Preventing Surgical Site Infections

What have we learned about preventing surgical site infection since 1867 when Lister first prevented surgical site suppuration and septicemia by using carbolic acid to wash wounds, soak dressings, and spray operating room air? In an experiment that laid the foundation for modern surgery,¹ 9 of Lister’s 11 compound fracture patients healed without amputation or mortality typical of that era. Do we know today which of Lister’s precautions was effective? Carbolic acid was soon replaced with less irritating aseptic technique. More recently, gentler topical antimicrobials with sustained delivery like mupirocin, cadexomer iodine, or ionic silver have been added to the antimicrobial armamentarium. Today, it is surprising how little we know regarding effective usage parameters of antimicrobial agents in preventing surgical site infections (SSI) or their benefits and drawbacks. A Cochrane review,² discussed in the April 2008 Evidence Corner, found some evidence that cadexomer iodine improved venous ulcer healing, but concluded that further research would be needed to make a definitive conclusion. Antimicrobial agents still require more evidence for optimally safe, effective usage in surgical wound care. The two recent articles featured in this Evidence Corner give us a surprising view of surgical drape safety and efficacy and offer tentative hypotheses regarding steps to prevent SSI with methicillin-resistant Staphylococcus aureus (MRSA).

Reference: Webster J, Alghamdi AA. Use of plastic adhesive drapes during surgery for preventing surgical site infection. Cochrane Database Syst Rev. 2007;(4):CD006353.

Rationale: Surgical site infection (SSI) occurs in an estimated 15% of clean surgeries and 30% of contaminated surgeries. Plastic adhesive drapes with and without antimicrobial agents is a popular method of protecting the wound from SSI, but conflicting results place their efficacy in question.

Objective: Conduct a Cochrane review of evidence supporting efficacy and cost effectiveness of surgical drapes in preventing SSI, mortality, and morbidity.

Methods: MEDLINE, Ovid, and Cochrane databases were searched through April 2007 for randomized controlled trials (RCTs) comparing a plastic adhesive drape with no adhesive drape, used alone, or with woven or paper materials on patients undergoing any type of surgery. Two authors independently reviewed each publication and abstracted method and results sections. Outcome measures included SSI incidence, cost, mortality, morbidity, and length of hospital stay (LOS).

Results: In 5 studies involving 3082 participants comparing adhesive drape use with no drape, more patients who were managed with the adhesive drape developed a SSI (P = 0.03). Combined analysis of two studies with 1113 participants found no difference in SSI between groups (P = 0.89) managed with an iodine-impregnated adhesive drape compared to no drape. Adhesive drape use did not affect LOS.

Authors’ Conclusions: Based on the 7 RCTs qualifying for analysis, there is no evidence that plastic adhesive surgical drapes reduce SSI, and some evidence that these drapes increase SSI rates unless impregnated with iodine. Further RCTs are needed using blinded outcome assessment of SSI on wounds with different SSI risk classifications, such as depth and level of contamination.

Reference: van Rijen MM, Kluytmans JA. New approaches to prevention of staphylococcal infection in surgery. Curr Opin Infect Dis. 2008;21(4):380–384.

Rationale: Surgical patients carrying nasal Staphylococcus aureus (SA) have increased risk for nosocomial SSI. Identifying and implementing effective protocols for preventing SSI caused by either methicillin-sensitive (MSSA) or methicillin-resistant Staphylococcus aureus (MRSA) may improve surgical patient outcomes.

Objective: Review evidence of safety, efficacy, and cost effectiveness for approaches for preventing SSI with MSSA or MRSA in surgical patients, and identify the most effective means of preventing these SSI.

Methods: Literature published from August 2006 through January 2008 was reviewed to determine the efficacy of approaches for reducing nosocomial SSI, including subsets with MSSA or MRSA. Methods reviewed included: 1) nasal SA screening of all patients and subsequent isolation of MRSA carriers; 2) systemic vancomycin antibiotic prophylaxis for all identified MRSA carriers; 3) decolonization the nasopharynx or oropharynx of confirmed SA carriers with mupirocin or 0.12% chlorhexidine gluconate washes followed by use of chlorhexidine soap; 4) treat all patients to prevent SA infections. Measures included cost per SSI or death prevented, LOS, nosocomial SSI incidence, including subset analyses of those infected with MSSA and MRSA, were the primary outcomes measured. Primary measures included cost per SSI or death prevented, LOS, nosocomial SSI incidence, including subset analyses of those infected with MSSA and MRSA.

Results: Risk factors for MRSA SSI included nasal MRSA colonization, and if the patient originated from an external department or facility. Effective strategies for reducing MRSA SSI risk included pre-operative nasal MRSA screening followed by systemic prophylaxis with cefazolin in patients not at MRSA risk, or isolation of MRSA nasal carriers plus systemic vancomycin. Adding topical chlorhexidine gluconate decolonization reduced the overall nosocomial infection rate, but did not affect SA SSI rates. Nasal mupirocin ointment reduced SA nosocomial infections but not SSI of nasal MRSA carriers. It was most cost effective in preventing SA infections and deaths to screen and treat nasal MRSA carriers than to treat all surgical patients, which was in turn more cost effective than to avoid both screening and treatment for all patients.

Authors’ Conclusions: Focused decolonization of MRSA using topical nasal mupirocin ointment and chlorhexidine cleansing, combined with appropriate systemic antibiotics, may be an effective strategy for preventing SSI with MRSA. A prospective, randomized, placebo-controlled trial is needed to evaluate the efficacy of this strategy in confirmed MRSA carriers.

Clean, technically excellent technique,³ appropriate perioperative systemic antibiotics,⁴ and special attention to each patient’s risk factors such as obesity, nicotine use, nutritional, physiologic, metabolic, or disease challenges,^4,5 are essential for optimizing host immune function and preventing SSI. The two articles reviewed here build on these precepts. Surprisingly, an adhesive drape may detract more from clean surgical technique than it adds—unless it is impregnated with an effective antimicrobial agent.

Webster and Alghamdi recognized the limitation that their study combined all levels of important risk factors for SSI. For example, what if surgical drapes work on clean wounds, but not on dirty or infected wounds? What if these drapes work on superficial but not deep surgery sites? Proper analysis of such SSI risk factors, which all clinicians face, will help create clinically relevant protocols. The work by van Rijen and Kluytmans, though limited by the brevity of the search timeline, suggests tentative steps toward protocol development for preventing MRSA infection, recognizing that MRSA carriers or high-MRSA environments require special SSI prevention measures. Effective decisions deal with the patient, the environment, and organism factors in a carefully choreographed dance with clinical realities. While both works require further research before definitive conclusions can be drawn, each is a step toward further clarity in preventing SSI.

Laura Bolton, PhD, FAPWCA
Adjunct Associate Professor
Department of Surgery, UMDNJ

WOUNDS Editorial Advisory Board Member and Department Editor