Wound Infection Treatment & Management

Most patients with wound infections are managed in the community. Management usually takes the form of dressing changes to optimize healing, which usually is by secondary intention.

Resultant increased hospital stay due to surgical-site infection (SSI) has been estimated at 7-10 days, increasing hospitalization costs by 20%. ^{[18, 19, 20]} Occasionally, further intervention in the form of wound debridement and subsequent packing and frequent dressing is necessary to allow healing by secondary intention.

Guidelines for the management of SSI were published in 2014 by the Infectious Diseases Society of America ^[21] (IDSA), in 2017 by the Centers for Disease Control and Prevention ^[22] (CDC), in 2018 by the World Health Organization ^[23]  (WHO), and in 2019 by the Asia Pacific Society of Infection Control ^[24] (APSIC). (See Guidelines.)

The use of antibiotics was a milestone in the effort to prevent wound infection. The concept of prophylactic antibiotics was established in the 1960s when experimental data established that antibiotics had to be in the circulatory system at a high enough dose at the time of incision to be effective. ^{[25, 26]}

It is generally agreed that prophylactic antibiotics are indicated for clean-contaminated and contaminated wounds (see Table 2 in Overview). Antibiotics for dirty wounds are part of the treatment because infection is established already. Clean procedures might be an issue of debate. No doubt exists regarding the use of prophylactic antibiotics in clean procedures in which prosthetic devices are inserted; infection in these cases would be disastrous for the patient. However, other clean procedures (eg, breast surgery) may be a matter of contention. ^{[27, 28]}

Criteria for the use of systemic preventive antibiotics in surgical procedures are as follows:

• Systemic preventive antibiotics should be used in the following cases: A high risk of infection is associated with the procedure (eg, colon resection); consequences of infection are unusually severe (eg, total joint replacement); the patient has a high NNIS risk index
• The antibiotic should be administered preoperatively but as close to the time of the incision as is clinically practical; antibiotics should be administered before induction of anesthesia in most situations
• The antibiotic selected should have activity against the pathogens likely to be encountered in the procedure
• Postoperative administration of preventive systemic antibiotics beyond 24 hours has not been demonstrated to reduce the risk of SSIs

Qualities of prophylactic antibiotics include efficacy against predicted bacterial microorganisms most likely to cause infection (see Table 3 below), good tissue penetration to reach wound involved, cost effectiveness, and minimal disturbance to intrinsic body flora (eg, gut). ^[29]

Table 3. Recommendations for Prophylactic Antibiotics as Indicated by Probable Infective Microorganism Involved ^{[8, 30]} (Open Table in a new window)

The timing of administration is critically important because the concentration of the antibiotic should be at therapeutic levels at the time of incision, during the surgical procedure, and, ideally, for a few hours postoperatively. ^[8] Antibiotics are administered intravenously, generally 30 minutes prior to incision ^[30] ; they should not be administered more than 2 hours prior to surgery.

Colorectal surgical prophylaxis additionally requires bowel clearance with enemas and oral nonabsorbable antimicrobial agents 1 hour before surgery. ^[18] High-risk cesarean surgical cases require antibiotic administration as soon as the clamping of the umbilical cord is completed. ^[8]

The current risk index used to predict the risk of developing a wound infection is the NNIS system of the CDC. ^[8] The risk index category is established by the added total of the risk factors present at the time of surgery. For each risk factor present, a point is allocated; risk index values range from 0-3. This risk index is a better predictor for SSIs (see Table 4 below) than the surgical wound classification is (see Table 2 in Overview). ^[31]

Table 4. Predictive Percentage of SSI Occurrence by Wound Type and Risk Index* ^[31] (Open Table in a new window)

The NNIS risk index integrates the three main determinants of infection—namely, bacteria, local environment, and systemic host defenses (patient health status). The risk index does not include other risk variables, like smoking, tissue oxygen tension, glucose control, shock, and maintenance of normothermia. All these factors are relevant for clinicians but difficult to monitor and fit into a manageable risk assessment.

The elements constituting this index are as follows:

• Preoperative patient physical status assessed by the anesthesiologist and classified by the American Society of Anesthesiologists (see Table 5 below) as greater than 3
• Operation status as either contaminated or dirty-infected (see Table 2 in Overview)
• Operation lasting longer than T hours, where T is the 75th percentile of the specific operation performed

Table 5. American Society of Anesthesiologists (ASA) Classification of Physical Status ^[32] (Open Table in a new window)

Perioperative recommendations have been made for minimizing wound infection and SSI, supported by varying degrees of evidence (see Table 6 below).

