Surgical site infections (SSI) have a high incidence, accounting for 20% of all hospital-acquired in-fections. Surgical site infections are linked to a increased length of stay and the risk of mortality. Although most patients recover from an SSI, 77% of mortality can be attributed to the infection it-self 1, 4. The incidence of SSI is 2% to 5% undergoing inpatient surgery 1. Estimated annual in-cidence varies, but may range from 160,000 to 300,000 in the US 1, 4. These estimates might be understated, given the surveillance failure after discharge
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Copyright © 2019 Rodrigo A. S. Sardenberg, et al.
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Surgical site infections (SSI) have a high incidence, accounting for 20% of all hospital-acquired infections. Surgical site infections are linked to a increased length of stay and the risk of mortality. Although most patients recover from an SSI, 77% of mortality can be attributed to the infection itself 1, 4. The incidence of SSI is 2% to 5% undergoing inpatient surgery 1. Estimated annual incidence varies, but may range from 160,000 to 300,000 in the US 1, 4. These estimates might be understated, given the surveillance failure after discharge.
The development of a SSI increases costs in the clinical and surgery outcomes. Certain patients may also require reoperation with SSI, which is associated with additional costs 5. Broex et al. showed that in European hospitals patients who develop an SSI, the costs are double that of patients who do not 6. In the same review, length of hospitalization was more than twice as long for patients with an SSI 6. SSI may displace hospital resources that would be spent elsewhere, as well as delay patient´s operation.
SSI impacts on patient physical and mental health, morbidity and mortality. Moreover, patients may experience delayed wound healing and be more susceptible to other complications, such as sepsis 7, 8. Prolonged hospitalization and increased morbidity have been shown to negatively impact on patient health-related quality of life (HRQoL) 9.
Surgical Site Infections
Surgical site infections (SSIs) are defined as infections occurring up to 30 days after surgery, (or up to one year after surgery with implants) and may affect the incision and/or deep tissue at the operation site 10.
There are three different types of SSI defined by the Centers for Disease Control and Prevention (CDC): superficial infections, deep infections or involving organs or body spaces (Table 1) 11. SSI in deep incisions or organ spaces account for 50% of all SSI 12. The degree of contamination at the time of surgery influences the probability of SSI.Table 1. Surgical site infection classification
|Purulent drainage from the superficial incision, with organisms isolated from culture.|
|Pain, swelling, redness, or heat|
|Presence of abscess|
|Infection of an episiotomy or newborn|
|Purulent drainage from the deep incision|
|A deep incision dehisces|
|An abscess or infection involving deep incision found on direct examination or during reoperation|
|Purulent drainage from a drain that is placed through wound into the organ/spaceand organisms isolated from obtained from a culture|
|Abscess or infection involving the organ/space that is found on direct examination, reoperation, or radiologic examination.|
Before antibiotic prophylaxis the rates were about 1-2% for clean wounds, 6-9% for clean-contaminated wounds, 13-20% for contaminated wounds and 40% for dirty wounds 14, particularly with surgical procedures with high risk of infection (gastrointestinal) 15. Yet, SSI remain a important cause of morbidity and death, maybe because of elderly surgical patients or chronic and immunocompromising diseases, prosthetic implants and organ transplantation 16. We could observe little variation in the distribution of the pathogens isolated 17. However, the change in the microbiology of SSI has increased involvement of microorganisms resistant to antibiotics.
Surgical procedures involving ’clean’ cavities have less infection (3% to 5%), compared with procedures involving infected, necrotic or dirty tissues. Colorectal surgery, for example, might have surgical infection around 10% to 30% .
Deﬁnition of classiﬁcation of surgical procedures is described as follows on table 2:Table 2. Infection according to wound classification.
|Wound class||Definition||Example||Infection rate %|
|Clean||Non-traumatic, elective surgery, GI, respiratory and GU tract not entered||Mastectomy, vascular, hernias||2%|
|Clean-contaminated||Respiratory, GI,GU tract entered||Gastrectomy, hysterectomy||< 10%|
|Contaminated||Open, fresh, traumatic wounds, uncontrolled spillage, miner break in sterile Technique||Rupture app, emergent bowel resect||20%|
|Dirty||Open, traumatic, dirty wounds; traumatic perforation of hollow viscus, frank pus in the field||Intestinal fistula resection||28-70%|
References for this review were identified through searches of PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE (Ovid)CINAHL, and World Health Organization (WHO), for articles published from January 1990 to March 2018 by use of the terms “surgical site infection,” “ surgical procedures “ and “surgical infections”. We also looked for clinical trials, meta-analysis and systematic reviews.
