Faculty Bibliography

BACKGROUND:Microbiologic cultures, the current gold standard diagnostic method for invasive Candida infections, have low specificity and take up to 2-5 days to grow. We present the results of the first extensive multicenter clinical trial of a new nanodiagnostic approach, T2 magnetic resonance (T2MR), for diagnosis of candidemia. METHODS:Blood specimens were collected from 1801 hospitalized patients who had a blood culture ordered for routine standard of care; 250 of them were manually supplemented with concentrations from <1 to 100 colony-forming units (CFUs)/mL for 5 different Candida species. RESULTS:T2MR demonstrated an overall specificity per assay of 99.4% (95% confidence interval [CI], 99.1%-99.6%) with a mean time to negative result of 4.2 ± 0.9 hours. Subanalysis yielded a specificity of 98.9% (95% CI, 98.3%-99.4%) for Candida albicans/Candida tropicalis, 99.3% (95% CI, 98.7%-99.6%) for Candida parapsilosis, and 99.9% (95% CI, 99.7%-100.0%) for Candida krusei/Candida glabrata. The overall sensitivity was found to be 91.1% (95% CI, 86.9%-94.2%) with a mean time of 4.4 ± 1.0 hours for detection and species identification. The subgroup analysis showed a sensitivity of 92.3% (95% CI, 85.4%-96.6%) for C. albicans/C. tropicalis, 94.2% (95% CI, 84.1%-98.8%) for C. parapsilosis, and 88.1% (95% CI, 80.2%-93.7%) for C. krusei/C. glabrata. The limit of detection was 1 CFU/mL for C. tropicalis and C. krusei, 2 CFU/mL for C. albicans and C. glabrata, and 3 CFU/mL for C. parapsilosis. The negative predictive value was estimated to range from 99.5% to 99.0% in a study population with 5% and 10% prevalence of candidemia, respectively. CONCLUSIONS:T2MR is the first fully automated technology that directly analyzes whole blood specimens to identify species without the need for prior isolation of Candida species, and represents a breakthrough shift into a new era of molecular diagnostics. CLINICAL TRIALS REGISTRATION/BACKGROUND:NCT01752166.

BACKGROUND:The impact of Clostridium difficile colonization in C. difficile infection (CDI) is inadequately explored. As a result, asymptomatic carriage is not considered in the development of infection control policies and the burden of carrier state in long-term care facilities (LTCFs) is unknown. PURPOSE/OBJECTIVE:To explore the epidemiology of C. difficile colonization in LTCFs, identify predisposing factors and describe its impact on healthcare management. DATA SOURCES/METHODS:PubMed, Embase and Web of Science (up to June 2014) without language restriction, complemented by reference lists of eligible studies. STUDY SELECTION/METHODS:All studies providing extractable data on the prevalence of toxigenic C. difficile colonization among asymptomatic residents in LTCFs. DATA EXTRACTION/METHODS:Two authors extracted data independently. STATISTICAL METHODS/METHODS:The pooled colonization estimates were calculated using the double arcsine methodology and reported along with their 95% random-effects confidence intervals (CIs), using DerSimonian-Laird weights. We assessed the impact of patient-level covariates on the risk of colonization and effects were reported as odds ratios (OR, 95% CI). We used the colonization estimates to simulate the effective reproduction number R through a Monte Carlo technique. RESULTS:Based on data from 9 eligible studies that met the specified criteria and included 1,371 subjects, we found that 14.8% (95%CI 7.6%-24.0%) of LTCF residents are asymptomatic carriers of toxigenic C. difficile. Colonization estimates were significantly higher in facilities with prior CDI outbreak (30.1% vs. 6.5%, p = 0.01). Patient history of CDI (OR 6.07; 95% CI 2.06-17.88; effect derived from 3 studies), prior hospitalization (OR 2.11; 95% CI 1.08-4.13; derived from 3 studies) and antimicrobial use within previous 3 months (OR 3.68; 95% CI 2.04-6.62; derived from 4 studies) were associated with colonization. The predicted colonization rate at admission was 8.9%. CONCLUSION/CONCLUSIONS:Asymptomatic carriage of toxigenic C. difficile represents a significant burden in LTCFs and is associated with prior CDI outbreaks in the facility, a history of CDI, prior hospitalization and antimicrobial use. These findings can impact infection control measures at LTCFs.

OBJECTIVES/OBJECTIVE:It has been suggested that colonization with C. difficile protects from infection. Nevertheless, the association between carriage of toxinogenic strains and ensuing C. difficile infections (CDIs) has not been studied. METHODS:We searched PubMed and EMBASE databases up to 20 June 2014, using the term "difficile". Our primary outcomes of interest included the prevalence of isolation of toxinogenic C. difficile or its toxins from asymptomatic patients on hospital admission through stool or rectal swab testing and the risk of ensuing infection among colonized and noncolonized patients. Data on previous hospitalization, antibiotic, and proton pump inhibitor (PPI) use and prior CDIs among colonized and noncolonized patients were also extracted. RESULTS:Nineteen out of 26,081 studies on 8,725 patients were included. The pooled prevalence of toxinogenic C. difficile colonization was 8.1% (95% confidence interval (CI) 5.7-11.1%), with an increasing trend over time (P=0.003), and 10.0% (95% CI 7.1-13.4%) among North American studies. Patients colonized upon hospital admission had a 5.9 times higher risk of subsequent CDIs compared with noncolonized patients (relative risk (RR) 5.86; 95% CI 4.21-8.16). The risk of CDI for colonized patients was 21.8% (95% CI 7.9-40.1%), which was significantly higher than that of noncolonized patients (3.4%; 95% CI 1.5-6.0%; P=0.03), with an attributable risk of 18.4%. History of hospitalization during the previous 3 months was associated with a higher risk of colonization (RR 1.63; 95% CI 1.13-2.34), as opposed to previous antibiotic (RR 1.07; 95% CI 0.75-1.53) and PPI use (RR 1.44; 95% CI 0.94-2.23), as well as history of CDI (RR 1.45; 95% CI 0.66-3.18) that had no impact. CONCLUSIONS:Over 8% of admitted patients are carriers of toxinogenic C. difficile with an almost 6 times higher risk of infection. These findings update current knowledge regarding the contribution of colonization in CDI epidemiology and stress the importance of preventive measures toward colonized patients.

