characterized by incision into nonviscus, uninfected, noninflamed tissue that is subsequently closed primarily. Clean-contaminated wounds result from intentional, controlled entry in a hollow viscus (respiratory, alimentary, genital, or urinary tract) without subsequent contamination. Contaminated wounds, on the other hand, involve accidental visceral entry, operations complicated by gross spillage, departure from sterile technique, or incision into an area of purulent inflammation. Dirty wounds involve surgery on tissue with retained devitalized tissue, foreign bodies, fecal contamination, perforated viscus, or existing, ongoing clinical infection. A near-linear relationship of escalating wound classification and subsequent SSI has been demonstrated in the literature, with as low as 1.3% of clean wounds and as many as 40% of dirty cases complicated by SSI.^25–28

In addition to wound classification, emergency procedures, long procedure length, the use of nonabsorbable suture, foreign bodies, copious use of subcutaneous electrocautery, excessive blood loss, and hypothermia have all been correlated with increased risk of SSI.^24,29

Patient Skin Preparation in the Operating Room

The purpose of preoperative skin antisepsis is to remove soil and transient organisms from the skin. The skin is a dynamic home to a large number of bacteria, with up to 3 million microorganisms on each square centimeter of skin.⁶⁴ Most commonly, SSI occurs from commensal organisms such as staphylococci, diphtheroid organisms, Pseudomonas, and propionibacterium species that are consistently present on a patient’s skin, compared with transient organisms that are more easily removed. Any chemical agent for microbial reduction of the skin ideally kills all skin organisms, is nontoxic and hypoallergenic, does not result in significant systemic resorption, has residual activity, and is safe for repetitive use.⁶⁵ Antiseptics are split into 3 major types: iodine/iodophor, chlorhexidine, and alcohol-based preparations (Table 4).²