Surgical Site Infections - Preventable or Predictable

2011 - 6 December - Infection in the ICU
Sean A. Nix, DO; Roxie M. Albrecht, MD
Understand the types of surgical site infections, risk factors and preventive measures.
 
For centuries surgeons believed in the benefits of laudable purulence after a surgery. Famous names such as Koch, Semmelweis and Lister started a revolution in surgery with the development of the aseptic technique in the 1800s. Since then, surgical infections have been reduced greatly and surgery is a much safer prospect for our patients. The Centers for Disease Control and Prevention (CDC) defines surgical site infections (SSIs) as infections that occur at surgical sites within 30 days – or within one year for procedures involving implants.(1)
 
There are three major categories of SSIs: superficial incisional, deep incisional and organ/space.(1) An estimated 27 million surgical procedures are conducted each year in the United States; based on a national database SSIs occur at a rate of two per 100 procedures.(2) De Lissovoy et al found an overall rate of 9.5 per 1000 surgical hospitalizations.(3) In addition to increasing length of stay (LOS) by 9.7 days, treating SSIs can cost between $400 to more than $30,000.(2,4,5) Broex et al cited difficulties in determining the actual cost due to study differences and currencies, but found a 115% mean increase in cost and 176% increase in LOS.(6) German workers reported that SSIs increased cost by $3,859 to $40,559.(5) The cost of a coronary artery bypass graft surgery (CABG) nearly triples when an SSI occurs.(7) The exact costs are difficult to estimate, but they are a significant burden.
 
SSIs account for 20% of healthcare-associated infections.(2) Weigelt et al reported a total mortality rate of 0.95% for SSIs.(8) Mortality rates for specific procedures can double when a patient develops an SSI.(9-12) Patients who undergo CABG may have a one-year mortality rate of 20% if they develop a deep chest surgical site infection, compared to 0.6% for patients without an infection. Elderly populations almost triple their odds of death from SSI when compared to younger patients.(12) Orthopedic patients who develop SSI have been found to be 4.5 times less likely to survive.(8)
 
Patients acquire the organisms predominantly from skin flora or other endogenous sources. A few cases of SSI have been reported from exogenous sources in the operating room or healthcare workers.(13) As expected, Staphylococcus species accounted for nearly 50% of infections, with methicillin-resistant Staphylococcus aureus (MRSA) accounting for 13.7%.(1,8) The next highest group was caused by polymicrobial infections and small percentages of other organisms.(1,8) Resistant organisms associated with SSIs are an increasing problem. In one study conducted between 2000 and 2007, the rate of MRSA infections doubled; in another, the total number increased from 16% to 20% of SSIs.(8,14) MRSA significantly increases the mortality rate of SSIs.(8,14,15) There are multiple risk factors for developing SSIs (see Table 1),(1) including hypoxia, hypothermia and blood product transfusions.(16,17) Wounds with elevated amounts of initial contamination have higher SSI rates (see Table 2).(18,19) De Lissovoy et al used national databases to establish rates and found obstetrics and gynecology had the lowest rate with an odds ratio (OR) of 0.06%. The risk of developing an SSI varied according to type of surgery, with reported ORs of 3.85 for neurologic, 12.00 for cardiovascular, 45.24 for colorectal, and 2.90 for dermatologic.(3) The risk for developing SSI is a complex interaction between the patient, the procedure and environmental factors.
 
Interventions are aimed at modifying patient factors and environmental factors. As reviewed by Kirby and Mazuski, class I evidence is scarce; it is mostly class II.(13) Well-documented interventions include blood glucose levels below 200 mg/dL, improving nutritional status in malnourished individuals, and smoking cessation.(16) Other prevention techniques – such as clipping hair versus shaving, administering first- or second-generation cephalosporin within one hour of the procedure’s start, minimizing surgical drains and repeating antibiotic doses – also are supported by data.(16) There are national efforts, such as the CDC Surgical Care Improvement Project (SCIP) and the American College of Surgery – National Surgical Quality Improvement Project (ACS-NSQIP), to decrease surgical infections and improve outcomes. As shown in Table 2, the ACSNSQIP data reveal a lower rate of infections in the highly contaminated wounds. Whether this is the result of these interventions is not yet determined by the data. Treatment of SSIs is aimed at source control of the infection. Skin and subcutaneous infections may be drained directly and cultures obtained. Deep or organ space infections may require imaging-directed percutaneous drain placements or procedures. Drainage of the infection is considered paramount and antibiotics are secondary.(13) Many superficial infections do not necessarily require antibiotic therapy if adequately drained. Patients with deep infections or with those that present with clinical signs of systemic inflammatory response syndrome or sepsis will require empiric antibiotic therapy to cover suspected organisms depending on the source.
 
