Michael J. Durkin

Seasonal Variation of Common Surgical Site Infections: Does Season Matter?

OBJECTIVE To evaluate seasonal variation in the rate of surgical site infections (SSI) following commonly performed surgical procedures. DESIGN Retrospective cohort study. METHODS We analyzed 6 years (January 1, 2007, through December 31, 2012) of data from the 15 most commonly performed procedures in 20 hospitals in the Duke Infection Control Outreach Network. We defined summer as July through September. First, we performed 3 separate Poisson regression analyses (unadjusted, multivariable, and polynomial) to estimate prevalence rates and prevalence rate ratios of SSI following procedures performed in summer versus nonsummer months. Then, we stratified our results to obtain estimates based on procedure type and organism type. Finally, we performed a sensitivity analysis to test the robustness of our findings. RESULTS We identified 4,543 SSI following 441,428 surgical procedures (overall prevalence rate, 1.03/100 procedures). The rate of SSI was significantly higher during the summer compared with the remainder of the year (1.11/100 procedures vs 1.00/100 procedures; prevalence rate ratio, 1.11 [95% CI, 1.04-1.19]; P=.002). Stratum-specific SSI calculations revealed higher SSI rates during the summer for both spinal (P=.03) and nonspinal (P=.004) procedures and revealed higher rates during the summer for SSI due to either gram-positive cocci (P=.006) or gram-negative bacilli (P=.004). Multivariable regression analysis and sensitivity analyses confirmed our findings. CONCLUSIONS The rate of SSI following commonly performed surgical procedures was higher during the summer compared with the remainder of the year. Summer SSI rates remained elevated after stratification by organism and spinal versus nonspinal surgery, and rates did not change after controlling for other known SSI risk factors.

Postoperative infection in spine surgery: does the month matter?

OBJECT The relationship between time of year and surgical site infection (SSI) following neurosurgical procedures is poorly understood. Authors of previous reports have demonstrated that rates of SSI following neurosurgical procedures performed during the summer months were higher compared with rates during other seasons. It is unclear, however, if this difference was related to climatological changes or inexperienced medical trainees (the July effect). The aim of this study was to evaluate for seasonal variation of SSI following spine surgery in a network of nonteaching community hospitals. METHODS The authors analyzed 6 years of prospectively collected surveillance data (January 1, 2007, to December 31, 2012) from all laminectomies and spinal fusions from 20 hospitals in the Duke Infection Control Outreach Network of community hospitals. Surgical site infections were defined using National Healthcare Safety Network criteria and identified using standardized methods across study hospitals. Regression models were then constructed using Poisson distribution to evaluate for seasonal trends by month. Each analysis was first performed for all SSIs and then for SSIs caused by specific organisms or classes of organisms. Categorical analysis was performed using two separate definitions of summer: June through September (definition 1), and July through September (definition 2). The prevalence rate of SSIs during the summer was compared with the prevalence rate during the remainder of the year by calculating prevalence rate ratios and 95% confidence intervals. RESULTS The authors identified 642 SSIs following 57,559 neurosurgical procedures (overall prevalence rate = 1.11/100 procedures); 215 occurred following 24,466 laminectomies (prevalence rate = 0.88/100 procedures), and 427 following 33,093 spinal fusions (prevalence rate = 1.29/100 procedures). Common causes of SSI were Staphylococcus aureus (n = 380; 59%), coagulase-negative staphylococci (n = 90; 14%), and Escherichia coli (n = 41; 6.4%). Poisson regression models demonstrated increases in the rates of SSI during each of the summer months for all SSIs and SSIs due to gram-positive cocci, S. aureus, and methicillin-sensitive S. aureus. Categorical analysis confirmed that the rate of SSI during the 4-month summer period was higher than the rate during the remainder of the year, regardless of which definition for summer was used (definition 1, p = 0.008; definition 2, p = 0.003). Similarly, the rates of SSI due to grampositive cocci and S. aureus were higher during the summer months than the remainder of the year regardless of which definition of summer was used. However, the rate of SSI due to gram-negative bacilli was not. CONCLUSIONS The rate of SSI following fusion or spinal laminectomy/laminoplasty was higher during the summer in this network of community hospitals. The increase appears to be related to increases in SSIs caused by gram-positive cocci and, more specifically, S. aureus. Given the nonteaching nature of these hospitals, the findings demonstrate that increases in the rate of SSI during the summer are more likely related to ecological and/or environmental factors than the July effect.

Surveying the Surveillance: Surgical Site Infections Excluded by the January 2013 Updated Surveillance Definitions

The updated 2013 Centers for Disease Control and Prevention/National Healthcare Safety Network definitions for surgical site infections (SSIs) reduced the duration of prolonged surveillance from 1 year to 90 days and defined which procedure types require prolonged surveillance. Applying the updated 2013 SSI definitions to cases analyzed using the pre-2013 surveillance definitions excluded 10% of previously identified SSIs.

