Surgical delivery systems and personnel work under the assumption that nearly all SSI are preventable. Preventing SSI involves eliminating or minimizing known risk factors, including both host and environmental factors. Modern surgical practice includes standardized procedures specifically designed to prevent SSI (Table 69–4). As these procedures are based on a large amount of data accumulated over many years as well as many ongoing studies, one can expect changes as practices evolve in response to new information. Likewise, the practices described are based on studies that included predominantly adults and therefore require certain modifications when applied to children.
Modern operating theater systems are designed to control environmental infectious risk factors and are aimed principally at the reduction of the number of microorganisms that come into contact with the surgical wound. First and foremost is the concept of aseptic technique. Most surgical instruments can be sterilized in an autoclave, which uses superheated steam under pressure to kill organisms and destroy spores. Optical equipment and electrical appliances are damaged by autoclaves and need to be sterilized ethylene oxide gas or peracetic acid. All drapery and consumable materials such as gauze sponges and suture material are also sterilized. Modern operation theaters have ventilation systems that create positive pressure within the room and fresh filtered air is brought in using laminar flow technology to prevent air turbulence. Surgical personnel are required to apply an antiseptic on their hands and forearms and to wear surgical caps, surgical scrub garments, sterile gowns, surgical masks, and sterile gloves. A methodical and almost ritualized behavior is displayed by all personnel to prevent contamination of the surgical field, which includes a complete covering of the patient and operating table with sterile drapes and towels and meticulous attention to potential contamination.
The skin of the patient is prepared with an antiseptic solution, typically applied in concentric circles starting at the incision site and working outward. Betadine (povidone–iodine) is the traditional and still the most widely used operative antiseptic. It has a broad spectrum of activity, including gram-positive and gram-negative bacteria, Mycobacterium tuberculosis, fungi, and viruses, is easy to apply, is relatively inexpensive, and well-tolerated by most individuals.41 Isopropyl (or ethyl) alcohol (70% v/v in water) has a similar spectrum of activity, is easy to apply and dries completely; it is also inexpensive and generally well-tolerated. However the use of alcohol is limited, and in some cases prohibited, due to its flammability. Patient fires have been reported when the alcohol has not been allowed to dry completely before electrocautery is used during surgery. Recently there has been a trend toward the use of chlorhexidine gluconate as a substitute for betadine, especially for skin antisepsis prior to central venous access.42 It is usually supplied in an isopropyl alcohol base and has a broad spectrum of activity and has the advantage of being effective after a single application. It is currently more expensive than betadine, may cause a skin rash in susceptible individuals, and must be allowed to dry completely before starting the operation because of the risk of fire from the alcohol component. In practice, there is no perceptible difference in the incidence of infection regardless of which of the commonly used antiseptics is used. Furthermore, a recent large meta-analysis of available studies failed to show a significant advantage of one antiseptic over another.43
Prior to application of antiseptics, the skin of the patient may need to be prepared in other ways. Excessive hair is usually removed prior to making an incision. It is best to clip the hair close to the skin rather than using a shaving razor, which has been shown to increase the risk of SSI,44 and hair should be removed as close to the time of surgery to avoid the creation of folliculitis. Showering with an antiseptic soap the night before a scheduled operation was formerly a time-honored ritual but has been shown to have no effect on the incidence of SSI.45 Similarly, mechanical bowel preparation with cathartics and oral antibiotics was the inviolable rule before elective colorectal surgery for decades but has been shown not only to be ineffective in preventing SSI but may actually increase the risk of anastomotic leak and organ-space infection.46,47
One of the most important interventions in the prevention of SSI is the use of prophylactic antibiotics.48–52 It might seem obvious that the administration of antibiotics to patients felt to be at high risk of SSI would prevent infection, and for the most part this is true. However, there are limitations to the effectiveness of prophylactic antibiotics and there are risks involved as well. Current recommendations are summarized in Table 69–5. Patients with infected wounds are treated with appropriate antibiotics and are technically not given “prophylactic” antibiotics. For clean wounds, it is difficult to show a benefit from antimicrobial prophylaxis and the risks, including anaphylaxis and the generation of resistant organisms, may outweigh any small potential benefit. The exception is a clean operation that involves the placement of an implant, such as a heart valve or bone endoprosthesis, or in certain parts of the body, such as the heart, brain, or bone, in which case even a single infection can have deleterious consequences. Although generally not indicated or recommended in most cases, it is nevertheless common practice in some centers to use prophylactic antibiotics routinely in all clean cases because of a perceived decrease in the albeit small number of SSI that are seen in these patients.
