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Reducing the Risk of Infection in the Elective and Emergent Colectomy Patient


Colorectal surgery is associated with a greater risk for infections than most other surgical specialties and is considered an outlier for surgical site infections (SSIs). In addition to SSI, as with other types of surgical operations, patients undergoing colectomy are at risk for respiratory, urinary tract, and line-related infections, as well as the development of Clostridium difficile . Perioperative measures can reduce the occurrence of these complications and improve outcomes.

Surgical Site Infection

Colorectal surgery continues to have one of the highest rates of SSI among surgical procedures, with reported rates between 5% and 30%. SSIs are the most frequent adverse event after colorectal surgery and comprise a spectrum of infections occurring at the surgical site, ranging from a mild superficial infection to deep-seated abdominal cavity infections on the other side of the spectrum. The US Centers for Disease Control and Prevention (CDC) has developed criteria that define SSI as infection related to an operative procedure that occurs at or near the surgical incision within 30 days of the procedure or within a year if prosthetic material is implanted at surgery. SSIs are divided anatomically into three categories of superficial, deep, and organ/space infections ( Table 179.1 ). Superficial infections involve the skin and subcutaneous tissues, deep infections involve the muscle and fascia, and organ/space infections arise in the abdominal cavity. The CDC diagnostic criteria of SSIs have become the accepted national standard and are followed by medical staff, hospitals, health care organizations, and surveillance and quality control programs.

TABLE 179.1
Classification and Definition of a Surgical Site Infection
Modified from Mangram AJ, Horan TC, Pearson ML, Silver LC, Jarvis WR. Guideline for prevention of surgical site infection. Infect Control Hosp Epidemiol. 1999;20:247–280.
SUPERFICIAL INCISIONAL SSI
Infection occurs within 30 days after the operation, and infection involves only skin or subcutaneous tissue of the incision and at least ONE of the following:

  • 1

    Purulent drainage, with or without laboratory confirmation, from the superficial incision.

  • 2

    Organisms isolated from an aseptically obtained culture of fluid or tissue from the superficial incision.

  • 3

    At least one of the following signs or symptoms of infection: pain or tenderness, localized swelling, redness, or heat AND superficial incision is deliberately opened by surgeon, UNLESS incision is culture negative.

  • 4

    Diagnosis of superficial incisional SSI by the surgeon or attending physician.

DEEP INCISIONAL SSI
Infection occurs within 30 days after the operation if no implant is left in place or within 1 year if implant is in place and the infection appears to be related to the operation, and infection involves deep soft tissues (e.g., fascial and muscle layers) of the incision and at least ONE of the following:

  • 1

    Purulent drainage from the deep incision but not from the organ/space component of the surgical site.

  • 2

    A deep incision spontaneously dehisces or is deliberately opened by a surgeon when the patient has at least one of the following signs or symptoms: fever (>38°C), localized pain, or tenderness, unless site is culture negative.

  • 3

    An abscess or other evidence of infection involving the deep incision is found on direct examination, during reoperation, or by histopathologic or radiologic examination.

  • 4

    Diagnosis of a deep incisional SSI by a surgeon or attending physician.

Notes

  • 1

    Report infection that involves both superficial and deep incision sites as deep incisional SSI.

  • 2

    Report an organ/space SSI that drains through the incision as a deep incisional SSI.

ORGAN/SPACE SSI
Infection occurs within 30 days after the operation if no implant is left in place or within 1 year if implant is in place and the infection appears to be related to the operation, and the infection involves any part of the anatomy (e.g., organs or spaces), other than the incision, which was opened or manipulated during an operation and at least one of the following:

  • 1

    Purulent drainage from a drain that is placed through a stab wound into the organ/space. If the area around a stab wound becomes infected, it is not an SSI. It is considered a skin or soft tissue infection, depending on its depth into the organ/space.

  • 2

    Organisms isolated from an aseptically obtained culture of fluid or tissue in the organ/space.

  • 3

    An abscess or other evidence of infection involving the organ/space that is found on direct examination, during reoperation, or by histopathologic or radiologic examination.

  • 4

    Diagnosis of an organ/space SSI by a surgeon or attending physician.

SSI , Surgical site infection.

SSIs in colorectal surgery are associated with significant morbidity, mortality, and increased health care costs, frequently requiring prolonged hospitalization, readmission, or even reoperation during the course of treatment. A study analyzing the impact of SSIs on hospital use and treatment costs using the Healthcare Cost and Utilization Project National Inpatient Sample (HCUP NIS) database found that SSIs extend the length of stay by an average of 9.7 days, while increasing costs by $20,842 per admission. Because of the frequency and severity of their impact, many methods to prevent and reduce SSIs have been implemented. Preventing SSIs is a multidisciplinary endeavor; involving the entire health team, including nurses, surgical staff, and physicians, is critical. It may involve taking measures at every step of the care process, ranging from preoperative optimization, to the operating room and postoperative care, combined with audit and surveillance of SSI rates and providing feedback, as well as education to health care personnel when appropriate.