A Comparison Between National Healthcare Safety Network Laboratory-Identified Event Reporting versus Traditional Surveillance for Clostridium difficile Infection

OBJECTIVE Hospitals in the National Healthcare Safety Network began reporting laboratory-identified (LabID) Clostridium difficile infection (CDI) events in January 2013. Our study quantified the differences between the LabID and traditional surveillance methods. DESIGN Cohort study. SETTING A cohort of 29 community hospitals in the southeastern United States. METHODS A period of 6 months (January 1, 2013, to June 30, 2013) of prospectively collected data using both LabID and traditional surveillance definitions were analyzed. CDI events with mismatched surveillance categories between LabID and traditional definitions were identified and characterized further. Hospital-onset CDI (HO-CDI) rates for the entire cohort of hospitals were calculated using each method, then hospital-specific HO-CDI rates and standardized infection ratios (SIRs) were calculated. Hospital rankings based on each CDI surveillance measure were compared. RESULTS A total of 1,252 incident LabID CDI events were identified during 708,551 patient-days; 286 (23%) mismatched CDI events were detected. The overall HO-CDI rate was 6.0 vs 4.4 per 10,000 patient-days for LabID and traditional surveillance, respectively (P<.001); of 29 hospitals, 25 (86%) detected a higher CDI rate using LabID compared with the traditional method. Hospital rank in the cohort differed greatly between surveillance measures. A rank change of at least 5 places occurred in 9 of 28 hospitals (32%) between LabID and traditional CDI surveillance methods, and for SIR. CONCLUSIONS LabID surveillance resulted in a higher hospital-onset CDI incidence rate than did traditional surveillance. Hospital-specific rankings varied based on the HO-CDI surveillance measure used. A clear understanding of differences in CDI surveillance measures is important when interpreting national and local CDI data.

Antifungal catheter lock therapy for the management of a persistent Candida albicans bloodstream infection in an adult receiving hemodialysis.

Antifungal catheter lock therapy (AfLT) with liposomal amphotericin B has been used in the treatment of pediatric central line infections caused by Candida species; however, reports describing the use of liposomal amphotericin B lock therapy in the adult hemodialysis patient population are lacking. Management of central line–associated candidemia with systemic therapy alone is often challenging due to the propensity of Candida species to form biofilms on foreign bodies. We describe a 64‐year‐old woman who was receiving hemodialysis 3 times/week and was hospitalized with persistent fungemia. Despite receiving intravenous micafungin, she had multiple positive blood cultures for Candida albicans, which finally cleared after 7 days. Her double‐lumen catheter was considered the most likely nidus of infection. Although catheter removal would have been preferred, this was not possible given her vasculopathy, history of multiple bloodstream infections, and lack of other available sites for vascular access. Catheter exchange was performed, and liposomal amphotericin B AfLT was administered in combination with intravenous micafungin for a total of 6 days. During this time, the patient experienced no discernible adverse effects secondary to AfLT. At discharge, AfLT was discontinued, and intravenous micafungin was changed to oral fluconazole. After 6 months of treatment, the patient remained culture negative and maintained her dialysis access. To our knowledge, this is the first case report of liposomal amphotericin B catheter lock therapy used to manage a persistent C. albicans bloodstream infection in an adult receiving hemodialysis. AfLT is a novel concept for treating catheter‐associated fungal infections. Liposomal amphotericin B was chosen based on its favorable in vitro activity against Candida species biofilms in catheter lock environments. We identified several barriers to implementing AfLT, and these issues may prohibit the use of AfLT. This case report illustrates the benefits and challenges of managing catheter‐associated fungal infections with AfLT. Further study is required to examine the efficacy, safety, and feasibility of this approach.

Epidemiology of Surgical Site Infection in a Community Hospital Network

OBJECTIVE To describe the epidemiology of complex surgical site infection (SSI) following commonly performed surgical procedures in community hospitals and to characterize trends of SSI prevalence rates over time for MRSA and other common pathogens METHODS We prospectively collected SSI data at 29 community hospitals in the southeastern United States from 2008 through 2012. We determined the overall prevalence rates of SSI for commonly performed procedures during this 5-year study period. For each year of the study, we then calculated prevalence rates of SSI stratified by causative organism. We created log-binomial regression models to analyze trends of SSI prevalence over time for all pathogens combined and specifically for MRSA. RESULTS A total of 3,988 complex SSIs occurred following 532,694 procedures (prevalence rate, 0.7 infections per 100 procedures). SSIs occurred most frequently after small bowel surgery, peripheral vascular bypass surgery, and colon surgery. Staphylococcus aureus was the most common pathogen. The prevalence rate of SSI decreased from 0.76 infections per 100 procedures in 2008 to 0.69 infections per 100 procedures in 2012 (prevalence rate ratio [PRR], 0.90; 95% confidence interval [CI], 0.82-1.00). A more substantial decrease in MRSA SSI (PRR, 0.69; 95% CI, 0.54-0.89) was largely responsible for this overall trend. CONCLUSIONS The prevalence of MRSA SSI decreased from 2008 to 2012 in our network of community hospitals. This decrease in MRSA SSI prevalence led to an overall decrease in SSI prevalence over the study period.

