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Surgical Site Infection: What Causes the Infection?

September 29, 2021

Although advances in surgical techniques and operating room technologies have made many surgical procedures more successful and have led to easier recovery for many patients, surgical site infections (SSIs) remain a clinical problem. These infections are associated with increased morbidity, mortality, and health care costs.1

Epidemiology and Risk Factors

Although low- and middle-income countries have a global SSI incidence rate of 5.6%, SSI rates are still 2.6% in the United States, thus demonstrating that much work remains to be done because many of these infections are preventable.1 These infections are the most common and costly of all hospital-acquired infections and can be associated with an increased length of stay and a 2- to 11-fold increase in the risk of mortality.2

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Many patients recover from an SSI without adverse effects, but up to 77% of deaths in patients with an SSI can be attributed to the infection itself.2 Risk factors commonly associated with SSIs are a preoperative hospital stay of more than 24 hours, a long duration of surgery, and a wound that is clean-contaminated, contaminated, or dirty or infected.3

Prevention of Surgical Site Infections

Practices to prevent SSIs are primarily aimed at minimizing the number of microorganisms introduced into the operative site. Strategies include removing microorganisms that normally colonize the skin, preventing the multiplication of microorganisms at the operative site, and preventing access of microorganisms postoperatively by using wound dressings. Removing bacteria and reducing the number of commensal organisms with an antiseptic are recommended before surgery by several organizations, such as the Centers for Disease Control and Prevention. Antiseptic use can reduce the number of microorganisms within the surgical field.4

Wound infections, including SSIs, are often related to the microbial load of the infected wound. Once bacteria are inside the body, defense cells recognize the bacteria as foreign, thus triggering an immune system response marked by continuous inflammation. Prolonged inflammation may stall the healing process and prevent the wound from closing.5

Because of the threat of bacteria in causing or contributing to the development of an SSI, best practices focus on reducing the burden of infectious organisms from the skin’s microbiome6 and guarding against introducing these organisms during operative and postoperative care. These strategies include the following2:

  • Preoperative bathing and showering with chlorhexidine to reduce bacterial colonization.
  • Smoking cessation: Smoking is associated with an increased risk for an SSI related to poor tissue perfusion and vasoconstriction of vessels in the surgical bed that can lead to tissue hypovolemia and hypoxia. Regardless of the type of surgery, smokers are at higher risk for an SSI. It is recommended that patients quit at least four to six weeks before elective surgery.
  • Glucose control: Perioperative hyperglycemia increase the risk of SSI in both diabetic and non-diabetic patients. Short-term glucose control can make an impact on decreasing the risk of an SSI.
  • Surgical hand scrubbing: Poor-quality surgical hand scrubbing can contribute to intraoperative risk factors. Waterless chlorhexidine scrub is as effective as traditional water-based scrubs and requires less time.
  • Intraoperative hypothermia is associated with an increased risk of SSI. Preoperative warming, ongoing monitoring, and warming measures are recommended.
  • Postoperative wound management may include the use of negative pressure wound therapy, various dressing materials, and the timing of dressing changes. Silver dressings can help reduce SSI risk in some wounds. Managing the wound and maintaining a clean wound are crucial in decreasing the risk of SSIs.


These guidelines provide a starting point for delivering evidence-based care and preventing many SSIs, thereby leading to better patient outcomes and reduced health care costs.

1. Tartari E, Weterings V, Gastmeier P, et al. Patient engagement with surgical site infection prevention: an expert panel perspective. Antimicrob Resist Infect Control. 2017;6:45.
2. Ban KA, Minei JP, Laronga C, et al. American College of Surgeons and Surgical Infection Society: surgical site infection guidelines, 2016 update. J Am Coll Surg. 2016;224(1):59-74.
3. Carvalho RLR, Campos CC, Franco LMC, Rocha AM, Ercole FF. Incidence and risk factors for surgical site infection in general surgeries. Rev Lat Am Enfermagem. 2017;25:e2848.
4. Privitera GP, Costa AL, Brusaferro S, et al. Skin antisepsis with chlorhexidine versus iodine for the prevention of surgical site infection: a systematic review and meta-analysis. Am J Infect Control. 2017;45(2):180-189.
5. Komski L. The impact of endotoxin on the human body. Fujifilm Wako Chemicals U.S.A.; 2014. Accessed August 22, 2021.…
6. Wenzel RP. Surgical site infections and the microbiome: an updated perspective. Infect Control Hosp Epidemiol. 2019;40:590-596.

The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, HMP Global, its affiliates, or subsidiary companies.

The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, HMP Global, its affiliates, or subsidiary companies.