Management of Surgical Site Infections
Endorsed by: POSNA, AANA, APTA, MIS, OTA
Use of Imaging
Limited evidence supports the use of medical imagining in the diagnostic evaluation of patients with a suspected organ/space (i.e. bone, joint, and implant) surgical site infection.
Strong evidence supports that synovial fluid and tissue cultures are strong rule-in tests for the diagnosis of infection; negative synovial fluid and tissue cultures do not reliably exclude infection.
Ten high quality studies were identified that addressed the role of culture in the diagnosis of surgical site infection; notably only two of the studies (Holinka, Puig-Verdie) included patients with infections involving orthopaedic sites other than hip or knee arthroplasties.
SYNOVIAL FLUID CULTURES
Three high quality studies (Gallo, Tomas, Spangehl) evaluated the yield of synovial fluid cultures in the diagnosis of prosthetic joint infection. Two of the studies found strong evidence to support fluid culture in the diagnosis of PJI (Tomas, Spangehl) while one found moderate evidence in support (Gallo).
INTRAOPERATIVE TISSUE CULTURES
Seven high quality studies evaluated the yield of intra-operative tissue cultures in the diagnosis of surgical site infection (Aggarwal, Holinka, Hughes, Panousis, Puig-Verdie, Spangehl, Trampuz). Of these, six of the seven studies revealed strong evidence in support of tissue culture to rule in the diagnosis of infection; one found the evidence to be moderate (Holinka). Additionally, the method by which the organism was grown was relevant. In these seven studies, there was variability in the performance of tissue culture in excluding infection. One high quality study evaluated the value of positive culture only from enrichment broth (Smith). Broth-only positive cultures showed poor correlation as a rule-in or rule-out test for infection. Two high-quality studies evaluated the performance of tissue cultures compared with swab cultures (Aggarwal, Spangehl). Both demonstrated better accuracy of tissue cultures over swab cultures.
NUMBER OF INTRAOPERATIVE CULTURES
Multiple tissue cultures should be collected to improve the accuracy of infection diagnosis. One moderate quality study (Atkins) quantified the number of samples needed to confirm the diagnosis of infection. A single positive culture for an organism of limited virulence was shown to have poor predictive value as a rule-in test. Two distinct positive cultures for the same organism provided strong evidence of periprosthetic infection.
DURATION OF CULTURE INCUBATION
One high quality (Schafer) and one moderate quality (Butler-Wu) study reviewed the duration of culture incubation for chronic periprosthetic infection. Both studies demonstrated improved yield when both aerobic and anaerobic cultures were incubated for 14 days.
PRIOR ANTIBIOTIC EXPOSURE
One high quality study evaluated the effect of prior antibiotic therapy on the yield of sonicate and tissue culture. The yield of culture was reduced when antibiotic therapy was administered within 14 days of culture collection.
Strong evidence supports that C-reactive Protein is a strong rule-in and rule-out marker for patients with suspected surgical site infections.
Multiple high-quality studies and meta-analysis of the study data support the use of C-reactive protein in the diagnosis of surgical site infection (Bottner et al 2007, Glehr et al 2013, Cipriano et al 2012, Jacovides et al 2011). Several moderate quality studies (Yi et al 2015, Piper et al 2009, 2010, Bedair et al 2011) also support its use. It was found to be both sensitive and specific in detecting periprosthetic infection and served as an accurate screening tool, with a positive or negative value demonstrating the likelihood of the presence or absence of infection. Studies vary with respect to the timing and thresholds used to diagnose infection. Both Yi et al 2015 and Bedair et al 2011 confirmed its utility during the early postoperative period. Despite this variation, it has proven its accuracy across investigations. While cutoff values at which an infection is diagnosed vary between studies, and based on time postoperatively it has been shown to be a superior screening test relative to other serological studies.
Erythrocyte Sedimentation Rate
Limited strength evidence does not support the use of ESR, alone, to rule in and rule out surgical site infections due to conflicting data.
Multiple high-quality studies (Bottner et al 2007, Cipriano et al 2012, Panousis et al 2005) have demonstrated moderate to weak ability of ESR as a solitary test to diagnose or exclude surgical site infection. It is felt to be too variable with respect to time from surgery and in the presence of other confounding factors (such as inflammatory arthropathy) to be considered an accurate tool in diagnosis alone but may be considered as a tool to be used in conjunction with other tests.
Clinical Exam for the Diagnosis of Surgical Site Infections
Moderate strength evidence supports that clinical exam (i.e. pain, drainage, fever) is a moderate to strong rule-in test (i.e. high probability of presence of infection, if test is positive) for patients with suspected surgical site infections, but a weak rule-out test.