Pathogenesis and Microbiologyof Surgical Site Infections in Colorectal Surgery

SSIs in colorectal surgery originate in the majority of cases from contamination of the surgical site with the patient's endogenous flora, with the colonic lumen being the major (>80%) source of bacterial contamination. The colon is a repository of a large number of gram-negative and gram-positive, aerobic as well as anaerobic bacteria, with counts as high as 10 per gram of content, containing more than 600 different species of bacteria. The higher the number of contaminating bacteria at the surgical site (inoculum), the higher the probability of developing an SSI because the quantity of bacterial contamination may exceed the capacity of the host for clearance. Escherichia coli and Bacteroides fragilis are the most likely organisms to be encountered at the contaminated site, B. fragilis being the organism with the highest density in the left colon and rectosigmoid but inconsistently cultured because of its obligate anaerobic nature. Aerobic (E. coli) and anaerobic (B. fragilis) colonic species can have a synergistic relationship that enhances their virulence when both species are concurrently present at a critical inoculum at the surgical site. Klebsiella pneumoniae and Enterococcus species are common in the colon but infrequent causes of SSIs. Pseudonomas aeruginosa , Serratia species, and Acinetobacter species can be encountered in SSIs after colorectal surgery, especially in patients with prior antibiotic exposure or prolonged hospital stay resulting in alteration of the normal native microflora.

Skin colonization can be a source for a smaller percentage (<20%) of infections. SSIs may originate from exogenous sources brought within the sterile field, such as the operating room environment, infected instruments and materials, or members of the surgical team. Staphylococcus species (e.g., S. aureus including methicillin-resistant S. aureus and coagulase-negative staphylococci) are responsible for the majority of SSIs caused by skin or operating room environmental contaminants.

Another variable that may lead to SSIs after colorectal surgery is the patient's (host's) responsiveness to eradicating microbes. Innate or acquired immunodeficiency and chronic conditions, such as diabetes and liver, kidney, or lung insufficiency, as well as cancer, impair the host responsiveness and are associated with increased SSI rates in colorectal surgery.

Environmental and technical factors may contribute to SSIs in colorectal surgery, even with reduced bacterial counts; hematomas or necrotic tissue at the surgical site that provide a rich supply of nutrients, foreign bodies that cannot be cleaned by the host's phagocytes, and the presence of dead space that provides an aqueous environment for bacterial growth all enhance microbial replication and accordingly increase SSIs. In addition, stool spillage during colorectal resection may seed the peritoneal cavity with high amounts of microbial contaminants that cannot be eradicated by the innate host response, leading to accumulation of colonic contents in areas of dependent drainage in the abdominal cavity, such as the pelvis or the paracolic gutters, leading to an abscess.

Another important factor for development of SSIs, especially organ/space SSIs, following colorectal resection is the development of an anastomotic leak. Anastomotic leak rates between 2% and 20% have been reported after colorectal surgery, with rates being higher for rectal surgery. Patient factors such as age, sex, obesity, comorbidities, radiation and chemotherapy, as well as other determinants such as surgical technique and experience have all been shown to be important determining factors of anastomotic leak risk.

Preoperative Measures for Prevention of Surgical Site Infections in Colorectal Surgery

Malnutrition

Preoperative malnutrition is commonly observed in patients undergoing colorectal surgery, with reported rates as high as 30% to 50%. Preoperative malnutrition is a major risk factor for increased postoperative morbidity and mortality. Hypoalbuminemia, with levels below 3.5 g/dL, especially in colorectal cancer patients significantly contributes to postoperative morbidity. Although currently there is insufficient data to suggest that preoperative nutritional supplementation prevents SSIs, data from limited studies suggest that preoperative nutritional assessment and support may prove to be helpful in wound healing.

Active Infection

If active infection is already present in the surgical site, it is considered to be a dirty wound. A near-linear relationship of escalating wound classification and subsequent SSIs has been demonstrated in the literature, with SSI rates as high as 40% for dirty wounds. The presence of infection impairs the wound healing process because bacteria produce inflammatory mediators that inhibit the inflammatory phase of wound healing and prevent epithelialization. Therefore it is recommended to allow healing of an active wound at the surgical site, if possible, before proceeding with elective colorectal surgery.

Smoking Cessation and Nicotine Replacement Therapy

Cigarette smoking interferes with primary wound healing, possibly secondary to constriction of peripheral blood vessels, leading to tissue hypovolemia and hypoxia. Smoking has been associated with poor perineal wound healing and deep SSIs after colorectal surgery. In 2003 a randomized controlled trial demonstrated that abstinence from smoking for as little as 4 weeks significantly reduced SSIs. No difference between transdermal nicotine patch and placebo was found. Based on these findings, smoking cessation and nicotine replacement therapy should be strongly recommended before elective colorectal resection.

Prolonged Preoperative Hospitalization

Preoperative hospitalization of as little as 2 to 4 days has been associated with increased incidence of SSI rates and other hospital-acquired infections. It is likely that colonization with resistant skin or colonic flora may lead to the increased resistance to preventive antibiotics and thus high SSI rates. Prolonged hospitalization is also a surrogate for patient and case complexity, resulting in higher complication rates.

Preoperative Cleansing of the Surgical Site

Preoperative showering and scrubbing of the surgical site with antiseptic soap or antiseptics has been proposed as a means of reducing SSIs. It is unclear whether reducing skin microflora leads to a lower incidence of SSIs. In a meta-analysis including 10,157 participants, bathing with chlorhexidine compared with placebo did not result in a statistically significant reduction in SSIs. Given that the major source of SSIs after colorectal surgery is from the colon, it is unlikely that aggressive skin cleansing will have a major impact on SSIs. However, almost all enhanced recovery programs include preoperative and postoperative skin-cleansing protocols.

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