Preventing Surgical Site Infections
Surgical site infections occur in 2% to 5% of patients having inpatient surgery and result in significant morbidity and mortality.1 These infections are highly preventable. There have been many strategies developed for use before, during, and after surgery to help reduce the risk of surgical site infections. Antimicrobial stewardship programs often target these infections, ensuring their institution’s protocols follow current guidelines. These interventions have resulted in a decrease in surgical site infections. However, they remain the leading healthcare-associated infection. The CDC continues to push for further reductions. Their 2020 target is a 30% reduction of infections from the 2015 baseline.2 This document covers current guidelines and best practices for preventing surgical site infections.
Background
The American Society of Health-System Pharmacists (ASHP), Infectious Diseases Society of America (IDSA), and other groups provide guidelines for preventing surgical site infections.1,3 The World Health Organization (WHO) has also just released recommendations on measures to reduce surgical site infection rates worldwide.4,5 In addition, the Joint Commission has a National Patient Safety Goal to use evidence-based practices for the prevention of surgical site infections. This goal includes educating staff and patients, implementing best practices, monitoring and assessing practices, and measuring surgical site infection rates.6 Preventing surgical site infections is a multidisciplinary goal as there are many intervention targets.
Timing of Antibiotic Administration
Using appropriate antibiotic prophylaxis before and during surgery is one of the more important steps to prevent surgical site infections.
Achieving adequate blood and tissue levels of antibiotics when the surgical site is open is key. Most antibiotics are recommended to be administered within 60 minutes before surgical incision. The exception is antibiotics with longer infusion times, such as vancomycin and fluoroquinolones. These should be administered within 120 minutes before the incision. It is also recommended that antibiotics be redosed after excessive blood loss (more than 1.5 L) or if two half-lives of the drug have passed during surgery. This helps to maintain blood and tissue levels while the surgical site is open.3
Guidelines simplify when to redose antibiotics during longer surgeries. Previous guidance had recommended ranges of time, but current guidelines give specific intervals:3
- Redose cefoxitin and penicillins after two hours;
- Redose cefotaxime after three hours;
- Redose aztreonam, cefazolin, and cefuroxime after four hours;
- Redose cefotetan and clindamycin after six hours.
The time to redose should be measured from the time that the last dose, usually the preoperative dose, was started.3
In most cases, drugs with longer half-lives such as fluoroquinolones and vancomycin will not require redosing. Patients with reduced creatinine clearance may not require redosing of agents that are renally cleared, such as cephalosporins and penicillins.3
Antibiotic Choice and Dosing
Antimicrobial prophylaxis should be selected based on the type of surgical procedure. These choices should be standardized for each type of surgery. Guidelines are comprehensive with regard to recommendations for antibiotics to be used in specific procedures, such as urologic procedures and plastic surgery. Cefazolin is still recommended as the first-line agent for most clean and clean-contaminated surgeries. It provides good coverage of skin flora such as S. aureus, which causes almost one-third of surgical site infections.3
Vancomycin is not a first-line agent for any surgery. However, vancomycin is an alternative to cefazolin (as is clindamycin) for coverage of gram-positive organisms in patients who have had serious reactions to beta-lactams (e.g., anaphylaxis, bronchospasm, urticaria). Vancomycin may also be appropriate prophylaxis in cases where patients are at high risk for MRSA infections or MRSA colonization, or if the patient is already colonized with MRSA.3
Obese patients have an increased risk for surgical site infections. Particular attention should be paid to adequate dosing of antibiotics in these patients. Data show that increasing the dose of cefazolin in obese patients can reduce the risk of surgical site infections compared with lower doses. Using cefazolin 2 g as your surgical prophylaxis dose for all adult patients helps simplify the process and ensure adequate dosing for most patients. In addition, you should ensure patients who weigh more than 120 kg receive cefazolin 3 g.1,3 For gentamicin in obese patients, adults should receive 5 mg/kg based on their ideal weight plus 40% of their excess weight.1
Duration of Antibiotic Therapy
The majority of procedures will require only a single preoperative dose. If antibiotics are given postoperatively however, the duration of this prophylaxis should be no longer than 24 hours in any case.1,3