An Automated Surveillance Strategy to Identify Infectious Complications After Cardiac Implantable Electronic Device Procedures.

Background.  The optimum approach for infectious complication surveillance for cardiac implantable electronic device (CIED) procedures is unclear. We created an automated surveillance tool for infectious complications after CIED procedures. Methods.  Adults having CIED procedures between January 1, 2005 and December 31, 2011 at Duke University Hospital were identified retrospectively using International Classification of Diseases, 9th revision (ICD-9) procedure codes. Potential infections were identified with combinations of ICD-9 diagnosis codes and microbiology data for 365 days postprocedure. All microbiology-identified and a subset of ICD-9 code-identified possible cases, as well as a subset of procedures without microbiology or ICD-9 codes, were reviewed. Test performance characteristics for specific queries were calculated. Results.  Overall, 6097 patients had 7137 procedures. Of these, 1686 procedures with potential infectious complications were identified: 174 by both ICD-9 code and microbiology, 14 only by microbiology, and 1498 only by ICD-9 criteria. We reviewed 558 potential cases, including all 188 microbiology-identified cases, 250 randomly selected ICD-9 cases, and 120 with neither. Overall, 65 unique infections were identified, including 5 of 250 reviewed cases identified only by ICD-9 codes. Queries that included microbiology data and ICD-9 code 996.61 had good overall test performance, with sensitivities of approximately 90% and specificities of approximately 80%. Queries with ICD-9 codes alone had poor specificity. Extrapolation of reviewed infectious rates to nonreviewed cases yields an estimated rate of infection of 1.3%. Conclusions.  Electronic queries with combinations of ICD-9 codes and microbiologic data can be created and have good test performance characteristics for identifying likely infectious complications of CIED procedures.

A Descriptive Study of the Risk Factors Associated With Catheter-Related Bloodstream Infections in the Home Parenteral Nutrition Population:

BACKGROUND Home parenteral nutrition (HPN) is increasingly used for nutrition support after patients are discharged from the hospital. Catheter-related bloodstream infections (CR-BSI) are a common and potentially fatal complication of HPN. The risk factors for development of CR-BSI in the outpatient setting are poorly understood. METHODS We conducted an observational, retrospective study of 225 patients discharged from Barnes-Jewish Hospital on HPN between January 1, 2007, and December 31, 2009. HPN complications were defined as any cause that led to either premature discontinuation of HPN therapy or catheter replacement. CR-BSI events were identified by provider documentation. We calculated the overall complication rate and the complication rate specifically due to CR-BSI. Backward stepwise Cox regression analyses were used to assess for independent predictors of catheter-related complications. RESULTS In total, 111 of 225 patients (49%) developed complications while receiving HPN (incidence = 5.06 episodes/1000 catheter days). Sixty-eight of 225 patients (30%) required catheter removal for CR-BSI (incidence = 3.10 episodes/1000 catheter days). Independent predictors of line removal specifically due to infection included anticoagulant use, ulcer or open wound, and Medicare or Medicaid insurance. The following risk factors were associated with catheter-associated complications and/or CR-BSI: the presence of ulcers, the use of systemic anticoagulants, public insurance (Medicare or Medicaid), and patient age. Independent predictors of line removal for any complication included age and anticoagulant use. CONCLUSION Catheter-related complications were extremely common in patients receiving HPN. Healthcare providers caring for individuals who require HPN should be aware of risk factors for complications.

The potential impact of excluding funguria from the surveillance definition of catheter-associated urinary tract infection.

Funguria rarely represents true infection in the urinary tract. Excluding yeast from the catheter-associated urinary tract infection (CAUTI) surveillance definition reduced CAUTI rates by nearly 25% in community hospitals and at an academic, tertiary-care medical center.

Prevention and Management of Central Line-Associated Bloodstream Infections in Hospital Practice

Abstract In this article aimed at hospitalists, we examine the literature on preventive measures for central line–associated bloodstream infections (CLABSIs) and optimal management once a CLABSI has been established. We focus on a number of core preventive measures and the contemporary approach of bundling these measures for maximal impact in reducing infection rates. We then discuss empiric and pathogen-specific antibiotic therapy, including the role of newer antimicrobial agents, as well as the management of an infected central venous catheter.