An integrated single-cell RNA-seq map of human neuroblastoma tumors and preclinical models uncovers divergent mesenchymal-like gene expression programs

Neuroblastoma is a common pediatric cancer, where preclinical studies suggest that a mesenchymal-like gene expression program contributes to chemotherapy resistance. However, clinical outcomes remain poor, implying we need a better understanding of the relationship between patient tumor heterogeneity and preclinical models. Here, we generated single-cell RNA-seq maps of neuroblastoma cell lines, patient-derived xenograft models (PDX), and a genetically engineered mouse model (GEMM). We developed an unsupervised machine learning approach ('automatic consensus nonnegative matrix factorization' (acNMF)) to compare the gene expression programs found in preclinical models to a large cohort of patient tumors. We confirmed a weakly expressed, mesenchymal-like program in otherwise adrenergic cancer cells in some pre-treated high-risk patient tumors, but this appears distinct from the presumptive drug-resistance mesenchymal programs evident in cell lines. Surprisingly however, this weak-mesenchymal-like program was maintained in PDX and could be chemotherapy-induced in our GEMM after only 24 hours, suggesting an uncharacterized therapy-escape mechanism. Collectively, our findings improve the understanding of how neuroblastoma patient tumor heterogeneity is reflected in preclinical models, provides a comprehensive integrated resource, and a generalizable set of computational methodologies for the joint analysis of clinical and pre-clinical single-cell RNA-seq datasets.

The importance of pharmacist engagement in diagnostic stewardship

Diagnostic stewardship is increasingly recognized as a powerful tool to improve patient safety. Given the close relationship between diagnostic testing and antimicrobial misuse, antimicrobial stewardship (AMS) pharmacists should be key members of the diagnostic team. Pharmacists practicing in AMS already frequently engage with clinicians to improve the diagnostic process and have many skills needed for the implementation of diagnostic stewardship initiatives. As diagnostic stewardship becomes more broadly used, all infectious disease clinicians, including pharmacists, must collaborate to optimize patient care.

Antibiotic Myths for the Infectious Diseases Clinician

Antimicrobials are commonly prescribed and often misunderstood. With more than 50% of hospitalized patients receiving an antimicrobial agent at any point in time, judicious and optimal use of these drugs is paramount to advancing patient care. This narrative will focus on myths relevant to nuanced consultation from infectious diseases specialists, particularly surrounding specific considerations for a variety of antibiotics.

Utility of triazole antifungal therapeutic drug monitoring: Insights from the Society of Infectious Diseases Pharmacists: Endorsed by the Mycoses Study Group Education and Research Consortium

Triazole antifungals (i.e., fluconazole, itraconazole, voriconazole, posaconazole, and isavuconazole) are commonly used in clinical practice to prevent or treat invasive fungal infections. Most triazole antifungals require therapeutic drug monitoring (TDM) due to highly variable pharmacokinetics, known drug interactions, and established relationships between exposure and response. On behalf of the Society of Infectious Diseases Pharmacists (SIDP), this insight describes the pharmacokinetic principles and pharmacodynamic targets of commonly used triazole antifungals and provides the rationale for utility of TDM within each agent.

C5a-licensed phagocytes drive sterilizing immunity during systemic fungal infection

Systemic candidiasis is a common, high-mortality, nosocomial fungal infection. Unexpectedly, it has emerged as a complication of anti-complement C5-targeted monoclonal antibody treatment, indicating a critical niche for C5 in antifungal immunity. We identified transcription of complement system genes as the top biological pathway induced in candidemic patients and as predictive of candidemia. Mechanistically, C5a-C5aR1 promoted fungal clearance and host survival in a mouse model of systemic candidiasis by stimulating phagocyte effector function and ERK- and AKT-dependent survival in infected tissues. C5ar1 ablation rewired macrophage metabolism downstream of mTOR, promoting their apoptosis and enhancing mortality through kidney injury. Besides hepatocyte-derived C5, local C5 produced intrinsically by phagocytes provided a key substrate for antifungal protection. Lower serum C5a concentrations or a C5 polymorphism that decreases leukocyte C5 expression correlated independently with poor patient outcomes. Thus, local, phagocyte-derived C5 production licenses phagocyte antimicrobial function and confers innate protection during systemic fungal infection.

Leveraging diagnostic stewardship within antimicrobial stewardship programmes

Novel diagnostic stewardship in infectious disease consists of interventions that modify ordering, processing, and reporting of diagnostic tests to provide the right test for the right patient, prompting the right action. The interventions work upstream and synergistically with traditional antimicrobial stewardship efforts. As diagnostic stewardship continues to gain public attention, it is critical that antimicrobial stewardship programmes not only learn how to effectively leverage diagnostic testing to improve antimicrobial use but also ensure that they are stakeholders and leaders in developing new diagnostic stewardship interventions within their institutions. This review will discuss the need for diagnostic and antimicrobial stewardship, the interplay of diagnostic and antimicrobial stewardship, evidence of benefit to antimicrobial stewardship programmes, and considerations for successfully engaging in diagnostic stewardship interventions. This article is part of the Antibiotic stewardship Special Issue: https://www.drugsincontext.com/special_issues/antimicrobial-stewardship-a-focus-on-the-need-for-moderation.

2019. Understanding the Impact of COVID-19 Pandemic on Central Line-Associated Bloodstream Infections (CLABSIs): Expanding Analysis to the Microbiologic Level

Background

Increases in central line-associated bloodstream infection (CLABSI) rates have been reported in association with the COVID-19 pandemic, particularly among Candida species and coagulase-negative Staphylococcal species (CoNS). We sought to further validate the impact of the COVID-19 pandemic on CLABSI trends and perform a microbiologic analysis.

Methods

This is an IRB-approved retrospective analysis of CLABSIs across a network of 38 community hospitals in southeastern United States. CLABSI rates were compared between pre-pandemic (1/1/2018-3/30/2020) and pandemic periods (4/1/2020-12/31/2021). Regression models were developed to evaluate CLABSI incidence over time. Likelihood ratio tests were used to compare models that were exclusively time-dependent to segmented regression models that also accounted for the COVID-19 pandemic.

Results

A total of 1,167 CLABSIs over 1,345,062 central line days were analyzed (Table 1). The mean monthly CLABSI rate per hospital increased from 0.63 to 1.01 per 1,000 central line days (p< 0.001) in the pandemic period (Table 1). CLABSIs secondary to Candida (0.16 to 0.33, p< 0.001), CoNS (0.09 to 0.22, p< 0.001), and Enterococcal species (0.06 to 0.18, p=0.001) increased, while Escherichia coli CLABSIs decreased (0.04 to 0.01, p< 0.001). Upon regression modeling, the COVID-19 pandemic was associated with increases in monthly CLABSI rates by Candida and Enterococcus species (Figure 1). In contrast, the changes in CoNS and Escherichia coli CLABSI rates were better explained by exclusively time-dependent models (Figure 1; Table 2). Non-sustained changes in Staphylococcus aureus and Klebsiella pneumoniae CLABSI rates were also noted (Table 2). Table 1:Count data, central line days, and mean monthly CLABSI incidence by organism per hospital.

Rates are provided as CLABSIs per 1,000 central line days. Figure 1:Regression analysis of monthly CLABSI rates by pathogen.

Gray areas denote COVID-19 pandemic period. Statistically significant level changes in CLABSI rates were observed among Candida and Enterococcus spp. (RR=1.92, CI 1.16-3.20 and 2.42, CI 1.09-5.38). Staphylococcus aureus CLABSI rates had a non-sustained but significant increase at the onset of COVID-19 (RR 2.20, CI 1.16-4.20). CoNS and E. coli rate changes occurred independent of COVID-19 (see Table 2). Table 2:Coefficient table of regression analyses for CLABSI rates by pathogen.

Exclusively time-dependent models were compared to segmented regression models for each organism and, if no significant difference was noted between models, only the time-dependent model was applied.

Conclusion

The COVID-19 pandemic was associated with substantial increases in CLABSIs, driven in part by Candida and Enterococcus species across this network of hospitals. However, the observed increase in CoNS CLABSIs and decrease in Escherichia coli CLABSIs appear to have occurred independently of COVID-19, which only became apparent upon regression analysis. Interpretation of pre-post statistics without assessment of pre-existing trends should be done cautiously. Additional analyses may help elucidate other factors influencing these CLABSI trends by organism.

Disclosures

Sonali D. Advani, MBBS, MPH, FIDSA, Locus Biosciences: Advisor/Consultant|Locus Biosciences: Honoraria|Sysmex America: Advisor/Consultant Melissa D. Johnson, PharmD, MHS, AAHIVP, Charles River Laboratories: Grant/Research Support|Entasis: Honoraria|Merck: Grant/Research Support|Pfizer: Honoraria|Scynexis: Grant/Research Support|Theratechnologies: Honoraria|UpToDate: Honoraria.

935. Antibiotic Use (AU) Adjustment by Infection-Related Patient Volume Across a Health System

Background

Benchmarking AU is important to identify opportunities and allocate resources within a health system. Patient level factors such as infection diagnosis codes further refine risk adjustments but have not been more widely adopted because of the burden of accurately collecting and submitting granular data. The goal of this study was to evaluate a novel metric to estimate facility-level infection burden as a potential factor to use in adjustment of AU.

Methods

We conducted a retrospective analysis of hospital administrative data (for calendar year 2020) from 8 hospitals in a single health system using a common electronic health record and coding department. We identified inpatient encounters with an infection-related primary ICD-10 code (I-PDX), based on the health system’s coding department determination and extracted the length of stay (LOS) for each encounter. For any encounter with an I-PDX, the entire LOS was classified as infection-related patient days (IPD). Overall AU in days of therapy (DOT) was adjusted using two novel infection diagnoses denominators. The first was based on proportion of total patient days (PD) attributable to I-PDX encounters (% I-PDX x PD). Since LOS tends to be longer in I-PDX, we also calculated DOT with adjustment for actual extracted IPDs. We then rank ordered study hospitals based on standard DOT / 1,000 PD, NHSN SAAR metrics, and our novel DOT / (% I-PDX x PD) and DOT / 1,000 IPD metrics.