There are a interventions consensus statements and guidelines that covers the pre-hospital setting and the post-discharge conditions. In the present study, we provide a brief of these guidelines.
Pre-operative bathing with chlorhexidine decreases skin pathogen concentrations, but do not reduce SSI 3.
Blood glucose control should be done for all diabetic patients, but there is no evidence that decreases SSI risk 6.
MRSA Screening Intervention
Clinical practice guidelines from the American Society of Health-System Pharmacists recommend screening decolonization for S aureus-colonized patients before joint replacement and cardiac procedures 20.
There is no standard decolonization protocol supported by literature, although should be completed close to date of surgery to be effective.
Mechanical cleaning and antibiotic prophylaxis is recommended for elective colectomies.
A significant number of SSIs occur following various surgical specialties in the world. Recent analysis of European studies confirmed that the financial burden of surgery is consistently higher in patients who develop an SSI, relative to uninfected patients. The mean total cost of orthopedic and trauma surgery in those who developed an SSI was about 2.9 times higher than the costs associated with patients who did not.
The literature generally supports the administration of prophylactic antibiotics within 1 hour before incision, or within 2 hours for vancomycin or fluoroquinolones, when indicated according to the type of operation. Administration before 120 minutes or after incision is associated with a higher risk of surgical site infection. The exact optimal timing within this timeframe cannot be defined according to the available evidence but half-life and protein- binding of the antibiotic should be taken in to account, also according to the underlying conditions of the individual patient. However, the evidence comes from studies with limited methodological quality and definitive randomized controlled trials are still needed. Prophylactic antibiotics should be redosed during surgery to maintain adequate tissue levels based on the agent’s half- life or for every 1,500 mL estimated blood loss.
Providers should be aware of the common pathogens responsible for SSI (S aureus, coagulase ne-gative staphylococci, Enterococcus species, and Escherichia coli), as well as the patterns of resistance at their institutions 20. Whenever possible, providers should use hospital- specific antibiograms and diverse antibiotic agents to decrease resistance among pathogens. As discussed previously, in elective colorectal procedures, a combination of oral antibiotic bowel preparation and IV prophylactic antibiotics should be used. Vancomycin should not be administered routinely as prophylaxis in MRSA- negative patients 21. Antibiotics should be discontinued at time of incision closure (exceptions include implant-based breast reconstruction, joint arthroplasty, and cardiac procedures for which optimal duration of antibiotic therapy remains unknown). In general, there is no evidence that antibiotic administration after incision closure decreases SSI risk across a range of procedures, including clean, clean-contaminated, and contaminated wound classes 20, 21. Antibiotic prophylaxis after cardiothoracic procedures to continue until 48 hours postoperatively, however, many studies have shown no increased SSI risk with earlier antibiotic termination by 24 hours 20.
Future research should well describe and standardize aspects affecting the effect of timing. Also different pharmacokinetic properties should be taken in account. A protocol for a randomized control trial has been published earlier in 2015 17.
Skin antiseptic preparation is aimed at reducing bacterial colonization of the skin and the risk of wound contamination during the surgical procedure. Iodophor (such as povidone-iodine (PI)) and chlorhexidine gluconate (CHG) are the main types of antiseptics and can be mixed with either alcohol or water. Chlorhexidine reduces skin bacterial colony counts to a greater extent than PI does or other agents that have been studied 18. Adjunctive means to reduce contamination include measures to reduce airborne contamination in the operating room by use of tight scrub-suits and laminar airflow. The use of plastic adhesive drapes on the skin is commonly practiced but should be questioned, as it has in fact not been shown to reduce SSIs and might even increase the re- colonization of the skin 19.
Studies have shown that intra-operative hypothermia is associated with increased risk of SSI, therefore, intraoperative maintenance of normothermia is recommended. The use of preoperative warming before short, clean cases has been shown to reduce SSI and is recommended. For longer cases, both preoperative warming and ongoing temperature monitoring and warming measures are recommended 22.