Table 69–5. Antibiotic Prophylaxis Recommendations9,51,52 ||Download (.pdf)
Table 69–5. Antibiotic Prophylaxis Recommendations9,51,52
Recommended Antibiotic Regimen
S. aureus, coagulase-negative staphylococci
Less common: gram-negative rods noncardiac thoracic: also Streptococcus pneumoniae
- None, or
- Cefazolin or Cefuroxime, plus
- Vancomycin or Clindamycin, if β-lactam allergic
Gram-negative rodsLess common: S. aureus, coagulase-negative staphylococci
Gram-negative rods, enterococcus, anaerobes
The greatest benefit of antimicrobial prophylaxis is for clean-contaminated and contaminated wounds. The choice of antibiotic should reflect the most likely organisms to be encountered and therefore should cover aerobic gram-positive organisms. Coverage for gram-negative bacteria and/or anaerobes should be provided for operations involving exposure to the aerodigestive tract or bowel flora. For prophylaxis to be effective, there should be adequate tissue levels of the antibiotic at the time the incision is made. Antibiotics should therefore be given within 60 minutes prior to the start of the operation, rather than at the time of incision (too late) or “on call” to the operating room (too soon), as was customary in the past. Nearly every study has shown that a single preoperative dose of an appropriate antibiotic is effective in decreasing the incidence of SSI. There are very little data to support the use of antibiotics for the first 24 hours and no data to support their use for more than 1 day after an operation.48,49
In addition to efforts designed to minimize contamination of the surgical wound, surgeons have long been taught that careful management of the wound during an operation can lower the risk of SSI. First and foremost is gentle handling of tissues. Infections are more likely to develop in wounds in which the skin edges are devascularized and in the presence of devitalized tissue. Wound edges are grasped carefully with noncrushing forceps or skin hooks and only when necessary. Prior to skin closure, the wound is irrigated with sterile normal saline to wash away necrotic debris. Efforts should be made to avoid maneuvers that may decrease the blood supply and delivery of oxygen to the operative field, including unnecessary or poorly designed tissue flaps and the application of dressings that create pressure on the wound or generate a tourniquet effect.
Wound Closure and Postoperative Care
Wound closure is also an important concept in the prevention of SSI. An incision that is infected or grossly contaminated may be treated with one of several techniques. Wounds may be closed with the placement of drains to prevent an infected fluid collection from forming. Closed-suction drains (e.g., Jackson–Pratt or Hemovac drains) decrease the risk of infections while passive drains (e.g., Penrose drains) that are brought out through the incision are not recommended as they have been shown to increase the risk of SSI.9,53 Finally, in the case of dirty or frankly infected wounds, it is recommended that the wound not be closed at all, and instead is left open and lightly packed with moistened sterile gauze. Options then include (1) delayed primary closure, in which the surgical dressing is left undisturbed for 2–3 days after which the wound edges are brought together primarily in sterile fashion and (2) wound closure by secondary intention, in which the dressings are changed two to three times daily using sterile technique and the wound is allowed to granulate and heal over the course of 2 to several weeks. Some wounds of intermediate risk for SSI pose something of a dilemma regarding the decision to use closed or open wound management. For example, adults who undergo colostomy closure or appendectomy for perforated appendicitis have historically been treated with open wound management due to an expected 50% or greater risk of wound infection, while pediatric surgeons generally utilize primary closure for such wounds because the true incidence of SSI in these circumstances appears to be much lower.54
Although most SSI are thought to be caused by intraoperative wound contamination, some may be due to postoperative contamination or the use of surgical dressings that create a local environment conducive to the growth of microorganisms. Wounds that are near the anus or a colostomy should be protected from fecal effluent with barrier dressings or left open to heal by secondary intention. In rare cases, complex wound closures of the buttocks or perianal region are protected by temporary fecal diversion. For most other incisions, it was long felt that a surgical dressing should be placed sterilely in the operating room and then removed after a few days to allow the wound to “breathe.” The patient was asked to keep it dry for at least a week. Over the past 10–15 years, these recommendations have all but vanished. Modern dressings are usually “occlusive,” not permitting tissue fluid to escape and protecting the wound from exogenous pathogens, and are not removed for 7–14 days, with no increase in the incidence of wound infection. Most popular dressings are also transparent (Tegaderm, Dermabond) allowing clinicians to monitor the wound for signs of infection.