Results

The proportion of I-PDX was highly variable among hospitals, with a system-wide median of 37.27% (range 23.48 - 43.32) (Figure 1). Using DOT / 1,000 patient days for 1 year, Hospital A was the lowest in the system and hospital H was the highest (Figure 2). However, after adjusting for the proportion of patients with I-PDX encounters and IPDs, hospital rank changed considerably, i.e. Hospital H and C respectively ranked lowest and Hospital A was highest.

Conclusion

These novel infection diagnoses PD denominators more closely associated facility level infection burden with AU, for a more refined rank order within the health system. These metrics provide an example of a parsimonious adjustment using patient level data that is already collected at any facility. Next steps might include indirect standardization using PDX categories and other patient level factors readily collected.

Disclosures

Melissa D. Johnson, PharmD, Charles River Laboratories: Grant/Research Support|Entasis: Honoraria|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Scynexis: Grant/Research Support|Theratechnologies: Grant/Research Support|UpToDate: Honoraria Rebekah W. Moehring, MD, MPH, FIDSA, FSHEA, UpToDate, Inc.: Author Royalties Angelina Davis, PharmD, M.S., Merck & Co.: Honoraria.

1570. Cumulative Antibiotic Exposure and Risk for Candidemia

Background

Broad-spectrum antibiotic use is a known risk factor for candidemia, but the duration and type of antibiotic exposure associated with greatest risk are not well characterized. Measurements of antibiotic days may be useful to assess cumulative burden of selective pressure on the microbiome and risk for candidemia.

Methods

This retrospective cohort study aimed to quantify the effect of antibiotic exposure on risk for candidemia. The primary outcome was hazard for developing candidemia across an array of antibiotic agents, classes and spectra. We measured antibiotic days of therapy (DOT) for adults admitted to Duke University hospitals 1/1/2016–12/31/2021. We excluded patients with community-onset candidemia, defined as growth of Candida spp. in blood culture collected ≤ 48 hours of admission, because antibiotic exposure prior to arrival was not reliably accessible. Time-to-event analyses were performed using the Nelson-Aalen estimator for modeling cumulative hazard functions to compare the proportion of candidemia observed based on exposure to each antibiotic. Logrank tests were used to evaluate for differences between hazard functions with a pre-specified alpha level of 0.05, and exponential cumulative proportional hazards models were implemented to generalize hazard functions.

Results

During 164,185 encounters in 105,330 unique patients, we identified candidemia in 237 patients. Prior to developing candidemia, cases received a total of 9,604 antibacterial DOT distributed across 46 unique antibiotic agents (Fig. 1) Carbapenems were associated with increased hazard for candidemia compared to beta-lactams (p< 0.005) (Figs. 2–3). There were 57 encounters for candidemia where meropenem was administered with a median of 10 DOT prior to onset of candidemia.

Days of Antibiotic Therapy by Agent and Outcome.

Conclusion

This work represents a novel approach to quantifying antibiotic exposure as a risk factor for candidemia. In an unadjusted model, we identified carbapenems as a high-risk class; additional analysis with adjusted regression models will help contextualize exposure risk with respect to comorbidity and illness severity. This work may serve as a reference for antibiotic stewards as they promote appropriate antibiotic use, including reducing overuse of broad-spectrum antibiotics.

Disclosures

Rebekah W. Moehring, MD, MPH, FIDSA, FSHEA, UpToDate, Inc.: Author Royalties Barbara D. Alexander, MD, Astellas: Advisor/Consultant|HealthtrackRx: Advisor/Consultant|HealthtrackRx: Grant/Research Support|Scynexis: Grant/Research Support|UpToDate: Advisor/Consultant Melissa D. Johnson, PharmD, Biomeme: Licensed Transcriptional Signature for Candidemia|Charles River Laboratories: Grant/Research Support|Entasis Therapeutics: Advisor/Consultant|Merck & Co. Inc: Advisor/Consultant|Merck & Co. Inc: Grant/Research Support|Pfizer, Inc.: Advisor/Consultant|Scynexis Inc.: Grant/Research Support|Theratechnologies: Advisor/Consultant.

1571. Hospital COVID-19 Burden Impact on Inpatient Antibiotic Use Rates

Background

COVID-19 shifted antibiotic stewardship program resources and changed antibiotic use (AU). Shifts in patient populations with COVID surges, including pauses to surgical procedures, and dynamic practice changes makes temporal associations difficult to interpret. Our analysis aimed to address the impact of COVID on AU after adjusting for other practice shifts.

Methods

We performed a longitudinal analysis of AU data from 30 Southeast US hospitals. Three pandemic phases (1: 3/20–6/20; 2: 7/20–10/20; 3: 11/20–2/21) were compared to baseline (1/2018–1/2020). AU (days of therapy (DOT)/1000 patient days (PD)) was collected for all antimicrobial agents and specific subgroups: broad spectrum (NHSN group for hospital-onset infections), CAP (ceftriaxone, azithromycin, levofloxacin, moxifloxacin, and doxycycline), and antifungal. Monthly COVID burden was defined as all PD attributed to a COVID admission. We fit negative binomial GEE models to AU including phase and interaction terms between COVID burden and phase to test the hypothesis that AU changes during the phases were related to COVID burden. Models included adjustment for Charlson comorbidity, surgical volume, time since 12/2017 and seasonality.

Results

Observed AU rates by subgroup varied over time; peaks were observed for different subgroups during distinct pandemic phases (Figure). Compared to baseline, we observed a significant increase in overall, broad spectrum, and CAP groups during phase 1 (Table). In phase 2, overall and CAP AU was significantly higher than baseline, but in phase 3, AU was similar to baseline. These phase changes were separate from effects of COVID burden, except in phase 1 where we observed significant effects on antifungal (increased) and CAP (decreased) AU (Table).

Conclusion

Changes in hospital AU observed during early phases of the COVID pandemic appeared unrelated to COVID burden and may have been due to indirect pandemic effects (e.g., case mix, healthcare resource shifts). By pandemic phase 3, these disruptive effects were not as apparent, potentially related to shifts in non-COVID patient populations or ASP resources, availability of COVID treatments, or increased learning, diagnostic certainty, and provider comfort with avoiding antibacterials in patients with suspected COVID over time.

Disclosures

Melissa D. Johnson, PharmD, Biomeme: Licensed Transcriptional Signature for Candidemia|Charles River Laboratories: Grant/Research Support|Entasis Therapeutics: Advisor/Consultant|Merck & Co. Inc: Advisor/Consultant|Merck & Co. Inc: Grant/Research Support|Pfizer, Inc.: Advisor/Consultant|Scynexis Inc.: Grant/Research Support|Theratechnologies: Advisor/Consultant Angelina Davis, PharmD, M.S., Merck & Co.: Honoraria Sonali D. Advani, MBBS, MPH, FIDSA, Locus Biosciences: Advisor/Consultant|Locus Biosciences: Honoraria|Sysmex America: Advisor/Consultant Ibukun Kalu, MD, Pfizer, Inc.: Institutional support for clinical trial Rebekah W. Moehring, MD, MPH, FIDSA, FSHEA, UpToDate, Inc.: Author Royalties.

955. Improving Pharmacist Access to Training in Antimicrobial Stewardship in Latin American Countries: Partnership between the Pharmaceutical Forum of the Americas (PFA) and the Society of Infectious Diseases Pharmacists (SIDP)

Background

Antimicrobial stewardship programs (AMS) in Latin America have varying degrees of development. One significant barrier is the lack of clinical pharmacists with specialized training in infectious diseases, as there are no residency programs or certifications available to train pharmacists in AMS in Latin America. To overcome this limitation and based on the roadmap for antimicrobial resistance action from the International Pharmaceutical Federation (FIP), the PFA established a partnership with SIDP to support specialized training and mentoring in AMS for pharmacists working in Latin America. Herein, we describe characteristics of this innovative program and its initial participants.

Methods

Pharmacist members of associations belonging to the PFA (9 Latin American countries) were invited to apply for the SIDP AMS Certificate Program (SIDP-CP) with additional mentoring. Selection was based on current employment status, support from hospital leadership, and an intermediate level of English. A 14-item survey was disseminated to the participants of this program and responses were collected in March 2022, at the beginning of their SIDP-CP. The survey collected information on demographics, characteristics of the AMS at their hospital, experience with AMS to-date, and support requirements to finish the SIDP-CP.

Results

The description of the SIDP-CP can be found in Figure 1. Surveys were completed by 11/12 (91.7%) program participants: 6 (54.5%) from Costa Rica, 4 (36.4%) from Colombia, and 1 (9.1%) from Argentina. Seven (63.6%) pharmacists work in hospitals with a formally approved AMS, with 6 providing basic and 1 reporting intermediate AMS services. None of the pharmacists have positions dedicated exclusively to AMS, and the majority of those surveyed work ≤ 25% of their time on AMS-related activities. In addition to completing the SIDP-CP, participants indicated high interest in attending periodic virtual meetings to increase their knowledge of how to implement, strengthen, or begin research in AMS.

Conclusion

Incorporating antimicrobial stewardship in all healthcare institutions worldwide is vital in the fight to slow antimicrobial resistance. Partnerships like this one between PFA and SIDP can inform future planning for expansion of AMS training.