Literature supports the use of wound protectors in reducing SSI, although data are mixed. Many prospective, randomized trials have demonstrated substantial reductions in SSI rate with the use of plastic wound edge protectors, although many of these studies are limited by small sample sizes.Some of these studies demonstrated considerable benefit in a more defined patient population, such as patients undergoing elective colorectal surgery 23. The use of an impervious plastic wound protector can prevent SSI in open abdominal surgery, and evidence is strongest for elective colo- rectal and biliary tract procedures. The optimal postoperative wound management practices remain undefined, including how best to survey for SSIs after discharge from the hospital.
Traditional teaching has supported primary closure for clean and clean-contaminated cases, but delayed primary closure (DPC) or open wound management for contaminated and dirty wounds, given the increased risk of SSI. Recent research has questioned this dogma and explored whether primary closure can be acceptable for all wound classes 24. Overall, there are no good quality data to support primary closure vs DPC in contaminated and dirty abdominal incisions, although systematic reviews suggest there might be decreased SSI with DPC. A prospective trial comparing primary closure with DPC reported that 48% of patients with primary closure were discharged with open wounds compared with 58% of patients with DPC (p 1⁄4 NS). In the setting of damage-control laparotomy, primary closure was associated with a higher rate of intra-abdominal infection, however, SSI did not develop in >85% of patients closed primarily 25. Table 3 shows SSI at wound closure of an infected wound.Table 3. Incidence of SSI of infected wounds
|Opening and re-closure times||Re-infection rate %|
|Opening and re-closure at once||50|
|Opening and re-closure after 2 days||20|
|Opening and re-closure after 4 days||5|
|Opening and re-closure after 9 days||10|
The aim of wound irrigation and lavage is to reduce the bacterial load in a surgical or traumatic wound by a combination of water pressure, dilution, or the application of antimicrobial agents. Usually, this is undertaken at the end of an operative procedure, prior to wound closure, to reduce the likelihood of the introduction of bacteria. Both wound irrigation and intra-cavity lavage can be achieved using various solutions. Normal saline is commonly used along with antimicrobial agents for intra-cavity lavage. However, there is concern that antimicrobial agents may damage tissue and prevent nor- mal healing. It is thought that the introduction of large volumes of fluid into a cavity or wound could wash away inflammatory cells vital to the host defence 26.
The use of topical and local antibiotic therapy options for SSI reduction has been explored in many surgical subspecialties, but there is a lack of high-quality data to support those therapies use to decrease SSI. It includes: antibiotic irrigations, topical antimicrobial agents, antimicrobial-impregnated dressings, and wound sealants 27. There is some support in the literature for topical or local antibiotic use for specific procedures or patient populations. A recent systematic review found possible benefit for use in joint arthroplasty, cataract surgery, and possibly in breast augmentation and obese patients undergoing abdominal surgery 28. There is weak evidence in the literature to support routine use of topical or local antimicrobial agents, although there might be benefit for specific procedures and patient populations. The evidence base for intra-cavity lavage and wound irrigation is generally of low certainty. Therefore, might have possible difference in the incidence of SSI (in comparisons of antibacterial and non-antibacterial interventions, and pulsatile versus standard methods) these should be considered in the context of uncertainty, particularly given the possibility of publication bias for the comparison of antibacterial and non-antibacterial interventions. Clinicians should also consider whether the evidence is relevant to the surgical populations under consideration, the varying reporting of other prophylactic antibiotics, and concerns about antibiotic resistance.
Peri-operative oxygen administration is a simple, low cost SSI prevention strategy. A meta-analysis concluded that peri-operative supplemental oxygen led to a relative risk reduction of 25% 30, 31. Through a standardized protocol, provide guidance on the appropriate and timely use of supplemental oxygen through the surgical peri-operative period for all patients.
SSI prevention is multifaceted and attainable by following evilence-based strategies and recommended guidelines. This effort requires a mustidisciplinary approach that includes surgeons, anesthesiologists, leaders, preoperative staff, infection preventionists, pharmacists, engineering and environmental services.
Furthermore, SSIs negatively impact on patient outcomes, increasing patient morbidity, mortality, and HRQoL. As the demand for surgical procedures rises, the incidence and associated costs of SSIs will likely escalate.
Ongoing monitoring of compliance to bundles for data-driven decision- making, using data to drive practice and process changes, and communication of supporting process performance and SSI rates to physicians and peri-operative staff, and are also key to success.