Enturia

34. Current Approaches for the Prevention of Surgical Site Infections

Florman S, Nichols R L Tulane Abdominal Transplant Institute, Tulane University School of Medicine, New Orleans, Louisiana Department of Surgery, Tulane University School of Medicine, New Orleans, Louisiana. Current Approaches for the Prevention of Surgical Site Infections. Am J Infect Dis 3 (1): 51-61, 2007.

Background
Surgical site infections (SSIs) are the most common type of nosocomial infection among surgical patients and are commonly caused by the patient's own microbial flora. The prevalence of SSI is a major concern because of the associated increase in the incidence of morbidity and mortality, length of hospitalization and cost of care for postoperative patients. Key factors that determine whether patients are at risk for developing SSI include the inherent potential contamination of the surgical site, the duration of the operation and the individual patient susceptibility. Preventive preoperative measures that can reduce the risk of SSIs include administration of antimicrobial prophylaxis, proper utilization of skin antiseptic agents for the patient and the surgical team, proper patient preoperative hair removal and the policy of canceling elective procedures when remote skin, urinary, or pulmonary infections occur.

Methods
This paper is a review on the efficacy and safety of available antiseptic agents, as well as a discussion of patient-specific prevention strategies.

Microbiology
Effective perioperative care is imperative for the prevention of SSIs and must address the microorganisms most likely to be encountered during the planned procedure. The pathogens responsible for SSIs vary depending on the type of surgery but are usually microorganisms found on or present within the surgical patient. For example, S. aureus from the patient’s own skin microbial flora is the most common pathogen isolated from postoperative wound infections in clean surgical procedures (Class I). In general, S. aureus, coagulase-negative staphylococci, Enterococcus species and Escherichia coli (E. coli) are the most frequently isolated pathogens in SSIs and the presence of each is determined primarily by the anatomical location and inherent contamination of the surgical site. In clean contaminated (Class II), contaminated (Class III) and dirty-infected (Class IV) surgical procedures, different risks are present for exposure to pathogens. The diverse endogenous microbial flora that normally inhabit the surgically violated organs are the microorganisms most frequently isolated from these postoperative surgical wounds. Gram-negative bacteria, including E. coli and anaerobic Bacteroides fragilis, predominate in many of these postoperative wound infections.

Results

• Preoperative skin preparation: The preoperative skin preparation of both the patient and the surgical team are essential in the prevention of SSIs. The mainstays of these recommendations are preoperative showering and skin antisepsis of the patients and scrubbing for the surgical team. These recommendations are all classified as CDC category IB (i.e., strongly recommended and supported by some experimental and clinical evidence).
• Preoperative showering: Because most SSIs are associated with skin flora, the CDC strongly recommends preoperative showering by the patient the day before surgery. Showering with an antiseptic or detergent agent can significantly decrease skin microbial counts. Using chlorhexidine has been shown to reduce skin bacterial counts as much as nine-fold, whereas povidone-iodine and triclocarban soap reduced skin bacterial counts 1.3-fold and 1.9-fold, respectively. Furthermore, the overall incidence of SSIs has been observed to be lower when chlorhexidine is used for preoperative showering (9%) than for those patients that showered with bar soap or placebo (12.8 and 11.7%, respectively). In these patients, the incidence of S. aureus infections in clean procedures was reduced by half in patients who showered with chlorhexidine compared with bar soap.
• Skin antisepsis:
  • An optimal antiseptic agent must reduce the initial microbial count and have persistent inhibition of microbial growth during the course of the surgical procedure. In addition, the antimicrobial action should be effective in the presence of blood.

Multiple studies have shown that CHG and CHG/alcohol solutions display these important properties.

• CHG plus 70% isopropyl alcohol (IPA) has demonstrated efficacy against a wide range of bacteria, including P. aeruginosa, S. aureus and antibiotic resistant bacteria
• Furthermore, CHG/IPA exhibits a rapid onset of action, persists for up to 24 hours and has increased efficacy with repeated applications
• Chlorhexidine is not inactivated in the presence of blood, which neutralizes the effects of iodine and PCMX and dilutes the effects of alcohol

The combination of these parameters makes CHG containing agents more effective than many other antiseptic agents at reducing skin and wound microbial counts and thus decreasing SSIs.

• Preoperative scrubbing:
  • The surgical hand scrub should display efficient, broad-spectrum antimicrobial properties on intact skin and contain a nonirritating, fast-acting antimicrobial preparation.

Surgical scrub solutions containing CHG have greater antimicrobial activity compared with other antiseptics. CHG products demonstrate a significant immediate and persistent antimicrobial effect, giving them a theoretical advantage during long surgical procedures.

• In a study comparing scrubbing regimens of CHG/alcohol with povidone-iodine, the CHG regimen resulted in a >50-fold reduction in hand bacterial counts. In contrast, the povidone-iodine scrub reduced counts by more than three-fold.
• In a similar study of 39 volunteers, scrubbing with CHG/alcohol solutions resulted in a significantly greater reduction in bacterial count compared with povidone-iodine and chloroxylenol scrubs at all sampling times, up to six hours after application (P < 0.01)

Additional Pre- and Perioperative Considerations

• Preoperative hair removal: The practice of shaving to remove hair from the surgical site the night before an operation is associated with a significantly higher risk for SSI compared with the use of a depilatory agent or no hair removal at all. Therefore, it is recommended that hair removal be avoided. However, if hair removal is necessary, the use of clippers or depilatory agents is preferable over shaving to reduce the risk of surgical site contamination.
• Pre- and perioperative glucose control: Inadequate control of glucose levels in surgical patients with diabetes is a predictive factor for the development of SSIs.
• Preoperative tobacco cessation: Patients should be encouraged to abstain from cigarettes, cigars, pipes, or any other form of tobacco for at least 30 days before surgical procedures.
• Operative normothermia: Intraoperative hypothermia impairs immune function by causing vasoconstriction and a reduction in blood flow to surgical sites, which results in an increased susceptibility to SSIs. It decreases the delivery of oxygen to tissues and inhibits the oxidative killing of pathogens by neutrophils.
• Perioperative hyperoxia: Neutrophils use a method of oxidative killing to combat pathogens. This mechanism is compromised during surgical procedures because of a reduction in oxygen delivery to the tissues. All operations disrupt the vascular supply at the surgical site, causing the wound to become hypoxic compared with normal tissue. Therefore, the supplemental administration of oxygen during surgical procedures may counterbalance the surgery-related hypoxia and reduces the risk for SSIs.

Conclusions
A comprehensive, multimodal approach is necessary for the effective prevention of SSIs. Accepted methods for reducing the incidence and severity of SSIs, which include procedures for patients and healthcare providers, may be underutilized in many settings. Existing CDC guidelines for the use of antimicrobial prophylaxis, preoperative skin preparation for the patient and surgical team and perioperative practices provide evidence-based standards for effective preventive strategies. Implementation of CDC guidelines in all surgical and medical departments should be a priority, as there is significant potential to improve patient outcomes and to decrease hospital costs associated with preventable infections in surgical sites.

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