Disclosures

José Pablo Díaz-Madriz, PharmD, MSc, Eli Lilly: Stocks/Bonds|Pfizer: Advisor/Consultant Melissa D. Johnson, PharmD, MHS, AAHIVP, Charles River Laboratories: Grant/Research Support|Entasis: Honoraria|Merck: Grant/Research Support|Pfizer: Honoraria|Scynexis: Grant/Research Support|Theratechnologies: Honoraria|UpToDate: Honoraria Scott J. Bergman, PharmD, BCIDP, FCCP, FIDSA, Merck & Co., Inc: Advisor/Consultant|Merck & Co., Inc: Grant/Research Support|Merck & Co., Inc: Honoraria|Pfizer: Advisor/Consultant|Pfizer: Honoraria.

Real World Effectiveness of Antifungal Prophylaxis with Posaconazole as the Primary Agent in Patients with Hematological Malignancies

Background and Objectives Patients undergoing induction/re-induction chemotherapy for hematologic malignancies (HM) are at risk for invasive fungal infections (IFIs). In 2015, Duke University Hospital (DUH) implemented a new standardized fungal prophylaxis protocol for adult patients undergoing induction chemotherapy for Acute Lymphocytic Leukemia, Acute Myelocytic Leukemia, and Myelodysplastic Syndrome. This study assessed the impact of protocol implementation on (1) use of antifungal prophylaxis, throughout the at-risk period and (2) patient outcomes such as IFI and mortality.

METHODS

Retrospective, observational study of adult HM patients admitted to DUH for induction/re-induction chemotherapy pre- (7/1/2013-12/31/2014) and post- (1/1/2015-10/31/2016) implementation of standardized antifungal prophylaxis protocol (which recommended posaconazole as the first-line agent). Patients were followed for up to 100 days after initiation of induction chemotherapy to evaluate use of antifungal prophylaxis and patient outcomes.

RESULTS

218 patients with hematologic malignancies were included (90 pre,128 post). Use of antifungal prophylaxis increased from 81.1% (pre) to 97.7% (post) (p<0.0001). Overall, 71% received posaconazole as initial antifungal prophylaxis (64.4% pre, 75.7% post). Approximately one-fourth of patients (25.6%, pre vs 26.6%, post) developed an IFI (proven/probable or possible using modified EORTC definitions) (p=0.868); 100-day mortality remained stable (18.9% pre vs 18.8% post, respectively p=0.979). Lack of antifungal prophylaxis and older age (≥60 years) were associated with higher risk of IFI.

CONCLUSION

Implementation of a standardized protocol with posaconazole as the primary agent was associated with increased use of antifungal prophylaxis among patients undergoing induction/re-induction chemotherapy for hematologic malignancies in our hospital. Lack of antifungal prophylaxis was an independent predictor of IFIs, underscoring the importance of prophylaxis in this at-risk population.

Top Myths of Diagnosis and Management of Infectious Diseases in Hospital Medicine

Antimicrobial agents are among the most frequently prescribed medications during hospitalization. However, approximately 30% to 50% or more of inpatient antimicrobial use is unnecessary or suboptimal. Herein, we describe 10 common myths of diagnosis and management that often occur in the hospital setting. Further, we discuss supporting data to dispel each of these myths. This analysis will provide hospitalists and other clinicians with a foundation for rational decision-making about antimicrobial use and support antimicrobial stewardship efforts at both the patient and institutional levels.

How to Harness the Power of Social Media for Quality Drug Information in Infectious Diseases: Perspectives on Behalf of the Society of Infectious Diseases Pharmacists

Clinicians, researchers, and the public frequently turn to digital channels and social media for up-to-the-minute information on novel therapeutics and vaccines. The value of credible infectious diseases drug information is more apparent in the setting of the coronavirus disease 2019 (COVID-19) pandemic. This viewpoint by the Society of Infectious Diseases Pharmacists (SIDP) provides guidance on utilizing social media platforms to optimize infectious diseases pharmacotherapy. It includes tips for all levels of users but primarily serves a guide for the infectious diseases clinician who has not yet joined social media. It compares various social media platforms and suggests which to begin with based on user needs, recommends efficient curation of social media content, and outlines a stepwise approach (shown below) to increasing engagement over time. This summary will hopefully spur further quality content and engagement regarding drug information from the infectious diseases social media network.

106. Pandemic Pinch: The Impact of COVID Response on Antimicrobial Stewardship Program (ASP) Resource Allocation

Background

The COVID-19 pandemic placed a strain on inpatient clinical and hospital programs due to increased patient volume and rapidly evolving data on best COVID-19 management strategies. However, the impact of the pandemic on ASPs has not been well described.

Methods

We performed a cross-sectional electronic survey of stewardship pharmacy and physician leaders in 37 hospitals within the Duke Antimicrobial Stewardship Outreach Network (DASON) (community) and Duke/UNC Health systems (academic) in April-May 2021. The survey included 60 questions related to staffing changes, use of COVID-targeted therapies, related restrictions, and medication shortages.

Results

Twenty-seven facilities responded (response rate of 73%). Pharmacy personnel was reduced in 17 (63%) facilities by an average of 16%. Impacted pharmacy personnel included the stewardship lead in 15/17 (88.2%) hospitals. Converting to remote work was rare and only reported in academic institutions (n=2, 7.4%). ASP personnel were reassigned to non-stewardship duties in 12 (44%) hospitals with only half returning to routine ASP work as of May 2021. Respondents estimated that 62% of routine ASP activities were diverted during the time of the pandemic. Non-traditional, pandemic-related ASP activities included managing multiple drug shortages, of which ventilator support medications (91%) were most common affecting patient care at 52% of facilities. Steroid and hydroxychloroquine shortages were less frequent (44% and 22%, respectively). Despite staff reductions, pharmacists often served as primary contact for remdesivir approvals either using a criteria-based checklist at dispensing or as part of a dedicated phone approval team (Figure). Most (77%) hospitals used a criteria-based pharmacist review strategy after remdesivir FDA approval. Restriction processes for other COVID-19 therapies such as tocilizumab, hydroxychloroquine, and ivermectin were reported in 64% of hospitals.

Remdesivir Allocation Strategy

Proportion of facilities implementing specific remdesivir allocation strategies from the time of the first US Food and Drug Administration (FDA) Emergency Use Authorization (EUA) through FDA approval

Conclusion

Pandemic response diverted routine ASP work and has not yet returned to baseline. Despite the reduction in pharmacy personnel due to the pandemic, the ASP pharmacy lead took on a novel and critical stewardship role throughout the pandemic exemplified by their involvement in novel treatment allocation for COVID patients.

Disclosures

Melissa D. Johnson, PharmD, MHS, Astellas (Consultant, Grant/Research Support)Charles River Laboratories (Grant/Research Support)Cidara (Consultant)Merck & Co (Consultant, Research Grant or Support)Paratek (Consultant)Pfizer (Consultant)Scynexis (Scientific Research Study Investigator)Theratechnologies (Consultant)UpToDate (Other Financial or Material Support, Author Royalties) Sonali D. Advani, MBBS, MPH, Nothing to disclose Rebekah W. Moehring, MD, MPH, UpToDate, Inc. (Other Financial or Material Support, Author Royalties)

Coronavirus Disease 2019-Associated Invasive Fungal Infection

Coronavirus disease 2019 (COVID-19) can become complicated by secondary invasive fungal infections (IFIs), stemming primarily from severe lung damage and immunologic deficits associated with the virus or immunomodulatory therapy. Other risk factors include poorly controlled diabetes, structural lung disease and/or other comorbidities, and fungal colonization. Opportunistic IFI following severe respiratory viral illness has been increasingly recognized, most notably with severe influenza. There have been many reports of fungal infections associated with COVID-19, initially predominated by pulmonary aspergillosis, but with recent emergence of mucormycosis, candidiasis, and endemic mycoses. These infections can be challenging to diagnose and are associated with poor outcomes. The reported incidence of IFI has varied, often related to heterogeneity in patient populations, surveillance protocols, and definitions used for classification of fungal infections. Herein, we review IFI complicating COVID-19 and address knowledge gaps related to epidemiology, diagnosis, and management of COVID-19-associated fungal infections.

Inflammatory Protein Profiles in Plasma of Candidaemia Patients and the Contribution of Host Genetics to Their Variability

Circulatory inflammatory proteins play a significant role in anti-Candida host immune defence. However, little is known about the genetic variation that contributes to the variability of inflammatory responses in response to C. albicans. To systematically characterize inflammatory responses in Candida infection, we profiled 91 circulatory inflammatory proteins in peripheral blood mononuclear cells (PBMCs) stimulated with C. albicans yeast isolated from 378 individuals of European origin from the 500 Functional Genomics (500FG) cohort of the Human Functional Genomics Project (HFGP) and Lifelines Deep cohort. To identify the genetic factors that determine variation in inflammatory protein responses, we correlated genome-wide single nucleotide polymorphism (SNP) genotypes with protein abundance (protein quantitative trait loci, pQTLs) produced by the Candida-stimulated PBMCs. Furthermore, we investigated whether differences in survival of candidaemia patients can be explained by modulating levels of inflammatory proteins. We identified five genome-wide significant pQTLs that modulate IL-8, MCP-2, MMP-1, and CCL3 in response to C. albicans. In addition, our genetic analysis suggested that GADD45G from rs10114707 locus that reached genome-wide significance could be a potential core gene that regulates a cytokine network upon Candida infection. Last but not least, we observed that a trans-pQTL marked from SNP rs7651677 at chromosome 3 that influences urokinase plasminogen activator (uPA) is strongly associated with patient survival (P_survival = 3.52 x 10^-5, OR 3). Overall, our genetic analysis showed that genetic variation determines the abundance of circulatory proteins in response to Candida infection.

The host transcriptional response to Candidemia is dominated by neutrophil activation and heme biosynthesis and supports novel diagnostic approaches

BACKGROUND

Candidemia is one of the most common nosocomial bloodstream infections in the United States, causing significant morbidity and mortality in hospitalized patients, but the breadth of the host response to Candida infections in human patients remains poorly defined.