Patients with suspected surgical site infections should be assessed by a history and physical examination. Specific data were available for a structured history, presence of fever, and persistent wound drainage. One study of moderate evidence by Pons 1999 used a structured interview to evaluate 80 patients undergoing revision total hip arthroplasty of whom 16 patients had proven infection by histology and microbiology culture. A positive clinical examination was the presence of one of the following: current painful joint, history of chronic joint pain; or a history of wound drainage or fever lasting greater than 48 hours in the first month after primary surgery. A positive history had a sensitivity of 0.625 and specificity of 0.98.
One moderate strength study by Bernard 2004 evaluated the presence of fever and persistent drainage against the confirmed infections of positive culture in 230 patients undergoing revision joint surgery. Fever had a sensitivity of 0.53 and specificity of 0.90, and persistent drainage had a sensitivity of 0.53 and specificity of 0.90.
Strong Evidence of Factors Associated with Increased Risk of SSI
Strong evidence supports that the following factors are associated with an increased risk of infection: • Anemia • Duration of Hospital Stay • Immunosuppressive Medications • History of Alcohol Abuse • Obesity • Depression • History of Congestive Heart Failure • Dementia • HIV/AIDS
There were eight high quality studies on the association of Anemia with the risk of SSI. Of these, five revealed an association between anemia and SSI. Four studies reviewed the risk of PJI and the 5th study reviewed the risk of infection and cervical spine fusion. Determinations were based on regression analyses of large data bases. Greenky et al 2012 identified the significant risk of anemia in PJI of development of SSI.
Duration of Hospital Stay
There were 11 high quality studies that examined the association between the length of hospital stay and the risk of SSI. Of these, seven revealed an association between increased length of stay and the risk of SSI. The studies were a range of multi-variant analysis and regression analysis. Three studies revealed that prolonged preoperative inpatient stays were related to increased risk of infection. Four studies revealed that prolonged post op hospitalization correlated with an increased risk of SSI. Longer hospital stays, including both pre-op and post-op stays correlated with increasing risk of SSI development.
Ten high quality studies were reviewed that looked at the effects of immunosuppressive agents. Of these, seven revealed a strong correlation between the use of immunosuppressive medications and an increased risk of SSI. These studies reviewed the effects of these medications on the risk of SSI associated with total joint replacement, spine surgery and ACL reconstruction. Momohara 2011 identified specifically that infliximab and etanercept combined with prolonged disease duration were associated with increased SSI risk. Giles 2006 identified increased risks of SSI associated with taking Tumor Necrosis Factor medications.
Five high quality articles were reviewed. Three revealed a strong correlation between alcohol abuse and the risk of SSI. The articles used multi-variant analysis and looked a range of orthopaedic procedures and the effect of alcohol abuse on the risk of SSI on these procedures. Large multivariate studies from Cavanaugh 2015, Grammatico 2015 and Jain 2015, surveying thousands of patients, consistently show increased risks associated with increased alcohol consumption.
Fourteen high quality studies showed a correlation between obesity and the risk of SSI. These studies used multivariant analysis showing that increasing BMI correlated strongly with the risk of post op infection. All of the studies showed significantly increased risk of SSI that correlate well with increased BMI. Several studies identified additional risks associated with increased BMI over 40. These risks include cardiac, pulmonary and systemic complications in additional to the increased SSI risks.
Four high quality studies confirmed a correlation between depression and the risk of SSI. All four studies used regression analysis. In each of the multivariate studies a correlation between clinically detected depression and increased risks of surgical site infection was identified.
Congestive Heart Failure
Two high quality studies revealed a strong correlation between the risk of CHF and SSI. These studies were all multi-variant regression analysis studies. Patients with CHF also have a higher risk of other vascular problems.
Two large high quality studies using regression analysis revealed a strong correlation between Dementia and the risk of SSI in geriatric fractures patients. Dementia is an independent risk factor for occurrence of a surgical site infection
Four high quality studies revealed a high correlation between the diagnosis of HIV/AIDs and the risks of SSI. There was a strong correlation between the diagnosis of HIV/AIDs and the risk of infection. Boylan revealed an increased risk of SSI of 17%.
Increased Associated Risk of SSI
Moderate strength evidence supports that patients meeting one or more of the following criteria are at an increased risk of infection after hip and knee arthroplasty: • Chronic Kidney Disease • Diabetes (conflicting evidence) • Tobacco Use/Smoking (conflicting evidence) • Malnutrition (conflicting evidence)
Chronic Kidney Disease
The risk of SSI in patients with chronic kidney disease (CKD) correlates positively with the severity of renal disease. Five high quality studies revealed using multivariate analysis and to identify the increased risk of SSI in patients with CKD. The severity of CKD and the description of dialysis and transplant patients were not identifiable within the studies.
26 high quality studies were reviewed. 13 of the studies showed a correlation between diabetes and the risk of SSI. 13 studies showed no correlation between diabetes and the risk of SSI. The strength of the recommendation was classified as “moderate” due to the divergence between the study findings. The impact of quality diabetic control could not be determined on the outcomes of the studies.
