February 06, 2024
4 min read
Surgical site infections, or SSIs, are among the most prevalent and pesky health care-associated infections. Roughly 1% to 3% of patients will develop an infection near or at the incisional site following surgery.
Ranging from superficial wound infections to those involving the deep tissues and organs, SSIs cost an estimated $3.5 billion to $10 billion annually in the United States and often result in longer hospitalizations and reoperation. However, 60% of SSIs are preventable.
SSIs are likely to be caused by bacteria inoculated into the incision at the time of surgery. Between 70% to 95% of pathogens are from the patient’s endogenous flora. These pathogens vary by surgical location, with the most common being components of skin flora, like Staphylococcus aureus and Streptococcus species. In gastrointestinal surgeries, some SSIs may involve enteric organisms, such as Escherichia coli. Exogenous transmission via surgical personnel or heater-cooler units can also lead to infections.
Updated recommendations published last year outlined essential practices shown to minimize SSI development. The recommendations include assessing patients for beta-lactam allergy, avoiding the use of routine vancomycin prophylaxis and discontinuing antibiotics after closing the incision.
Assessing for beta-lactam allergy
One potentially modifiable patient-specific risk factor for SSIs is a listed beta-lactam allergy. A new essential practice in preventing SSIs is conducting beta-lactam allergy assessments.
Cefazolin, a first-generation cephalosporin, is a preferred perioperative antibiotic for many surgeries because of its activity against common skin flora and ability to rapidly reach optimal concentrations in tissues. For the 10% of patients with a self-reported penicillin allergy, non-beta-lactam antibiotics — such as clindamycin or vancomycin — are often administered as alternatives despite evidence showing that 90% to 99% of patients with a reported penicillin allergy do not have a true immediate hypersensivity.
Additionally, 80% of patients with immunoglobulin E-mediated penicillin allergy lose their sensitivity after 10 years. Cefazolin does not share an identical or similar side chain to penicillin derivatives, posing a less than 3% risk for cross-reactivity.
Thorough allergy assessments take time to interview the patient and document findings, making a pre-procedure outpatient appointment an optimal opportunity. Workflows in the acute setting on the day of surgery may pose challenges for clinicians in gathering all allergy history details.
A risk-stratification approach targeting patients with immediate hypersensitivity or unknown reaction is one strategy to improve antibiotic selection. Another strategy that my health system implemented due to a clindamycin injection shortage in 2023 was auto-subbing clindamycin perioperative orders for cefazolin.
Optimizing antibiotic prophylaxis for surgery lessens the risk for Clostridioides difficile infection and emergence of multidrug-resistant organisms like MRSA and vancomycin-resistant Enterococcus. The antibiotic prophylactic agent choice combined with timing of administration in relation to surgery are imperative modifiers in SSI risk reduction.
Avoiding routine vancomycin prophylaxis
Vancomycin is not a first-line prophylactic antibiotic option except for specific scenarios. These scenarios include patients with known MRSA colonization, especially if surgery involves prosthetic material, and in the setting of a proven outbreak of SSIs due to MRSA. High suspected rates of MRSA SSI is not justification to use vancomycin perioperatively.
Vancomycin appears to have less activity against methicillin-susceptible S. aureus compared with beta-lactams and lacks gram-negative activity. In a study of over 79,000 surgical procedures, vancomycin was associated with significantly higher risk for acute kidney injury (AKI). In addition, the rate of SSIs between beta-lactam prophylaxis and vancomycin was not different in two meta-analyses.
Researchers have also studied the role of combination vancomycin plus beta-lactam prophylaxis. In a large cohort of 70,101 surgeries, vancomycin plus beta-lactam combination prophylaxis was associated with a greater risk for AKI compared with vancomycin alone. The same study showed that vancomycin plus beta-lactam reduced the incidence of SSIs following cardiothoracic procedures compared with antibiotic prophylaxis monotherapy. A reduction in SSI rates was not seen for orthopedic, vascular, hysterectomy or colorectal procedures.
A comprehensive risk-benefit assessment is needed before employing combination antibiotic prophylaxis that includes vancomycin.
Discontinuing antibiotics after incision closure
One of the major changes between the 2014 and most recent SSI prevention guidelines was the addition of a recommendation to stop antimicrobial therapy after the incision is closed in the operating room.
Previous guidance recommended stopping antibiotic prophylaxis within 24 hours of surgery. Presently, there is no evidence that antibiotic therapy given after incisional closure reduces SSIs, even when drains are inserted during the procedure, and prolonged durations are increasingly associated with patient harm, such as AKI.
A systematic review of 28 randomized trials that included 9,478 patients who received either a single dose or multiple doses for prophylaxis showed that multiple prophylactic doses did not reduce the risk for SSIs. Although this review did not include orthopedic surgeries, a single-center, retrospective cohort study investigated patients who underwent joint arthroplasty and received a single dose of antibiotic prophylaxis — no additional doses after skin closure — or 24-hour antibiotic duration determined there were no differences in prosthetic joint infection, superficial infection, 90-day reoperation or 90-day complications.
Other strategies for SSI prevention
Preventing SSIs takes a coordinated approach with a cohesive, multidisciplinary team across the preoperative, intraoperative and postoperative periods. The relatively low incidence of SSIs makes conducting randomized controlled trials challenging.
Numerous other strategies have been recommended by international organizations to decrease SSIs. However, only six key components are supported by evidence from randomized trials. Avoiding razors for hair removal was associated with a lower rate of infection (4.4% with razors vs. 2.5% with clippers). Another infection-lowering intervention is decolonization with intranasal antistaphylococcal agents and antistaphylococcal skin antiseptics for high-risk procedures (0.8% with decolonization vs. 2% without). In addition, the use of chlorhexidine gluconate and alcohol-based skin preparations, maintaining normothermia, and perioperative glycemic control are all supported by randomized controlled studies to decrease SSIs.
Reducing SSIs is a priority. Not only are SSIs linked to significant morbidity and mortality, but they also impact perceptions of the quality of care. Adoption of essential practices in the latest guideline ensures appropriate perioperative antibiotic selection, timing and duration. Complete assessment of beta-lactam allergies may avoid routine perioperative antibiotic agents like vancomycin and clindamycin. Together with stopping prophylactic antibiotics at incision closure, it lessens the risk for adverse events.
Sometimes less antimicrobial prophylactic therapy is more, when thinking of spectrum coverage and duration. The best treatment of SSIs is prevention.
For more information:
Jennifer Ross, PharmD, BCIDP, is an infectious diseases clinical pharmacist at M Health Fairview – University of Minnesota Medical Center. Ross can be reached at email@example.com.