METHODS

In order to better define the host response to Candida infection at the transcriptional level, we performed RNA sequencing on serial peripheral blood samples from 48 hospitalized patients with blood cultures positive for Candida species and compared them to patients with other acute viral, bacterial, and non-infectious illnesses. Regularized multinomial regression was utilized to develop pathogen class-specific gene expression classifiers.

RESULTS

Candidemia triggers a unique, robust, and conserved transcriptomic response in human hosts with 1641 genes differentially upregulated compared to healthy controls. Many of these genes corresponded to components of the immune response to fungal infection, heavily weighted toward neutrophil activation, heme biosynthesis, and T cell signaling. We developed pathogen class-specific classifiers from these unique signals capable of identifying and differentiating candidemia, viral, or bacterial infection across a variety of hosts with a high degree of accuracy (auROC 0.98 for candidemia, 0.99 for viral and bacterial infection). This classifier was validated on two separate human cohorts (auROC 0.88 for viral infection and 0.87 for bacterial infection in one cohort; auROC 0.97 in another cohort) and an in vitro model (auROC 0.94 for fungal infection, 0.96 for bacterial, and 0.90 for viral infection).

CONCLUSIONS

Transcriptional analysis of circulating leukocytes in patients with acute Candida infections defines novel aspects of the breadth of the human immune response during candidemia and suggests promising diagnostic approaches for simultaneously differentiating multiple types of clinical illnesses in at-risk, acutely ill patients.

Antifungals in Clinical Use and the Pipeline

Over the past 15 years, there has been an increase in the development and utilization of newer antifungal agents. The ideal antifungal, however, in regard to spectrum of activity, pharmacokinetic/pharmacodynamic properties, development of resistance, safety, and drug interaction profile remains elusive. This article reviews pharmacologic aspects of Food and Drug Administration-approved polyenes, flucytosine, azoles, and echinocandins as well as promising pipeline antifungal agents. Unique properties of these newer agents are highlighted. The clinical role of established and investigational antifungal agents as treatment and/or prevention of invasive fungal infections is discussed.

Effects of a Collaborative, Community Hospital Network for Antimicrobial Stewardship Program Implementation

BACKGROUND

Individual hospitals may lack expertise, data resources, and educational tools to support antimicrobial stewardship programs (ASP).

METHODS

We established a collaborative, consultative network focused on hospital ASP implementation. Services included on-site expert consultation, shared database for routine feedback and benchmarking, and educational programs. We performed a retrospective, longitudinal analysis of antimicrobial use (AU) in 17 hospitals that participated for at least 36 months during 2013-2018. ASP practice was assessed using structured interviews. Segmented regression estimated change in facility-wide AU after a 1-year assessment, planning, and intervention initiation period. Year one AU trend (1 to 12 months) and AU trend following the first year (13 to 42 months) were compared using relative rates (RR). Monthly AU rates were measured in days of therapy (DOT) per 1,000 patient days for overall AU, specific agents, and agent groups.

RESULTS

Analyzed data included over 2.5 million DOT and almost 3 million patient-days. Participating hospitals increased ASP-focused activities over time. Network-wide overall AU trends were flat during the first 12 months after network entry but decreased thereafter (RR month 42 vs month 13, 0.95, 95% Confidence Interval (CI) 0.91-0.99.) Large variation was seen in hospital-specific AU. Fluoroquinolone use was stable during year one, then dropped significantly. Other agent groups demonstrated a non-significant downward trajectory after year one.

CONCLUSIONS

Network hospitals increased ASP activities and demonstrated decline in AU over a 42-month period. A collaborative, consultative network is a unique model in which hospitals can access ASP implementation expertise to support long-term program growth.

Long-term risk of hepatocellular carcinoma mortality in 23220 hospitalized patients treated with micafungin or other parenteral antifungals

BACKGROUND

Liver tumours observed in rats exposed to micafungin led to a black box warning upon approval in Europe in 2008. Micafungin's risk for liver carcinogenicity in humans has not been investigated. We sought to describe the risk of fatal hepatocellular carcinoma (HCC) among persons who received micafungin and other parenteral antifungals (PAFs) with up to 12 years of follow-up.

METHODS

We assembled a US multicentre cohort of hospitalized patients who received micafungin or other PAFs between 2005 and 2012. We used propensity score (PS) matching on patient characteristics from electronic medical records to compare rates of HCC mortality identified through the National Death Index though to the end of December 2016. We computed HRs and 95% CIs.

RESULTS

A total of 40110 patients who received a PAF were identified; 6903 micafungin recipients (87% of those identified) were successfully matched to 16317 comparator PAF users. Ten incident HCC deaths, one in the micafungin-exposed group and nine among comparator PAF users, occurred in 71285 person-years of follow-up. The HCC mortality rate was 0.05 per 1000 person-years in micafungin patients and 0.17 per 1000 person-years in comparator PAF patients. The PS-matched HR for micafungin versus comparator PAF was 0.29 (95% CI 0.04-2.24).

CONCLUSIONS

Both micafungin and comparator PAFs were associated with HCC mortality rates of <0.2 per 1000 person-years. Given the very low event rates, any potential risk for HCC should not play a role in clinical decisions regarding treatment with micafungin or other PAFs investigated in this study.

Core Recommendations for Antifungal Stewardship: A Statement of the Mycoses Study Group Education and Research Consortium

In recent years, the global public health community has increasingly recognized the importance of antimicrobial stewardship (AMS) in the fight to improve outcomes, decrease costs, and curb increases in antimicrobial resistance around the world. However, the subject of antifungal stewardship (AFS) has received less attention. While the principles of AMS guidelines likely apply to stewarding of antifungal agents, there are additional considerations unique to AFS and the complex field of fungal infections that require specific recommendations. In this article, we review the literature on AMS best practices and discuss AFS through the lens of the global core elements of AMS. We offer recommendations for best practices in AFS based on a synthesis of this evidence by an interdisciplinary expert panel of members of the Mycoses Study Group Education and Research Consortium. We also discuss research directions in this rapidly evolving field. AFS is an emerging and important component of AMS, yet requires special considerations in certain areas such as expertise, education, interventions to optimize utilization, therapeutic drug monitoring, and data analysis and reporting.

Invasive Fungal Infection After Lung Transplantation: Epidemiology in the Setting of Antifungal Prophylaxis

BACKGROUND

Lung transplant recipients commonly develop invasive fungal infections (IFIs), but the most effective strategies to prevent IFIs following lung transplantation are not known.

METHODS

We prospectively collected clinical data on all patients who underwent lung transplantation at a tertiary care academic hospital from January 2007-October 2014. Standard antifungal prophylaxis consisted of aerosolized amphotericin B lipid complex during the transplant hospitalization. For the first 180 days after transplant, we analyzed prevalence rates and timing of IFIs, risk factors for IFIs, and data from IFIs that broke through prophylaxis.

RESULTS

In total, 156 of 815 lung transplant recipients developed IFIs (prevalence rate, 19.1 IFIs per 100 surgeries, 95% confidence interval [CI] 16.4-21.8%). The prevalence rate of invasive candidiasis (IC) was 11.4% (95% CI 9.2-13.6%), and the rate of non-Candida IFIs was 8.8% (95% CI 6.9-10.8%). First episodes of IC occurred a median of 31 days (interquartile range [IQR] 16-56 days) after transplant, while non-Candida IFIs occurred later, at a median of 86 days (IQR 40-121 days) after transplant. Of 169 IFI episodes, 121 (72%) occurred in the absence of recent antifungal prophylaxis; however, IC and non-Candida breakthrough IFIs were observed, most often representing failures of micafungin (n = 16) and aerosolized amphotericin B (n = 24) prophylaxis, respectively.

CONCLUSIONS

Lung transplant recipients at our hospital had high rates of IFIs, despite receiving prophylaxis with aerosolized amphotericin B lipid complex during the transplant hospitalization. These data suggest benefit in providing systemic antifungal prophylaxis targeting Candida for up to 90 days after transplant and extending mold-active prophylaxis for up to 180 days after surgery.

Bilateral Basal Ganglia Hemorrhage in a Patient with Confirmed COVID-19

Bilateral basal ganglia hemorrhage is exceedingly rare. To our knowledge, our patient is the first reported case of a confirmed coronavirus disease 2019 (COVID-19) patient who had bilateral basal ganglia hemorrhage. In the absence of other risk factors for bilateral deep cerebral involvement, we suspect that COVID-19 may be contributing to these rare pathologies. Most published data represent a correlation between COVID-19 and neurologic complications, and more research is still needed to prove causation.

A Genome-Wide Functional Genomics Approach Identifies Susceptibility Pathways to Fungal Bloodstream Infection in Humans

BACKGROUND

Candidemia, one of the most common causes of fungal bloodstream infection, leads to mortality rates up to 40% in affected patients. Understanding genetic mechanisms for differential susceptibility to candidemia may aid in designing host-directed therapies.

METHODS

We performed the first genome-wide association study on candidemia, and we integrated these data with variants that affect cytokines in different cellular systems stimulated with Candida albicans.

RESULTS

We observed strong association between candidemia and a variant, rs8028958, that significantly affects the expression levels of PLA2G4B in blood. We found that up to 35% of the susceptibility loci affect in vitro cytokine production in response to Candida. Furthermore, potential causal genes located within these loci are enriched for lipid and arachidonic acid metabolism. Using an independent cohort, we also showed that the numbers of risk alleles at these loci are negatively correlated with reactive oxygen species and interleukin-6 levels in response to Candida. Finally, there was a significant correlation between susceptibility and allelic scores based on 16 independent candidemia-associated single-nucleotide polymorphisms that affect monocyte-derived cytokines, but not with T cell-derived cytokines.

