Surgical Site Infections

Key points

Definitions

To assist with appropriate surveillance of SSIs, establishing clear definitions for cases of SSIs was critical. The Centers for Disease Control and Prevention (CDC) established the National Healthcare Safety Network (NHSN) to monitor quality control measures, including SSIs, and has defined widely used definitions for SSI (Box 1).⁴ SSI are classified based on the depth of involvement of the infection, which may be confined to the skin and subcutaneous tissues (superficial incisional SSI),

Epidemiology

Recognizing the historical context of surgical infection can highlight the gains that have been made over the past few centuries. Before the antisepsis era, the risk of surgery was exceedingly high due to the enormous rates of surgical infection. Compounded by the absence of the effective anesthesia, early surgical procedures had limited success compared with the modern era. Acknowledgment of the aseptic approach made a significant impact on outcomes. The simple introduction of hand washing by

Risk factors for surgical site infection

From a general perspective, the microbes responsible for infection of surgical wounds originate from either the surrounding skin or associated structures that are contiguous with the regions of the surgical procedure. The logical extension of this principle is that the risk of wound contamination and subsequent SSI depends on location, the nature of the surgical wound/incision, and the procedure performed. The CDC wound classification system defines wound class based on risk and is divided into

Microbial factors

The predominant source of microbes involved in SSIs originate from either the skin or the surrounding tissues of the incision, or from deeper structures involved in the operative procedure (eg, enteric organisms in bowel-related surgeries). In the most recent NHSN surveillance report on 21,100 isolates from 2009 to 2010, the most frequently identified pathogens were, in order, Staphylococcus aureus, Coagulase-negative Staphylococci, Escherichia coli, Enterococcus faecalis, and Pseudomonas

Patient factors

Patient comorbidities can contribute significantly to the potential risk of SSIs. These factors include age, obesity, smoking, diabetes mellitus, malnutrition, dyslipidemia, and immunosuppression (see Box 2).⁴¹ These factors are not directly accounted for in the NNIS classification scheme but can contribute significantly to the risk of SSI. Identification of these risk factors with appropriate preoperative history and physical examination is critical. The core principle for management of these

Perioperative factors

Preventative measures in the preoperative period have changed rapidly over the past few decades. A large volume of research has established the importance of a host of preventative measures in the operative period. Examples include skin decontamination, perioperative warming, and antimicrobial prophylaxis.41, 44, 45 As additional studies have been conducted with increasing methodological rigor, from observational studies to randomized controlled trials, refinements of existing preventative

Major limitations in prevention

In an ideal scenario, primary prevention is completely effective and the burden of SSI-related morbidity is reduced to 0%. As described in later discussion, the relationship between compliance with evidence-based guidelines and SSI outcomes is imperfect. With the risk inherent with nonmodifiable risk factors, there will likely be a minimum prevalence that cannot be entirely eliminated. In addition, with the development of numerous evidence-based guidelines, there continue to be hurdles with

Therapy

The general principle of SSI therapy remains control of the source of infection. For superficial SSI, the standard management remains the use of incision and drainage.62, 95 The wound should be sufficiently sized to promote adequate drainage. A variety of local wound care options are available, with the simplest being saline-soaked cotton gauze dressings.⁶² For uncomplicated superficial SSIs, simple incision and drainage, with local wound care, are appropriate, with no antibiotic therapy

The economic and quality of care impact of surgical site infections

The economic costs of SSIs are significant because of the volumes of cases that are seen, with an annual 2.7 million operative procedures performed in the United States.⁵ Even with a conservative estimate of more than 290,000 cases of SSI,⁷ there is a substantial economic cost to the management of SSI. There is a wide variance in estimates of the attributable costs of SSI infection that depends heavily on the type of surgical procedure and the geographic region studied.⁹⁸ There is additional

Summary

SSIs remain a very important component of patient outcome, contributing to substantial patient morbidity. From a historical perspective, there has been a significant improvement in postsurgical outcomes, but these incremental gains have slowed in the recent decades. The translation of basic and clinical research has expanded the complexity of evidence-based guidelines for SSI prevention. The importance of SSI prevention has been heightened because of its association with institutional and