The CDC SCIP and the ACS-NSQIP were developed to reduce SSIs and make surgery safer. Larochelle et al recently reported that SCIP does little to reduce SSIs.(20) Some workers have published decreased SSIs with SCIP and others have not seen a difference.(20-22) Previous review of NSQIP data has shown mixed results on reducing SSIs, but the most recent data seem to indicate a reduction in certain wound categories (Table 2).(19,25) Both programs have been shown to reduce mortality.(23,24) Eliminating SSIs may be impossible due to the interaction of patient, environmental and unalterable risk factors. The goal of these programs should be to make surgery as safe a prospect as possible by including the entire patient care team in the prevention of adverse outcomes. A large study in Europe utilized an extensive, multi-page surgical checklist at every stage of the patients’ progress through their surgery.(26) The overall complication and mortality rates were lower, but no change in SSIs was noted. The study illustrated that even with meticulous safeguards and a decrease in overall adverse events, there remains an intrinsic infection rate that may be minimized, but not eradicated.
 
References

1. Mangram AJ, et al. Guideline for prevention of surgical site infection, 1999. Centers for Disease Control and Prevention (CDC) Hospital Infection Control Practices Advisory Committee. Am J Infect Control. 1999; 27: 7-132; quiz 133-134; discussion 96.
2. Klevens RM, et al. Estimating health care-associated infections and deaths in U.S. hospitals, 2002. Public Health Rep. 2007; 122:160-166.
3. de Lissovoy G, et al. Surgical site infection: incidence and impact on hospital utilization and treatment costs. Am J Infect Control. 2009; 37:387-397.
4. Urban JA. Cost analysis of surgical site infections. Surg Infect (Larchmt). 2006; 7 Suppl 1: S19-S22.
5. Fry DE. The economic costs of surgical site infection. Surg Infect (Larchmt). 2002; 3 Suppl 1: S37-S43.
6. Broex EC. et al. Surgical site infections: how high are the costs? J Hosp Infect. 2009; 72:193-201.
7. Graf K, et al. Surgical site infections--economic consequences for the health care system. Langenbecks Arch Surg. 2011; 396:453-459.
8. Weigelt JA, et al. Surgical site infections: Causative pathogens and associated outcomes. Am J Infect Control. 2010; 38: 112-120.
9. Hollenbeak CS, et al. The clinical and economic impact of deep chest surgical site infections following coronary artery bypass graft surgery. Chest. 2000; 118:397-402.
10. Kirkland KB, et al. The impact of surgical-site infections in the 1990s: attributable mortality, excess length of hospitalization, and extra costs. Infect Control Hosp Epidemiol. 1999; 20:725-730.
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12. Pollard TC, et al. Deep wound infection after proximal femoral fracture: consequences and costs. J Hosp Infect. 2006; 63:133-139.
13. Kirby JP, Mazuski JE.  Prevention of surgical site infection. Surg Clin North Am. 2009; 89:365-389, viii.
14. Anderson DJ, et al. Severe surgical site infection in community hospitals: epidemiology, key procedures, and the changing prevalence of methicillin-resistant Staphylococcus aureus. Infect Control Hosp Epidemiol. 2007; 28: 1047-1053.
15. Dohmen PM. Influence of skin flora and preventive measures on surgical site infection during cardiac surgery. Surg Infect (Larchmt). 2006; 7 Suppl 1:S13-S17.
16. Anderson DJ. Surgical site infections. Infect Dis Clin North Am. 2011; 25: 135-153.
17. Edmiston CE, et al. Reducing the risk of surgical site infections: did we really think SCIP was going to lead us to the promised land? Surg Infect (Larchmt). 2011; 12:169-177.
18. Culver DH, et al. Surgical wound infection rates by wound class, operative procedure, and patient risk index. National Nosocomial Infections Surveillance System. Am J Med. 1991; 91(3B):152S-157S.
19. Ortega G. et al. An evaluation of surgical site infections by wound classification system using the ACS-NSQIP. J Surg Res. 2011 Jun 24 [Epub ahead of print]
20. Larochelle M. et al. Diminishing surgical site infections after colorectal surgery with surgical care improvement project: is it time to move on? Dis Colon Rectum. 2011; 54:394-400.
21. Pastor C, et al. An increase in compliance with the Surgical Care Improvement Project measures does not prevent surgical site infection in colorectal surgery. Dis Colon Rectum. 2010; 53:24-30.
22. Stulberg JJ, et al. Adherence to surgical care improvement project measures and the association with postoperative infections. JAMA. 2010; 303:2479-2485.
23. Hall BL, et al. Does surgical quality improve in the American College of Surgeons National Surgical Quality Improvement Program: an evaluation of all participating hospitals. Ann Surg. 2009; 250:363-376.
24. Khuri SF, et al. The Department of Veterans Affairs' NSQIP: the first national, validated, outcome-based, risk-adjusted, and peer-controlled program for the measurement and enhancement of the quality of surgical care. National VA Surgical Quality Improvement Program. Ann Surg. 1998; 228: 491-507.
25. Ingraham AM, et al. Association of surgical care improvement project infection-related process measure compliance with risk-adjusted outcomes: implications for quality measurement. J Am Coll Surg. 2010; 211:705-714.
26. de Vries EN, et al. Effect of a comprehensive surgical safety system on patient outcomes. N Engl J Med. 2010; 363:1928-1937.
 
 Disclosures
 
The authors have no disclosures to report.