CONCLUSIONS

Our results prioritize the disturbed lipid homeostasis and oxidative stress as potential mechanisms that affect monocyte-derived cytokines to influence susceptibility to candidemia.

Transcriptomic approaches elucidate novel aspects of the host immune response to candidemia

Objective

Examination of the human transcriptome in circulating leukocytes during invasive candidiasis can provide an innovative approach to defining immunologic mechanisms driving the host response to this deadly infection.

Methods

RNA sequencing was performed on peripheral blood samples from 50 hospitalized patients with blood culture positive invasive candidiasis, along with 30 control subjects. Generalized linear hypothesis testing and weighted gene co-expression network analysis (WGCNA) were used to define biological networks contributing to the host response to Candida infection.

Results

1,748 genes were differentially upregulated and 2,149 genes downregulated in the presence of candidemia compared to matched controls. These genes reflected many canonical antifungal immune response pathways including phagocytosis, neutrophil activation, type I interferon responses, and T cell signaling. However, the data also demonstrated activation of some less well described antifungal immune mechanisms, including B cell activation, upregulation of humoral immune response pathways, and a profound alteration in the host regulation of heme synthesis and iron metabolism. While iron is known to be critical for fungal pathogens such as Candida in vitro, this analysis offers evidence that the human host manipulates this system as a part of the overall response to fungal infection.

Conclusion

Analysis of the transcriptome in circulating white blood cells of infected human subjects offers unique and novel insight into the complex immunologic response to invasive candidiasis.

Real-world implications of QT prolongation in patients receiving voriconazole and amiodarone

Objectives

Voriconazole, a triazole antifungal, is frequently prescribed in a complex patient population with comorbidities that require concomitant administration of QT interval-prolonging medications. We sought to evaluate QT interval prolongation in patients receiving concomitant therapy with voriconazole and amiodarone and to assess the development of any potentially fatal cardiac arrhythmias as a result.

Methods

We conducted a retrospective observational study of patients who had received amiodarone and voriconazole concomitantly between 2005 and 2015, with a prior period of monotherapy, who had ECG data during monotherapy (baseline) and concomitant therapy (follow-up).

Results

We included 46 patients in our final analysis. Overall, the mean change in QT corrected (QTc) from baseline to follow-up was 49.0 ms (P < 0.001). Eighteen (39.1%) patients had a follow-up QTc interval ≥500 ms, with 17 (37.0%) having a change in QTc interval ≥60 ms from baseline to follow-up. Men were more likely to have a follow-up QTc interval of ≥500 ms. In multivariate analysis, only low serum potassium concentration and concomitant 'possible' QT-prolonging drugs were associated with a follow-up QTc interval ≥500 ms and a lower baseline QTc interval was associated with a change in QTc interval of ≥60 ms. Discharge diagnoses of cardiac arrhythmias and events were assessed and none was found to be related to concomitant therapy.

Conclusions

Concomitant therapy with amiodarone and voriconazole significantly prolonged the QTc interval to a degree greater than that on monotherapy. However, no clinically significant cardiac events were observed.

2089. Effect of the Duke Antimicrobial Stewardship Outreach Network (DASON): A Multi-Center Time Series Analysis

Background

DASON is a 30-member, community hospital network in the southeastern United States that supports the development and growth of local antibiotic stewardship programs (ASPs). Collaborative activities include on-site visits from liaison clinical pharmacists, data sharing for routine feedback and benchmarking, and educational programs.

Methods

We performed a retrospective cohort analysis of antibiotic use (AU) in 17 hospitals that participated in DASON for a minimum of 42 months during 2013–2018. Segmented negative binomial regression models were used to estimate the change in facility-wide AU after an initial 1-year assessment, planning, and ASP intervention initiation period. Baseline AU trend (1 to 12 months) was compared against AU following the first year (13 to 42 months). Monthly AU rates were measured in days of therapy (DOT) per 1,000 patient-days (pd). Models assessed overall AU and specific antibiotic groups, as defined by the National Healthcare Safety Network AU option. The models controlled for hospital size, presence of a pre-existing formal ASP upon network entry, and year of network entry.

Results

Hospital data included a total of 2,988,930 pd over 5 years. Facility-wide AU was increasing during the first year of network entry and then began decreasing by 0.2% per month (P = 0.01, figure). Fluoroquinolone use was stagnant in year one and then decreased by 1.5% per month (P ≤ 0.001, figure). Antifungal agents were decreasing in year one and continued to decrease 0.7% per month thereafter (P = 0.03, figure). Agents predominantly used for resistant Gram-positive infections and broad-spectrum agents used for hospital-onset infections were increasing during year one and then attenuated afterward, though the slope change did not reach statistical significance. The presence of a pre-existing formal ASP was not a significant covariate in any model, while bed size and year of network entry significantly contributed to models of some antibiotic groups.

Conclusion

Participation in DASON was associated with a decline in total AU and fluoroquinolone use, and a trend toward attenuated use of other broad-spectrum agents in community hospitals. Collaborative network experiences can help local ASPs achieve reductions in AU.

Disclosures

All authors: No reported disclosures.

1013. Electronic Assessment of Empiric Antibiotic Prescribing Using Diagnosis Codes

Background

Antimicrobial stewardship programs (ASPs) must understand empiric choices for specific disease syndromes to assess adherence to local empiric treatment guidelines. Electronically-derived metrics to track empiric therapy choices would allow ASPs to target areas for intervention without significant data collection burden.

Methods

Admissions from 10 community hospitals between 7/2016 and December 2018 were reviewed to identify those with common infectious syndromes: pneumonia (PNA), urinary tract infection (UTI) and skin and soft-tissue infection (SSTI). Admissions with a syndrome of interest were identified using AHRQ clinical classifications software codes based on ICD-10 codes for infection at the time of discharge. Admissions were categorized as having the syndrome of interest with or without sepsis. Antibiotics received during the first 48 hours of inpatient admission were obtained from electronic medication administration records. The proportion of syndrome admissions receiving specific antibiotic agents was determined to evaluate initial treatment choices as compared with local empiric guidelines. Antibiotic categories were not mutually exclusive, admissions receiving combination therapy were included in the count for each individual agent as well as the combination group. The denominator was the count of admissions with the syndrome of interest. Distributions were tracked over time to observe the effects of ASP intervention.

Results

The analysis included 49,303 admissions. The most common diagnosis was UTI (30%) followed by PNA (23%). Empiric antibiotic use varied by syndrome (Figure 1). In general, patients with a targeted infectious diagnosis and sepsis received more broad-spectrum agents than those without sepsis. SSTI was an exception, but few patients admitted with SSTI did not also have presumed sepsis. Longitudinal analysis demonstrated shifts from less preferred agents to guideline-concordant choices. For example, for admissions with a diagnosis of PNA, we observed a steady year on year increase in ceftriaxone (preferred) while levofloxacin (avoided in local guidelines) declined. (Figure 2)

Conclusion

Syndrome-specific diagnosis codes were helpful in assessing empiric antibiotic selection and may assist ASPs in improving empiric guideline adherence.

Disclosures

All authors: No reported disclosures.

2112. Voriconazole for Primary Prophylaxis: A Decade of Trends and Outcomes

Background

Invasive fungal infections (IFI) continue to affect the immunocompromised patient population. Many of these patients require antifungal prophylaxis. Voriconazole is an azole antifungal that has been utilized for preventing IFIs but does not have an approved indication for prophylaxis.

Methods

Adult patients admitted to Duke University Hospital from January 1, 2005 to December 31, 2015 who had received at least 2 days of systemic voriconazole as primary prophylaxis were included in this retrospective medical records review. Demographics, underlying comorbidities, adverse events, drug interactions, voriconazole blood concentrations, and microbiological data were assessed.

Results

Our review identified 403 patients receiving voriconazole for primary prophylaxis. 220 (55.6%) were male, 303 (75.2%) were Caucasian, and the mean age was 46.0 ± 15.7 years. 233 (57.8%) had leukemia, and 63 (15.6%) had lymphoma. 301 (74.7%) underwent hematopoietic transplant (BMT), and 45 (11.2%) had a solid-organ transplant. 176 (43.7%) patients received chemotherapy and 261 (64.8%) received immunosuppressive drugs. The mean voriconazole total daily maintenance dose was 416.1 ± 65.9 mg (5.5 ± 1.6 mg/kg/day). Patients received inpatient voriconazole for a mean of 19.5 ± 16.5 days. 371 (92.1%) patients received a concomitant interacting drug. Only 140 (43.7%) patients had therapeutic drug monitoring. The mean first voriconazole serum concentration was 1.8 ± 1.7 mg/L. 87 (21.6%) patients discontinued voriconazole prematurely; 41 (10.2% overall) of these patients had an adverse event requiring discontinuation. 5 had breakthrough fungal infections with microbiological data identifying a fungal species, which included Rhizopus spp. among others.

Conclusion

Voriconazole is frequently used for primary prophylaxis of IFIs and most commonly in BMT. It appears to be relatively well tolerated with some adverse side-effects (~10%) despite many potential drug–drug interactions and provides appropriate fungal coverage for many immunosuppressed patients. However, few patients had breakthrough fungal infections while receiving voriconazole. In a real-world setting, voriconazole can provide antifungal prevention in certain high-risk patients.

Disclosures

All authors: No reported disclosures.

996. Impact of Penicillin Allergy Labels on Carbapenem Use in a Multi-Center Study

Background

Antibiotic allergy labels lead to excess exposure to broad-spectrum antibiotics and can result in patient harm. We aimed to describe the prevalence of penicillin allergy labels (PAL) across a variety of hospital settings and its association with carbapenem exposure.