Previous recommendations for longer durations of prophylaxis after cardiothoracic surgery were not based on good evidence. In addition, there are no data that support prolonged prophylaxis for patients with indwelling drains or intravascular catheters.3 The use of antibiotics for surgical prophylaxis for longer durations than necessary can increase the risk of C. difficile infections, the development of resistance, adverse effects, etc.3
Intranasal Mupirocin
There is debate around the decolonization of S. aureus with intranasal mupirocin in surgical patients. Using mupirocin has been shown to decrease surgical site infections caused by this organism. Rates are decreased when mupirocin is used universally (i.e., administering to all surgery patients), as well as when therapy is targeted to those who have documented nasal colonization with S. aureus (both methicillin-resistant [MRSA] and methicillin-sensitive [MSSA]).7
Universal mupirocin decontamination of all surgery patients is counter to most antimicrobial stewardship directives. It increases costs, likely increases resistance rates, and 70% to 80% of those receiving treatment would gain no benefit.7
Guidelines recommend intranasal mupirocin for cardiac and orthopedic surgery patients who have been screened and found to be colonized with S. aureus. Data show a reduced risk of S. aureus surgical site infections after decolonization in these patients. This recommendation now extends to at-risk patients colonized with S. aureus undergoing other surgeries. Your institution may consider screening surgery patients and decolonizing with mupirocin if they are found to be positive.4 Many institutions are considering this practice if they are having particular issues with S. aureus surgical site infections in certain areas or with certain patients. When used, decolonization with mupirocin should be started five days before surgery.3
Skin Preparation and Cleansing
The source of many surgical site infections are the organisms from the patient’s skin. WHO guidelines recommend patients bathe or shower prior to surgery, using plain soap or an antibacterial soap. Chlorhexidine-containing soaps do not appear to lower surgical site infection rates over plain soap for preoperative bathing.4
WHO does recommend using chlorhexidine-containing antiseptic agents to prepare the surgical incision site. This helps to reduce the patient’s skin microbial flora prior to the incision, reducing the risk of surgical site infections. Chlorhexidine solutions are preferred over povidone-iodine solutions for skin preparation.4
Hyperglycemia
Patients having surgery commonly have a stress response that can result in hyperglycemia both during and after the procedure. This is seen in patients with and without diabetes. Hyperglycemia is associated with in increased risk for surgical site infections. There is some evidence to support controlling blood glucose postoperatively in order to reduce surgical site infections in cardiac surgery patients, as well as patients having other surgeries.5 While reducing hyperglycemia may reduce surgical site infections, the optimal timing and glucose targets have not been defined.5 When hyperglycemia is corrected, it is important to monitor closely in order to avoid hypoglycemia.5
Conclusion
Continue to closely follow recommendations for antibiotic prophylaxis in surgery. Pharmacists play a key role in both recommending appropriate therapy and in facilitating availability of the antibiotics at appropriate and critical times. It is important to choose the right antibiotic which should then be given at the right dose and the right time. Institutions should have established practice guidelines, based on national recommendations, for their healthcare setting.
Project Leader in preparation of this clinical resource (330122): Annette Murray, BScPharm
- Anderson DJ, Podgorny K, Berrios-Torres SI, et al. Strategies to prevent surgical site infections in acute care hospitals: 2014 update. Infect Control Hosp Epidemiol 2014;35:605-27.
- CDC. National targets and metrics. December 2016. https://health.gov/hcq/prevent-hai-measures.asp. (Accessed December 13, 2016).
- Bratzler DW, Dellinger EP, Olsen KM, et al. Clinical practice guidelines for antimicrobial prophylaxis in surgery. Am J Health Syst Pharm 2013;70:195-283.
- Allegranzi B, Bischoff P, de Jonge S, et al. New WHO recommendations on preoperative measures for surgical site infection prevention: an evidence-based global perspective. Lancet Infect Dis 2016;16:e276-87.
- Allegranzi B, Zayed B, Bischoff P, et al. New WHO recommendations on intraoperative and postoperative measures for surgical site infection prevention: an evidence-based global perspective. Lancet Infect Dis 2016;16:e288-303.
- The Joint Commission. National Patient Safety Goals Effective January 2017. https://www.jointcommission.org/assets/1/6/2017_NPSG_HAP_ER.pdf. (Accessed December 16, 2016).
- Calfee DP. Editorial commentary: considering universal mupirocin decolonization as an option for preventing surgical site infections. Clin Infect Dis 2016;62:637-9.
Cite this document as follows: Clinical Resource, Preventing Surgical Site Infections. Pharmacist’s Letter/Prescriber’s Letter. January 2017.