22 high quality studies were reviewed. 9 studies showed an association between tobacco use and increased risk of SSI. 12 studies showed no statistically significant differences between smokers and nonsmokers regarding associated risk of SSI. Many of the studies do not define the amount of tobacco
used, description of current versus former smokers, or the length of time for use of tobacco. While tobacco use is widely accepted as a risk factor for increasing the risk of SSI, of 22 HQ studies, 9 confirmed the correlation and 12 failed to confirm the correlation, and one showed a negative association with smoking and risk of SSI. This may be due to the definition of magnitude, effect size, heterogeneity of populations between studies.
Malnutrition is a known risk factor for patients undergoing surgical procedures. Patients with malnutrition can suffer from a range of poor outcomes including increased risk of death, sepsis and poor wound healing. Six high quality articles were reviewed. Of these, three articles identified a correlation with increased risk of SSI. Bohl et al 2016 identified significantly increased risks of SSI associated with hypoalbuminemia. Grammatico et al 2015 also showed higher risks of SSI due to malnutrition.
Limited Evidence of Increased Associated SSI Risk
Limited strength evidence supports that patients meeting one or more of the following criteria are at an increased risk of infection after hip and knee arthroplasty: • Cancer • Hypertension (conflicting evidence) • Liver Disease (conflicting evidence)
Antibiotic Duration for Management of Surgical Site Infections
Moderate evidence supports that, in the setting of retained total joint arthroplasty, antibiotic protocols of 8 weeks do not result in significantly different outcomes when compared to protocols of 3 to 6-month duration.
The optimal duration of antibiotic therapy is not known. There was one high quality study (Lora-Tamayo 2016) and two low quality (Puhto 2012, Siqueira 2015) studies that evaluated short term antibiotics vs long term antibiotics in the setting of infected total joint arthroplasties. Both studies showed no significant difference in resolution of infection according to treatment duration.
In the absence of reliable evidence, it is the opinion of the work group that adjunctive treatment is of limited value in the management of surgical site infections.
1. There is consensus opinion that local delivery of antibiotics could be beneficial in the management of surgical site infections.
Rifampin Use for Management of Surgical Site Infections
Moderate evidence supports that rifampin, as a second antimicrobial, increases the probability of treatment success for staphylococcal infections in the setting of retained orthopaedic implants.
Very few high quality studies were identified regarding the optimal antibiotic treatment regarding specific microbes. One high quality study (Zimmerli 1998) and one low-quality studies (El Helou 2010) addressed the addition of Rifampin and its effect on infection resolution in the setting of debridement and implant retention.
Surgical Timing and Percutaneous Drainage
In the absence of reliable evidence, it is the opinion of the work group that the definitive strategy to successfully treat surgical site infections is thorough debridement.
In the absence of reliable evidence, it is the opinion of the work group that irrigation and debridement are the cornerstones of successful management of surgical site infections and timely management is crucial, especially in the setting of orthopaedic implants.
Timing and Implant Removal
In the absence of reliable evidence, it is the opinion of the work group that implants should be removed if clinically safe and feasible due to the development of biofilm creating a barrier to successful treatment.
Regarding the role of implant removal associated with SSI, there is a paucity of research and evidence regarding the optimal implant management. The decision to retain or remove implants based on the clinical situation balancing morbity of removal with clearance of infection. While implant retention may be necessary in many cases, it is the recommendation of this committee that implants should be removed if clinically appropriate and feasible due to the development of biofilm as a barrier to successful treatment.
Guideline Work Group:
- Douglas Lundy, MD, Co-Chair
- Alexander McLaren, MD, Co-Chair
- Peter F. Sturm, MD
- Sudheer Reddy, MD
- Gregory S. Stacy, MD
- Gwo-Chin Lee, MD
- Hrayr Basmajian, MD
- Thomas Fleeter, MD
- Andrew Schoenfeld, MD
- Paul Anderson, MD
- Sandra B. Nelson, MD
- Joseph Hsu, MD
- Kim Chillag, MD
Carter Cassidy, MD
- William O. Shaffer, MD - AAOS Medical Director
- Deborah S. Cummins, PhD
- Jayson N. Murray, MA - Director, Clinical Quality & Value
- Mary DeMars - Coordinator, Clinical Quality & Value
- Mukarram Mohiuddin, MPH - Lead Research Analyst, Clinical Quality & Value
- Danielle Schulte, MS - Manager, Clinical Quality & Value
- Peter Shores, MPH - Statistician, Clinical Quality & Value
- Kaitlyn Sevarino, MBA - Senior Manager, Clinical Quality & Value
AAOS Clinical Practice Guidelines Section Leader:
Gregory Brown, MD, PhD
AAOS Committee on Evidence-Based Quality and Value Chair:
Kevin Shea, MD
AAOS Council on Research and Quality Chair:
Robert H. Quinn, MD
Additional Contributing Members:
- Douglas Osmon, MD
- Eric Hume, MD
- Robert Brophy, MD