Table 6. Data Support Recommendations (Open Table in a new window)

Preoperative patient preparation

Category IA recommendations for preoperative patient preparation include the following:

• Identify and treat all infections remote from the surgical site; delay operation in elective cases until infection is treated
• Do not remove hair unless it infringes on the surgical field; if hair removal is required, it should be removed immediately before operation and preferably with electric clippers

Category IB recommendations include the following:

• Patients should cease tobacco consumption in any form for at least 1 month preoperatively
• Optimize blood glucose level and avoid hyperglycemia
• Patients are to shower/bathe with antiseptic on at least the night before surgery
• Necessary blood products may be administered

The category II recommendation is as follows: Provided that preoperative patient preparation is adequate, minimize preoperative hospital stay.

No recommendations are made regarding the following:

• Gradual reduction/discontinuance of steroid use before elective surgery
• Enhanced nutritional intake solely to prevent SSI
• Preoperative topical antibiotic use in nares to prevent SSI
• Measures to enhance wound space oxygenation

Preoperative considerations for surgical team members

Category IB recommendations regarding preoperative considerations for surgical team members are as follows:

• Keep fingernails short; do not wear artificial nails
• Scrub hands and forearms as high as the elbows for at least 2-5 minutes with appropriate antiseptic
• After scrub, keep hands up with elbows flexed and away from the body; use a sterile towel to dry the hands and put on a sterile gown and gloves
• Masks should be worn in the operating suite if sterile instruments are exposed and throughout the surgical procedure; masks should cover the mouth and nose
• The hair on the head and face is to be covered with a hood or cap
• Liquid-resistant sterile surgical gowns and sterile gloves are to be worn by scrubbed surgical team members
• Visibly soiled gowns are to be changed
• Shoe covers are not necessary
• Routine exclusion of personnel colonized by organisms, such as S aureus or group A streptococci, is not necessary unless they are specifically linked to dissemination of such organisms
• Personnel with skin lesions that are draining are to be excluded from duty until treated and the infection has resolved
• Educate and encourage surgical personnel regarding reporting illness of transmissible nature to supervisory and occupational health personnel
• Policies should be established concerning patient care responsibilities for personnel with potentially transmissible infective illnesses, to include aspects of work restrictions, personnel responsibility in utilizing health services, and declaring illness; policies also should direct the responsible person to remove personnel from duty, and policy should be established for clearance to resume work

Category II recommendations are as follows:

• Clean under the fingernails prior to the first scrub of the day
• Do not wear arm/hand jewelry

No recommendations are made regarding the following:

• Nail polish
• Restriction of scrub suits to the operating theater
• Covering the scrub suits when outside the theater
• How or where to launder theater suites

Preoperative and postoperative wound care

A category IA recommendation for preoperative and postoperative wound care is that asepsis is necessary in the insertion of indwelling catheters, such as intravascular, spinal, or epidural catheters, and subsequent infusion of drugs. (See the image below.)

Abscess secondary to a subclavian line.

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Category IB recommendations include the following:

• Handle tissues gently with good hemostasis, minimize foreign bodies, and minimize devitalized tissue and dead space
• For class III and IV wounds, use delayed closure or leave the wound incision open to heal by secondary intention
• If draining of a wound is necessary, the drain exit should be via separate incision distant from the wound; remove the drain as soon as possible
• Primary closed incisions should be protected with a sterile dressing for 24-48 hours
• Hands are to be washed before and after wound dressing changes/or contact

Category II recommendations include the following:

• Use sterile technique for wound dressing change
• Educate the patient and relatives regarding wound care symptoms of SSIs and the need to report such problems

Theater environment and care of instrumentation

Category IB recommendations for the theater environment and the care of instrumentation include the following:

• Maintain positive-pressure ventilation of the operating suite relative to corridors and surrounding areas
• Maintain a minimum of 15 air changes per hour, with at least three being fresh air
• Appropriate filters (as recommended by the American Institute of Architects) should be used for filtration of all air, whether recirculated or fresh
• Air should enter through the ceiling and exit near the floor
• Keep operating room doors closed except for necessary entry
• The use of ultraviolet lamps in the theater is not necessary as a deterrent of SSI
• Prior to subsequent procedures, visibly soiled surfaces should be cleaned with Environmental Protection Agency (EPA)–approved disinfectants
• After a contaminated or dirty procedure, special cleaning or closure of the operating suite is not necessary
• Use of tacky mats prior to entry in the operating suite is not necessary
• Sterile surgical instruments and solutes should be assembled just prior to use
• All surgical instruments should be sterilized according to guidelines; flush sterilization should only be used for instruments that are required for immediate patient use

Category II recommendations include the following:

• Limit the number of personnel entering the operating suite.
• Orthopedic implant surgery should be performed in an ultraclean-air environment.
• Wet-vacuum the floor of the operating theater at the end of day/night using an EPA-approved disinfectant

Special situations

Elective colon surgery

Bowel surgery results in the breakdown of the protective intestinal mucous membrane, with release of the facultative and anaerobic bacteria that heavily colonize the distal small bowel and colon. Eradication of aerobes and anaerobes is necessary to reduce infective complications following intestinal procedures. Mechanical cleansing and antibiotics could achieve this.

