Wound infection rates following clean operative procedures: can we assume them to be low?

Postoperative wound infection rates have historically been reported to be lower following clean operative procedures than for other traditional categories of surgery.1-2 This was thought to be due primarily to the low levels of exogenous contamination that occur during these procedures, as contrasted to the higher combination of exogenous-endogenous contamination that occurs during other surgical procedures. Over 500,000 wound infections are estimated to occur nationally each year, approximately 2.8 per 100 operations performed.3 At least 50% of these infections will take place after hospital discharge in this age of outpatient and same-day surgery.45 Standardized effective surveillance programs to detect and control surgical wound infection have been proven to be beneficial in reducing their incidence.5 In the mid 1970s, the development of postoperative wound infection, following commonly performed operative procedures, was noted to be associated with a doubling of the average duration of hospital stay and, correspondingly, significant increases in the cost of hospitalization.6 Today, these increases in real cost and length of hospital stay are undoubtedly much lower for most wound infections because of the fact that most surgical procedures are accomplished in the outpatient setting. Wound infections diagnosed in this setting usually do not require hospital admission and are treated in the outpatient clinic or in the patient's home.? An exception to this can be cited for sternal wound infections following cardiac operations that continue to have a dramatic impact, increasing the duration of hospitalization as much as 20-fold and the cost of hospitalization five-fold.8 The pathogens usually isolated from surgical wound infections following clean surgical procedures continue to be exogenous, aerobic, gram-positive cocci typified by Staphylococcus aureus. Rarely, however, unusual microorganisms such as rapidly growing mycobacteria, Rhodococcus bronchialis, and Candida tropicalis have been implicated in outbreaks of both superficial and deep wound infections following open heart surgery or augmentation mammoplasty.9-12 The absolute prevention of postoperative wound infection seems to be an impossible goal. The attainment of low rates depends on many factors including good surgical judgment and proper technique as well as the general health and stage of disease of the individual patient. Many other factors such as length of preoperative stay, techniques of preoperative cleansing and hair removal, use of prophylactic abdominal drainage, and the presence of remote infection at the time of elective operation significantly influence the development of postoperative wound infections in clean surgery.2,13 The use of prophylactic antibiotics in clean surgical procedures that use a prosthesis or foreign body is generally advocated.14-15 There is debate, however, concerning the use of prophylactic antibiotics in clean surgical procedures that do not use foreign materials such as in most breast operations and hernia repairs.14-16 What incidence of wound infection should one assume to be acceptable in clean surgical procedures? Should it be the time-honored 2% or below?' Should we assume that all patients undergoing a clean surgical procedure have an equally low risk for the development of postoperative wound infections? In this issue of Infection Control and Hospital Epidemiology, Ferraz and colleagues discuss their 13-year study of the incidence of postoperative wound infection in 1,542 patients undergoing clean surgery.17 They have identified a great variation in the incidence of infection for the different procedures studied. The lowest infection rate was 4.7% in inguinal hernia repair, while the highest infection rates were observed following the repair of an abdominal incisional hernia (14.7%) and in