Methods

We performed a retrospective cohort analysis of inpatient admissions from 14 hospitals in the Duke Antimicrobial Stewardship Outreach Network (DASON) and Duke Health System from 2016 to 2018. Data were collected from the DASON central database which is derived from electronic health record extracts. PAL was defined from drug allergy documentation indicating any reaction to penicillin or its related agents, but did not include labels for other β-lactam agents (e.g., cephalosporin). Carbapenem exposure was defined as a binary variable indicating receipt of at least one dose of meropenem, ertapenem, doripenem or imipenem on an inpatient unit. The association between PAL and carbapenem exposure was assessed using multivariable logistical regression with candidate covariates including age, gender, comorbidity score, and exposure to intensive care or hematology/oncology unit. Hospital-level PAL prevalence was defined as the percentage of inpatient admissions. Hospital-level carbapenem use rates were assessed as days of therapy (DOT) per 1000 patient-days and stratified by PAL to understand the portion of use associated with PAL.

Results

Of the 727,168 admissions included in this study, 84,033 (11.6%) patients had a PAL. The majority of admissions with documented PAL were in patients >65 years old (47.9%, n = 40,240) and female (57.8%, n = 418,472). PAL was associated with a 2-fold higher risk of receipt of carbapenem (adjusted odds ratio 2.13, 95% CI 0.89–2.40, P < 0.0001). PAL prevalence varied among hospitals (median 14%, range 5–20%). Hospitals with antibiotic allergy-focused stewardship programs (ASP) had a similar PAL prevalence (median 13.8 vs. 15.9%, P = 0.08), but the percent of carbapenem DOT used in patients with PAL was similar (median 23% vs. 24%, P = 0.6).

Conclusion

PAL was associated with increased carbapenem exposure on the patient level. Allergy-focused ASP activities may affect PAL but it is unclear whether it reduces carbapenem use based on these observational data.

Disclosures

All authors: No reported disclosures.

2885. A Host Transcriptional Signature for Accurate Diagnosis of Candidemia in the Hospital Setting

Background

Candidemia is one of the most common nosocomial bloodstream infections in the United States and causes significant morbidity and mortality in hospitalized patients. Improved rapid diagnostics capable of differentiating candidemia from other causes of febrile illness in the hospitalized patient are of paramount importance. Pathogen class-specific biomarker-based diagnostics such as those focusing on host gene expression patterns in circulating leukocytes may offer a promising alternative.

Methods

RNA sequencing was performed on peripheral blood samples from 27 hospitalized patients with blood culture positive invasive candidiasis. Samples from healthy controls as well as at-risk subjects with acute febrile illness and similar clinical backgrounds but other infectious or noninfectious etiologies were used as comparator phenotypes (35 subjects with culture-proven bacterial infection, 49 with confirmed viral infection, and 17 with acute noninfectious illness). Bayesian techniques were utilized to develop infection-specific classifiers and leave one out cross-validation was used to estimate the predictive probability of each pathogen class.

Results

Candidemia triggers a unique, robust and conserved transcriptomic response in human hosts with 1,170 genes differentially upregulated compared with healthy controls. Based on this strength of signal, we developed a transcriptomic classifier that was capable of identifying candidemia, viral, or bacterial infection with a high degree of accuracy (auROC for Candida 0.93, Bacterial 0.98, Viral 0.99). The Candida component of this classifier (29-genes) was able to diagnose candidemia with a sensitivity of 88% and specificity of 100%.

Conclusion

The host transcriptomic response during candidemia in hospitalized adults is highly conserved and unique from the genomic responses to acute viral and bacterial infection. This approach shows promise for the development of host response-based classifiers capable of differentiating multiple types of clinical illnesses at once in at-risk febrile patients.

Disclosures

Ephraim L. Tsalik, MD MHS PhD, Immunexpress: Consultant; Predigen, Inc.: Officer or Board Member, Research Grant.

2087. Electronic Capture and Feedback of Standardized Antibiotic Clinical Indications Data Among Community Hospitals

Background

Antibiotic clinical indications allow stewardship programs to assess therapy appropriateness; however, many hospitals that require antibiotic indications upon order entry lack standardized mapping of indications leading to variability in entered values. Electronic capture and feedback of standardized antibiotic clinical indications data may allow hospitals to more effectively compare indication-specific prescribing trends among facilities.

Methods

We collected antibiotic indications from electronic medication orders for 6 DASON hospitals. These indications were mapped to a list of 15 standardized indication categories created by consensus of the DASON stewardship team. To demonstrate the feasibility and utility of standardized clinical indications mapping, we evaluated agents given for the indication C. difficile infection (CDI) in 2018. Differences between the hospitals were compared with highlight the added benefit of standardized indication data in evaluating antibiotic use and adoption of local guidelines.

Results

For 249,916 antibiotic days of therapy (DOT) with an indication available, a total of 125 unique indications were reported. Of note, 3 facilities allowed more than one indication to be entered at prescriber discretion. The distribution of antibiotic DOT mapped to the standardized indication list can be seen in Figure 1. The most common indication was the other category (19.5%). These were primarily other, no additional information (47%) or empiric therapy for an unknown source of infection (17%). Additional indications in the other category included chronic obstructive pulmonary disease exacerbations and sexually transmitted infections (< 5% each). Figure 2 depicts the agents used for CDI indication between facilities. Despite universal adoption of local guidelines where oral vancomycin is the drug of choice for treating CDI, there was variability seen in vancomycin CDI DOT (range: 60 – 80% of CDI DOT).

Conclusion

Stewardship programs can implement standardized antimicrobial indications to facilitate electronic capture, feedback, and comparison and efficiently identify stewardship targets. Additionally, hospitals may use these data to explore the appropriateness of antibiotic use.

Disclosures

All authors: No reported disclosures.

1044. Impact of Interdisciplinary Rounds on Antimicrobial Use at a Community Hospital

Background

Antimicrobial stewardship (AS) implementation is challenging in resource-limited settings such as smaller community hospitals that may lack dedicated personnel resources or have limited access to infectious diseases experts with dedicated time for AS. Few studies have evaluated the impact of interdisciplinary rounds as a strategy to optimize antimicrobial use (AU) in the community hospital setting.

Methods

We evaluated the impact of interdisciplinary rounds in a 280-bed acute care nonteaching, community hospital with an established ASP. The primary outcome was facility-wide antibiotic utilization pre- and post-implementation. Rounds included key healthcare personnel (hospitalists, clinical pharmacists, case managers, nurses) reviewing all patients on inpatient wards Monday through Friday, with a discussion of diagnosis, antibiotic selection, dosing, duration, and anticipated discharge plans. AU was compared for a 7-month post-intervention period (June 1, 2018–December 31, 2018) vs. similar months in 2017 based on days of therapy (DOT)/1,000 patient-days and length of therapy (LOT) per antimicrobial use admission. In addition, trends in AU for the post-intervention period were compared with the previous 17 months (January 1, 2017–May 31, 2018) using segmented binomial regression.

Results

Interdisciplinary rounds incorporating AS principles was associated with a decrease in overall AU in this facility, with a significant decrease of 16.33% (P < 0.0001) in DOT/1,000 pd in the first month and was stable (decrease of 1.1% per month, P = 0.15) thereafter (Figure 1). There was no significant change in LOT/admission after the first month of the intervention, but the trend demonstrated a 2% per month decrease (P < 0.03) thereafter (Figure 2). Comparing 2018 intervention months with similar months of 2017, the use of antibacterial agents decreased on average by 191.3 (95% CI −128.2 to −254.4) DOT/1,000 patient-days (Figure 3) and 0.546 (95% CI: −0.28 to −0.81) days per admission (Figure 4).

Conclusion

In this community hospital with an existing antimicrobial stewardship program, implementation of interdisciplinary rounds was associated with a substantial decrease in antimicrobial use. This was sustained for at least a 7-month period.

Disclosures

All authors: No reported disclosures.

Functional characterization of the G162R and D216H genetic variants of human CYP17A1

Cytochrome P450 17A1 (CYP17A1) is a dual-function enzyme catalyzing reactions necessary for cortisol and androgen biosynthesis. CYP17A1 is a validated drug target for prostate cancer as CYP17A1 inhibition significantly reduces circulating androgens and improves survival in castration-resistant prostate cancer. Germline CYP17A1 genetic variants with altered CYP17A1 activity manifesting as various endocrinopathies are extremely rare; however, characterizing these variants provides critical insights into CYP17A1 protein structure and function. By querying the dbSNP online database and publically available data from the 1000 genomes project (http://browser.1000genomes.org), we identified two CYP17A1 nonsynonymous genetic variants with unknown consequences for enzymatic activity and stability. We hypothesized that the resultant amino acid changes would alter CYP17A1 stability or activity. To test this hypothesis, we utilized a HEK-293T cell-based expression system to characterize the functional consequences of two CYP17A1 variants, D216H (rs200063521) and G162R (rs141821705). Cells transiently expressing the D216H variant demonstrate a selective impairment of 16α-hydroxyprogesterone synthesis by 2.1-fold compared to wild-type (WT) CYP17A1, while no effect on 17α-hydroxyprogesterone synthesis was observed. These data suggest that substrate orientations in the active site might be altered with this amino acid substitution. In contrast, the G162R substitution exhibits decreased CYP17A1 protein stability compared to WT with a near 70% reduction in protein levels as determined by immunoblot analysis. This variant is preferentially ubiquitinated and degraded prematurely, with an enzyme half-life calculated to be ∼2.5 h, and proteasome inhibitor treatment recovers G162R protein expression to WT levels. Together, these data provide new insights into CYP17A1 structure-function and stability mechanisms.