Mechanical cleansing can take the form of dietary restrictions; whole gut lavage with one of several preparations, such as 10% mannitol solution, Fleet's phospho-soda, or polyethylene glycol, usually is performed on the day of surgical intervention. Enteral antibiotic regimes to eradicate intrinsic bowel flora vary, with oral neomycin and erythromycin being the most popular combination in the United States. Other combinations with neomycin include the use of metronidazole and tetracycline. Prophylactic parenteral antibiotics also are used with the above.

Intravascular device-related infections

Intravascular devices are of vital use in daily hospital practice. They are used for the parenteral administration of fluids, blood products, nutritional fluids, and medication and for access in hemodialysis; equally important is their use in the monitoring of critically ill patients.

Unfortunately, because the use of these devices constitutes an invasive procedure, they are associated with infectious complications that could be of a local or systemic nature. Recommendations for prevention ^[33] and treatment ^[34] are available to limit their associated morbidity and mortality (which could be as high as 20% in patients with catheter-related bloodstream infections).

In a double-blind, randomized, controlled study of 400 patients with nontunnelled central venous catheters, Dettenkofer et al investigated the effectiveness of the antiseptic octenidine dihydrochloride, used in combination with alcohol-based antiseptic, against infection at central venous catheter insertion sites. ^[35] One group of patients received skin disinfection with 0.1% octenidine with 30% 1-propanol and 45% 2-propanol, while a control group was disinfected with 74% ethanol with 10% 2-propanol.

In this study, microbial skin colonization at the catheter insertion site and positive microbial cultures at the catheter tip were significantly reduced in the octenidine group. ^[35] No significant differences in catheter-associated bloodstream infections were found between the groups.

Although the goal of every surgeon is to prevent wound infections, they will arise. Treatment is individualized to the patient, the wound, and the nature of the infection. The operating surgeon should be made aware of the possibility of infection in the wound and determine the treatment for the wound.

Ideally, surgical care should start with meticulous detail to strategies that prevent the development of SSIs in the first place. Preoperatively, attention should be paid to factors like optimization of patient status, proper asepsis, and surgical site preparation. Intraoperatively, adherence to good basic surgical principles of minimal and fine tissue dissection, proper selection of suture materials, and proper wound closure is important.

If a SSI sets in, the treatment often involves opening the wound, evacuating pus, and cleansing the wound. The deeper tissues are inspected for integrity and for a deep space infection or source. Dressing changes allow the tissues to granulate, and the wound heals by secondary intention over several weeks. Early/delayed closure of infected wounds is often associated with relapse of infection and wound dehiscence.

Additional preventive strategies

Evidence shows that the close regulation of blood sugar may be a major determinant of wound morbidity. ^[36] Although investigators have vigorously pursued for decades the identification of a specific innate or acquired immune deficiency among patients with diabetes, it may be the blood sugar that is the determinant of infection for these patients.

A second issue of considerable interest is body temperature. A prospective randomized study demonstrated that failure to maintain intraoperative core body temperature within 1-1.5°C of normal increases the SSI rate by a factor of 2. ^[37] It raises the scientific question of whether increasing core temperature during operations over normal temperature might in fact protect against infection.

A third issue is oxygenation. ^[38] The fresh, hemostatic surgical incision is a hypoxic, ischemic environment. Maintaining or increasing oxygen delivery to the wound by increasing the inspired oxygen concentration administered to the patient perioperatively has also been shown to reduce the incidence of SSIs. It is presumed that increased oxygen availability is a positive host factor, perhaps via enhanced production of oxidant products that facilitate phagocytic eradication of microbes.

A strategy that could bear fruit for preventing SSIs in the future is the establishment of dedicated infection surveillance units in hospitals with the aim of accomplishing the following:

• Identify epidemics by common or uncommon organisms
• Establish the correct use of prophylaxis (ie, timing, dose, duration, choice)
• Document costs, risk factors, and readmission rates
• Monitor postdischarge infections and secondary consequences
• Ensure patient safety

A major concern is how to prevent or minimize the emergence of resistance. Although resistance is not a new phenomenon, the incidence has increased dramatically over the past two decades. The development of new drugs has slowed considerably and may be unable to keep pace with the continuing growth of pathogen resistance.

Accordingly, effective strategies are needed to prevent the continuing emergence of antimicrobial resistance. These strategies include avoiding unnecessary antibiotic administration and increasing the effectiveness of prescribed antibiotics, as well as implementing improvements in infection control and optimizing medical practice.

Although an SSI rate of zero may not be achievable, continued progress in understanding the biology of infection at the surgical site and consistent applications of proven methods of prevention will further reduce the frequency, cost, and morbidity associated with SSIs.