Several factors including antibiotic use, immunosuppression and frequent hospitalizations make solid organ transplant (SOT) recipients vulnerable to Clostridium difficile infection (CDI). We conducted a meta-analysis of published studies from 1991-2014 to estimate the prevalence of CDI in this patient population. We searched PubMed, EMBASE and Google Scholar databases. Among the 75,940 retrieved citations, we found 30 studies coded from 35 articles that were relevant to our study. Based on these studies, we estimated the prevalence of CDI among 21,683 patients who underwent transplantation of kidney, liver, lungs, heart, pancreas, intestine or more than one organ and stratified each study based on the type of transplanted organ, place of the study conduction, and size of patient population. The overall estimated prevalence in SOT recipients was 7.4% [95%CI, (5.6-9.5%)] and it varied based on the type of organ transplant. The prevalence was 12.7% [95%CI, (6.4%-20.9%)] among patients who underwent transplantation for more than one organ. The prevalence among other SOT recipients was: lung 10.8% [95% CI, (5.5%-17.7%)], liver 9.1 % [95%CI, (5.8%-13.2%)], intestine 8% [95% CI, (2.6%-15.9%)], heart 5.2% [95%CI, (1.8%-10.2%)], kidney 4.7% [95% CI, (2.6%-7.3%)], and pancreas 3.2% [95% CI, (0.5%-7.9%)]. Among the studies that reported relevant data, the estimated prevalence of severe CDI was 5.3% [95% CI (2.3%-9.3%)] and the overall recurrence rate was 19.7% [95% CI, (13.7%-26.6%)]. In summary, CDI is a significant complication after SOT and preventive strategies are important in order to reduce the CDI related morbidity and mortality.

Clinical guidelines play a central role in day-to-day practice. We assessed the degree of incorporation of cost analyses to guidelines and identified modifiable characteristics that could affect the level of incorporation.We selected the 100 most cited guidelines listed on the National Guideline Clearinghouse (http://www.guideline.gov) and determined the number of guidelines that used cost analyses in their reasoning and the overall percentage of incorporation of relevant cost analyses available in PubMed. Differences between medical specialties were also studied. Then, we performed a case-control study using incorporated and not incorporated cost analyses after 1:1 matching by study subject and compared them by the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) statement requirements and other criteria.We found that 57% of guidelines do not use any cost justification. Guidelines incorporate a weighted average of 6.0% (95% confidence interval [CI] 4.3-7.9) among 3396 available cost analyses, with cardiology and infectious diseases guidelines incorporating 10.8% (95% CI 5.3-18.1) and 9.9% (95% CI 3.9- 18.2), respectively, and hematology/oncology and urology guidelines incorporating 4.5% (95% CI 1.6-8.6) and 1.6% (95% CI 0.4-3.5), respectively. Based on the CHEERS requirements, the mean number of items reported by the 148 incorporated cost analyses was 18.6 (SD = 3.7), a small but significant difference over controls (17.8 items; P = 0.02). Included analyses were also more likely to directly relate cost reductions to healthcare outcomes (92.6% vs 81.1%, P = 0.004) and declare the funding source (72.3% vs 53.4%, P < 0.001), while similar number of cases and controls reported a noncommercial funding source (71% vs 72.7%; P = 0.8).Guidelines remain an underused mechanism for the cost-effective allocation of available resources and a minority of practice guidelines incorporates cost analyses utilizing only 6% of the available cost analyses. Fulfilling the CHEERS requirements, directly relating costs with healthcare outcomes and transparently declaring the funding source seem to be valued by guideline-writing committees.

The burden of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE) colonization among the increasing number of solid organ transplant patients has not been systematically explored. We searched PubMed and EMBASE for pertinent articles, performed a meta-analysis of prevalence across eligible studies and estimated the risk of ensuing MRSA or VRE infections relative to colonization status. We stratified effects in the pretransplant and posttransplant period. Twenty-three studies were considered eligible. Seventeen out of 23 (74%) referred to liver transplants. Before transplantation, the pooled prevalence estimate for MRSA and VRE was 8.5% (95% confidence interval [CI] 3.2–15.8) and 11.9% (95% CI 6.8–18.2), respectively. MRSA estimate was influenced by small studies and was lower (4.0%; 95% CI 0.4–10.2) across large studies (>200 patients). After transplantation, the prevalence estimates were 9.4% (95% CI 3.0–18.5) for MRSA and 16.2% (95% CI 10.7–22.6) for VRE. Pretransplant as well as posttransplant MRSA colonization significantly increased the risk for MRSA infections (pooled risk ratio [RR] 5.51; 95% CI 2.36–12.90 and RR 10.56; 95% CI 5.58–19.95, respectively). Pretransplant and posttransplant VRE colonization were also associated with significant risk of VRE infection (RR 6.65; 95% CI 2.54–17.41 and RR 7.93; 95% CI 2.36–26.67, respectively). Solid organ transplantation is a high-risk setting for MRSA and VRE colonization, and carrier state is associated with infection. Upgraded focus in prevention and eradication strategies is warranted.