Cardiovascular Disease and HIV: Pathophysiology, Treatment Considerations, and Nursing Implications

HIV infection has progressed from an acute, terminal disease to a chronic illness with cardiovascular disease as the leading cause of death among persons living with HIV. As persons living with HIV infection continue to become older, traditional risk factors for atherosclerosis compounded by the pathophysiological effects of HIV infection and antiretroviral therapy markedly increase the risk for cardiovascular disease. Further, persons living with HIV are also at high risk for cardiomyopathy. Critical care nurses must recognize the risk factors for cardiovascular disease and the pathophysiology and complex treatment options in order to manage care of these patients and facilitate multidisciplinary collaboration. Two case studies are used to highlight the treatment options and nursing considerations associated with cardiovascular disease among persons living with HIV.

The homozygous CX3CR1-M280 mutation impairs human monocyte survival

Several reports have demonstrated that mouse Cx3cr1 signaling promotes monocyte/macrophage survival. In agreement, we previously found that, in a mouse model of systemic candidiasis, genetic deficiency of Cx3cr1 resulted in increased mortality and impaired tissue fungal clearance associated with decreased macrophage survival. We translated this finding by showing that the dysfunctional CX3CR1 variant CX3CR1-M280 was associated with increased risk and worse outcome of human systemic candidiasis. However, the impact of this mutation on human monocyte/macrophage survival is poorly understood. Herein, we hypothesized that CX3CR1-M280 impairs human monocyte survival. We identified WT (CX3CR1-WT/WT), CX3CR1-WT/M280 heterozygous, and CX3CR1-M280/M280 homozygous healthy donors of European descent, and we show that CX3CL1 rescues serum starvation-induced cell death in CX3CR1-WT/WT and CX3CR1-WT/M280 but not in CX3CR1-M280/M280 monocytes. CX3CL1-induced survival of CX3CR1-WT/WT monocytes is mediated via AKT and ERK activation, which are both impaired in CX3CR1-M280/M280 monocytes, associated with decreased blood monocyte counts in CX3CR1-M280/M280 donors at steady state. Instead, CX3CR1-M280/M280 does not affect monocyte CX3CR1 surface expression or innate immune effector functions. Together, we show that homozygocity of the M280 polymorphism in CX3CR1 is a potentially novel population-based genetic factor that influences human monocyte signaling.

Oceanic protists with different forms of acquired phototrophy display contrasting biogeographies and abundance

This first comprehensive analysis of the global biogeography of marine protistan plankton with acquired phototrophy shows these mixotrophic organisms to be ubiquitous and abundant; however, their biogeography differs markedly between different functional groups. These mixotrophs, lacking a constitutive capacity for photosynthesis (i.e. non-constitutive mixotrophs, NCMs), acquire their phototrophic potential through either integration of prey-plastids or through endosymbiotic associations with photosynthetic microbes. Analysis of field data reveals that 40-60% of plankton traditionally labelled as (non-phototrophic) microzooplankton are actually NCMs, employing acquired phototrophy in addition to phagotrophy. Specialist NCMs acquire chloroplasts or endosymbionts from specific prey, while generalist NCMs obtain chloroplasts from a variety of prey. These contrasting functional types of NCMs exhibit distinct seasonal and spatial global distribution patterns. Mixotrophs reliant on 'stolen' chloroplasts, controlled by prey diversity and abundance, dominate in high-biomass areas. Mixotrophs harbouring intact symbionts are present in all waters and dominate particularly in oligotrophic open ocean systems. The contrasting temporal and spatial patterns of distribution of different mixotroph functional types across the oceanic provinces, as revealed in this study, challenges traditional interpretations of marine food web structures. Mixotrophs with acquired phototrophy (NCMs) warrant greater recognition in marine research.

Intraoperative use of a transarticular circular fixator construct to facilitate reduction and stabilisation of a proximal tibial physeal fracture in a dog

CASE REPORT

A 4-month-old female intact American Pit Bull Terrier was presented for right pelvic limb lameness 1 day after the dog had been hit by an all-terrain vehicle. Orthogonal radiographs of the right stifle revealed a Salter-Harris type IV fracture through the proximal tibial physis extending caudodistally through the proximal tibial metaphysis. The distal tibia was markedly displaced cranially, laterally and proximally, resulting in complete overriding of the fracture segments. An open approach was made in order to facilitate direct reduction, but the fracture could not be sufficiently distracted and the epiphyseal segment remained fixed caudal to the remainder of the tibia. Concerns regarding possible iatrogenic trauma to the epiphysis prompted the use of a transarticular circular fixator construct to distract the fracture segments to facilitate reduction. Distraction that facilitated reduction was performed using three TrueLok Rapid Quick Adjust Struts that were positioned between the two ring components. The struts also allowed for multiplanar adjustment of alignment, which allowed the fracture to be maintained in anatomic reduction as divergent interfragmentary Kirschner wires were placed. Radiographic union was confirmed 19 days after surgery.

CONCLUSION/CLINICAL SIGNIFICANCE

Transient intraoperative application of a circular construct incorporating the TrueLok components facilitated accurate fracture reduction without inflicting further iatrogenic trauma to the epiphysis, after traditional direct reduction techniques proved ineffective, and afforded a successful clinical outcome in the dog reported here.

Measuring Absolute Blood Perfusion in Mice Using Dynamic Contrast-Enhanced Ultrasound

We investigated the feasibility of estimating absolute tissue blood perfusion using dynamic contrast-enhanced ultrasound (CEUS) imaging in mice. We developed a novel method of microbubble administration and a model-free approach to estimate absolute kidney perfusion, and explored the kidney as a reference organ to estimate absolute perfusion of a neuroblastoma tumor. We performed CEUS on the kidneys of CD1 nude mice using the VisualSonics VEVO 2100 imaging system. We estimated individual kidney blood perfusion using the burst-replenishment (BR) technique. We repeated the kidney imaging on the mice after a week. We performed CEUS imaging of a neuroblastoma mouse xenograft tumor along with its right kidney using two sets of microbubble administration parameters to estimate absolute tumor blood perfusion. We performed statistical tests at a significance level of 0.05. Our estimated absolute kidney perfusion (425 ± 123 mL/min/100 g) was within the range of previously reported values. There was no statistical difference between the estimated absolute kidney blood perfusions from the 2 wk of imaging (paired t-test, p = 0.09). We estimated the absolute blood perfusion in the neuroblastoma tumor to be 16.49 and 16.9 mL/min/100 g for the two sets of microbubble administration parameters (Wilcoxon rank-sum test, p = 0.6). We have established the kidney as a reliable reference organ in which to estimate absolute perfusion of other tissues. Using a neuroblastoma tumor, we have determined the feasibility of estimating absolute blood perfusion in tissues using contrast-enhanced ultrasound imaging.

An integrative genomics approach identifies novel pathways that influence candidaemia susceptibility

Candidaemia is a bloodstream infection caused by Candida species that primarily affects specific groups of at-risk patients. Because only small candidaemia patient cohorts are available, classical genome wide association cannot be used to identify Candida susceptibility genes. Therefore, we have applied an integrative genomics approach to identify novel susceptibility genes and pathways for candidaemia. Candida-induced transcriptome changes in human primary leukocytes were assessed by RNA sequencing. Genetic susceptibility to candidaemia was assessed using the Illumina immunochip platform for genotyping of a cohort of 217 patients. We then integrated genetics data with gene-expression profiles, Candida-induced cytokine production capacity, and circulating concentrations of cytokines. Based on the intersection of transcriptome pathways and genomic data, we prioritized 31 candidate genes for candidaemia susceptibility. This group of genes was enriched with genes involved in inflammation, innate immunity, complement, and hemostasis. We then validated the role of MAP3K8 in cytokine regulation in response to Candida stimulation. Here, we present a new framework for the identification of susceptibility genes for infectious diseases that uses an unbiased, hypothesis-free, systems genetics approach. By applying this approach to candidaemia, we identified novel susceptibility genes and pathways for candidaemia, and future studies should assess their potential as therapeutic targets.

CXCR1-mediated neutrophil degranulation and fungal killing promote Candida clearance and host survival

Systemic Candida albicans infection causes high morbidity and mortality and is now the leading cause of nosocomial bloodstream infection in the United States. Neutropenia is a major risk factor for poor outcome in infected patients; however, the molecular factors that mediate neutrophil trafficking and effector function during infection are poorly defined. Using a mouse model of systemic candidiasis, we found that the neutrophil-selective CXC chemokine receptor Cxcr1 and its ligand, Cxcl5, are highly induced in the Candida-infected kidney, the target organ in the model. To investigate the role of Cxcr1 in antifungal host defense in vivo, we generated Cxcr1(-/-) mice and analyzed their immune response to Candida. Mice lacking Cxcr1 exhibited decreased survival with enhanced Candida growth in the kidney and renal failure. Increased susceptibility of Cxcr1(-/-) mice to systemic candidiasis was not due to impaired neutrophil trafficking from the blood into the infected kidney but was the result of defective killing of the fungus by neutrophils that exhibited a cell-intrinsic decrease in degranulation. In humans, the mutant CXCR1 allele CXCR1-T276 results in impaired neutrophil degranulation and fungal killing and was associated with increased risk of disseminated candidiasis in infected patients. Together, our data demonstrate a biological function for mouse Cxcr1 in vivo and indicate that CXCR1-dependent neutrophil effector function is a critical innate protective mechanism of fungal clearance and host survival in systemic candidiasis.

