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What are the clinical data surrounding irrigation methods for the prevention of wound infections?

Debridement and irrigation of wounds, both surgical and those secondary to trauma, have been utilized for centuries to reduce the incidence of bacterial infection.¹ Although wound irrigation is common practice, there is a lack of literature and guidelines to advise the ideal method of administration. All wounds are considered contaminated and wound irrigation may be implemented to remove bacteria and promote proper healing.² In theory, the use of a local agent to irrigate a wound would be superior to systemic therapy because localized concentration could be significantly higher than levels achievable with systemic treatment, leading to improved bactericidal and bacteriostatic activity.³ Tap water and normal saline used alone may be suitable for wound irrigation; however, it is thought that the addition of additives, to normal saline in particular, may improve wound healing and prevent infection. The optimal additives to prevent or reduce infection rates remain controversial. However, additives such as antibiotics, antiseptics, and/or soaps are commonly utilized.¹ This paper will review the safety and efficacy of antibiotics, antiseptics, and soaps for use as wound irrigations.

Antibiotics work by interfering with cell wall synthesis or altering the cell membrane.^1,4 Dirschi and colleague provide recommendations regarding suitable properties for antibiotics used in irrigations.⁵ These properties include: a wide spectrum of activity; lack of local irritation to normal tissue; low systemic absorption and toxicity; low allergenicity; minimal bacterial resistance; and the ability to be prepared and administered topically. Examples of antibiotics that have been used alone or in combination with others for irrigation purposes are neomycin, bacitracin, polymyxin, cephalothin, and kanamycin.

Antiseptics, including povidone-iodine and chlorhexidine, are active against many bacteria, fungi, and viruses.^1,4 All antiseptics work by damaging the cell wall or membrane, which changes the permeability of the cell. The risk associated with antiseptics is that they may be harmful to host cells, causing damage to intact cells around the area of the wound, which may impair wound healing.

Soaps, also known as surfactants, have been used for many years prior to antimicrobial use. Surfactants contain hydrophilic and lipophillic components.⁴ It is the lipophillic component that blocks the initial stage of bacterial cell adhesion.^1,4 This process decreases the bacterial load in the wound, as opposed to killing the bacteria. Two commonly used surfactants are benzalkonium chloride and castile soap.

Anglen provides recommendations for the use of irrigation additives (see Table 1).⁴ Overall, the utility of these agents is questionable and relatively unproven to be effective.

Literature review
The following table summarizes a spectrum of the literature that evaluates the efficacy of antibiotic, antiseptic, and surfactant additives for wound irrigation. In addition, following the table, is a summary of a study that evaluated systemic absorption of amikacin after wound irrigation without specifically addressing infection prevention rates.

Amikacin, an aminoglycoside antibiotic, was studied by Van Way and colleagues to assess the systemic absorption of amikacin after wound irrigation.¹³ Seventeen patients that had received intraoperative irrigations of the pleura and peritoneum were included in this study. The operative site was irrigated with amikacin 500 mg in 200 mL of normal saline for 3 minutes and then aspirated. The retained dose in the peritoneal cavity was 350 mg + 128 mg and 100 mg + 79 mg in the pleural cavity (p<0.01). The results of this study show that therapeutic plasma levels of amikacin are obtained following interperitoneal irrigation. There was no positive correlation between the dose and the amount of drug retained by the patient. The results of this study demonstrate the systemic absorption of amikacin irrigation; however, the efficacy of preventing infection is not addressed. Therefore, the role of amikacin in wound irrigation has yet to be established.

Conclusion
The evidence supporting the efficacy of wound irrigation is limited. More recent studies suggest that the addition of an antiseptic, such as povidone-iodine, or a surfactant, such as castile soap, may be more beneficial in preventing wound infections compared to normal saline or antibiotic irrigations. The data surrounding antibiotic irrigations specifically are conflicting and efficacy has yet to be established. Therefore, antibiotic irrigations for the prevention of wound infections should not be routinely used.