The influence of taste in willingness-to-pay valuations of sirloin steaks from postextraction algal residue-fed cattle

Consumer preferences and willingness-to-pay (WTP) for beef sirloin steaks with differing production, physical, and credence attributes related to the use of postextraction algal residue (PEAR), a novel feed ingredient, were estimated. Ninety-six consumers participated in a sensory tasting panel before completing a choice set survey; 127 consumers completed only the choice set survey without sampling products. Steaks from grain- and PEAR-fed steers had similar Warner-Bratzler shear force (WBSF) scores (1.89 kg and 2.01 kg, respectively; = 0.77) and had lower WBSF scores than steaks from grass-fed steers (3.37 kg; < 0.05). Eicosapentaenoic acid (20:5) was not different among steaks from grain- and PEAR-fed steers ( = 0.39) but was greater compared with steaks from grass-fed cattle ( ≤ 0.03). Panelists in the sensory portion of the study evaluated beef samples for like/dislike of overall sample, overall flavor, beefy flavor, and juiciness. Panelist rating of overall like, overall flavor like, and beefy flavor like were not different between the PEAR- and grain-fed treatments ( > 0.26). Panelists rated the juiciness like/dislike of steaks from PEAR-fed cattle the highest ( < 0.01) among the 3 samples. Sensory tasting of the products was observed to alter the preferences of consumers. Consumers who completed only the survey negatively perceived beef from PEAR-fed cattle compared with beef from grain-fed cattle, with a WTP discount of -US$1.17/kg. However, with sensory tasting, the WTP for beef from PEAR-fed cattle was not discounted relative to beef from grain-fed cattle ( = 0.21). The nontasting consumers had much higher stated WTP values for credence attributes. Factors that influence the eating experience (tenderness and quality grade) dominated as the most important attributes on WTP among the tasting group. The use of no hormones and no antibiotics in production had a premium of $2.34/kg among the nontasting group, but with tasting, the premium was $1.19/kg. If PEAR-fed beef came to market, there would be no need to differentiate it from grain-fed beef unless retailers wanted to market it as a differentiated product. If it were marketed as a differentiated product, retailers would need to hold promotional tastings to change consumer's preconceived notions about the product.

Short-term risk of liver and renal injury in hospitalized patients using micafungin: a multicentre cohort study

BACKGROUND

Although echinocandins are generally well tolerated, there is little information on the frequency with which renal and hepatic adverse effects occur during use of micafungin or other parenteral antifungal (PAF) agents in clinical practice.

METHODS

MYCOS is a multicentre cohort study of adult and paediatric patients who received micafungin or other PAFs between 2005 and 2012 at seven tertiary care hospitals from six centres in the USA. PAF cohort controls were selected through propensity score (PS) matching to micafungin recipients using clinical characteristics, other treatments, procedures and hospital service where PAF treatment was initiated. Analysis was restricted to patients without chronic liver and kidney conditions at the time of cohort entry. Treatment-emergent hepatic and renal injury was documented by changes in liver enzymes or estimated glomerular filtration rate through 30 days following completion of PAF treatment. Comparisons were quantified using the HR from a proportional hazards analysis.

RESULTS

There were 2970 micafungin recipients PS matched to 6726 recipients of comparator PAFs. Balance was achieved in all baseline covariates between treatment groups. There were similar rates of hepatic injury (micafungin, 13 events per 100 patients and other PAF, 12 per 100; HR = 0.99; 95% CI 0.86-1.14) and lower rates of renal injury (micafungin, 63 events per 100 patients and other PAF, 65 per 100; HR = 0.93; 95% CI 0.87-0.99) for micafungin recipients versus PAF comparators.

CONCLUSION

For a wide spectrum of underlying conditions, we observed no increase in liver injury by micafungin and possibly a reduced risk of renal dysfunction in comparison with other PAF medications.

Genetic Susceptibility to Fungal Infections: What is in the Genes?

The development of severe fungal infections has long been associated with traditional risk factors such as profound immunosuppression, yet it remains challenging to understand why under similar conditions only some patients will develop these infections while others will not. Recent studies have demonstrated the importance of host genetic variation in influencing the severity and susceptibility to invasive fungal infections (IFIs). In this review, we examine selected primary immunodeficiencies characterized by their vulnerability to a narrow range of fungal pathogens, and then focus on recently identified genetic polymorphisms associated with an increased susceptibility to IFIs.

Physiological changes in the pallidum in a progressive model of Parkinson's disease: Are oscillations enough?

Neurophysiological changes in the basal ganglia thalamo-cortical circuit associated with the development of parkinsonian motor signs remain poorly understood. Theoretical models have ranged from those emphasizing changes in mean discharge rate to increased oscillatory activity within the beta range. The present study characterized neuronal activity within and across the internal and external segments of the globus pallidus as a function of motor severity using a staged, progressively severe 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine model of Parkinsonism in three rhesus monkeys. An increase in coherence between neuronal pairs across the external and internal globus pallidus was present in multiple frequency bands in the parkinsonian state; both the peak frequency of oscillatory coherence and the variability were reduced in the parkinsonian state. The incidence of 8-20Hz oscillatory activity in the internal globus pallidus increased with the progression of the disease when pooling the data across the three animals; however it did not correlate with motor severity when assessed individually and increased progressively in only one of three animals. No systematic relationship between mean discharge rates or the incidence or structure of bursting activity and motor severity was observed. These data suggest that exaggerated coupling across pallidal segments contribute to the development of the parkinsonian state by inducing an exaggerated level of synchrony and loss of focusing within the basal ganglia. These data further point to the lack of a defined relationship between rate changes, the mere presence of oscillatory activity in the beta range and bursting activity in the basal ganglia to the motor signs of Parkinson's disease.

Collaborative drug therapy management and comprehensive medication management-2015

The American College of Clinical Pharmacy (ACCP) previously published position statements on collaborative drug therapy management (CDTM) in 1997 and 2003. Since 2003, significant federal and state legislation addressing CDTM has evolved and expanded throughout the United States. CDTM is well suited to facilitate the delivery of comprehensive medication management (CMM) by clinical pharmacists. CMM, defined by ACCP as a core component of the standards of practice for clinical pharmacists, is designed to optimize medication-related outcomes in collaborative practice environments. New models of care delivery emphasize patient-centered, team-based care and increasingly link payment to the achievement of positive economic, clinical, and humanistic outcomes. Hence clinical pharmacists practicing under CDTM agreements or through other privileging processes are well positioned to provide CMM. The economic value of clinical pharmacists in team-based settings is well documented. However, patient access to CMM remains limited due to lack of payer recognition of the value of clinical pharmacists in collaborative care settings and current health care payment policy. Therefore, the clinical pharmacy discipline must continue to establish and expand its use of CDTM agreements and other collaborative privileging mechanisms to provide CMM. Continued growth in the provision of CMM by appropriately qualified clinical pharmacists in collaborative practice settings will enhance recognition of their positive impact on medication-related outcomes.

The RIG-I-like helicase receptor MDA5 (IFIH1) is involved in the host defense against Candida infections

The induction of host defense against Candida species is initiated by recognition of the fungi by pattern recognition receptors and activation of downstream pathways that produce inflammatory mediators essential for infection clearance. In this study, we present complementary evidence based on transcriptome analysis, genetics, and immunological studies in knockout mice and humans that the cytosolic RIG-I-like receptor MDA5 (IFIH1) has an important role in the host defense against C. albicans. Firstly, IFIH1 expression in macrophages is specifically induced by invasive C. albicans hyphae, and patients suffering from chronic mucocutaneous candidiasis (CMC) express lower levels of MDA5 than healthy controls. Secondly, there is a strong association between missense variants in the IFIH1 gene (rs1990760 and rs3747517) and susceptibility to systemic Candida infections. Thirdly, cells from Mda5 knockout mice and human peripheral blood mononuclear cells (PBMCs) with different IFIH1 genotypes display an altered cytokine response to C. albicans. These data strongly suggest that MDA5 is involved in immune responses to Candida infection. As a receptor for viral RNA, MDA5 until now has been linked to antiviral host defense, but these novel studies show unexpected effects in antifungal immunity as well. Future studies are warranted to explore the potential of MDA5 as a novel target for immunotherapeutic strategies.

The discriminative capacity of soluble Toll-like receptor (sTLR)2 and sTLR4 in inflammatory diseases

Background

The extracellular domains of cytokine receptors are released during inflammation, but little is known about the shedding of Toll-like receptors (TLR) and whether they can be used as diagnostic biomarkers.

Methods

The release of sTLR2 and sTLR4 was studied in in-vitro stimulations, as well as in-vivo during experimental human endotoxemia (n = 11, 2 ng/kg LPS), and in plasma of 394 patients with infections (infectious mononucleosis, measles, respiratory tract infections, bacterial sepsis and candidemia) or non-infectious inflammation (Crohn’s disease, gout, rheumatoid arthritis, autoinflammatory syndromes and pancreatitis). Using C-statistics, the value of sTLR2 and sTLR4 levels for discrimination between infections and non-infectious inflammatory diseases, as well as between viral and bacterial infections was analyzed.

Results

In-vitro, peripheral blood mononuclear cells released sTLR2 and sTLR4 by exposure to microbial ligands. During experimental human endotoxemia, plasma concentrations peaked after 2 hours (sTLR4) and 4 hours (sTLR2). sTLR4 did not correlate with cytokines, but sTLR2 correlated positively with TNFα (r_s = 0.80, P < 0.05), IL-6 (r_s = 0.65, P < 0.05), and IL-1Ra (r_s = 0.57, P = 0.06), and negatively with IL-10 (r_s = -0.58, P = 0.06), respectively. sTLR4 had a similar area under the ROC curve [AUC] for differentiating infectious and non-infectious inflammation compared to CRP: 0.72 (95% CI 0.66-0.79) versus 0.74 (95% CI 0.69-0.80) [P = 0.80], while sTLR2 had a lower AUC: 0.60 (95% CI 0.54-0.66) [P = 0.0004]. CRP differentiated bacterial infections better from viral infections than sTLR2 and sTLR4: AUC 0.94 (95% CI 0.90-0.96) versus 0.58 (95% CI 0.51-0.64) and 0.75 (95% CI 0.70-0.80), respectively [P < 0.0001 for both].

Conclusions

sTLRs are released into the circulation, and suggest the possibility to use sTLRs as diagnostic tool in inflammatory conditions.