Jaap ten Oever

The bacteriome-mycobiome interaction and antifungal host defense.

Large communities of microorganisms, collectively termed the microbiome, inhabit our body surfaces. With the advent of next‐generation sequencing, the diversity and abundance of these communities are being unravelled. Besides an imporant role in metabolic processes, the microbiome is essential for proper functioning of our immune system, including the defense against fungi. Despite the progress of the past years, studies aimed at characterizing our fungal colonizers (the mycobiome) are limited; nevertheless fungi are important players of the microbiome, either as a cofactor in disease or as potential pathogens. In this review, we describe the role of the bacterial microbiome in antifungal host defense. On the one hand, bacteria provide colonization resistance to fungi, inhibit Candida virulence by preventing yeast‐hyphal transition and contribute to epithelial integrity, all factors are important for the pathogenesis of invasive fungal disease. On the other hand, several bacterial species modulate mucosal (antifungal) immune responses. Murine studies demonstrate important effects of the microbiome on the antifungal responses of T‐helper 17 cells, regulatory T cells and innate lymphoid cells. Inferred from these studies, perturbation of the healthy microbiome should be avoided and microbiome manipulation and interventions based on bacteria‐derived pathways involved in immunomodulation are attractive options for modulating antifungal host defense.

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

BackgroundThe 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.MethodsThe 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.ResultsIn-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 (rs = 0.80, P < 0.05), IL-6 (rs = 0.65, P < 0.05), and IL-1Ra (rs = 0.57, P = 0.06), and negatively with IL-10 (rs = -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].ConclusionssTLRs are released into the circulation, and suggest the possibility to use sTLRs as diagnostic tool in inflammatory conditions.

Utility of immune response-derived biomarkers in the differential diagnosis of inflammatory disorders

Differentiating between inflammatory disorders is difficult, but important for a rational use of antimicrobial agents. Biomarkers reflecting the host immune response may offer an attractive strategy to predict the etiology of an inflammatory process and can thus be of help in decision making. We performed a review of the literature to evaluate the diagnostic value of inflammatory biomarkers in adult patients admitted to the hospital with suspected systemic acute infections. Elevated procalcitonin (PCT) concentrations indicate a bacterial infection in febrile patients with an auto-immune disease, rather than a disease flare. CD64 expression on neutrophils can discriminate between non-infectious systemic inflammation and sepsis, and limited evidence suggests the same for decoy receptor 3. PCT is useful for both diagnosing bacterial infection complicating influenza and guiding antibiotic treatment in lower respiratory tract infections in general. In undifferentiated illnesses, increased CD35 expression on neutrophils distinguishes bacterial from viral infections. Compared to bacterial infections, invasive fungal infections are characterized by low concentrations of PCT. No biomarker predicting a specific infecting agent could be identified.

18F-FDG PET/CT optimizes treatment in staphylococcus aureus bacteremia and is associated with reduced mortality

Metastatic infection is an important complication of Staphylococcus aureus bacteremia (SAB). Early diagnosis of metastatic infection is crucial, because specific treatment is required. However, metastatic infection can be asymptomatic and difficult to detect. In this study, we investigated the role of 18F-FDG PET/CT in patients with SAB for detection of metastatic infection and its consequences for treatment and outcome. Methods: All patients with SAB at Radboud University Medical Center were included between January 2013 and April 2016. Clinical data and results of 18F-FDG PET/CT and other imaging techniques, including echocardiography, were collected. Primary outcomes were newly diagnosed metastatic infection by 18F-FDG PET/CT, subsequent treatment modifications, and patient outcome. Results: A total of 184 patients were included, and 18F-FDG PET/CT was performed in 105 patients, of whom 99 had a high-risk bacteremia. 18F-FDG PET/CT detected metastatic infectious foci in 73.7% of these high-risk patients. In 71.2% of patients with metastatic infection, no signs and symptoms suggesting metastatic complications were present before 18F-FDG PET/CT was performed. 18F-FDG PET/CT led to a total of 104 treatment modifications in 74 patients. Three-month mortality was higher in high-risk bacteremia patients without 18F-FDG PET/CT performed than in those in whom 18F-FDG PET/CT was performed (32.7% vs. 12.4%, P = 0.003). In multivariate analysis, 18F-FDG PET/CT was the only factor independently associated with reduced mortality (P = 0.005; odds ratio, 0.204; 95% confidence interval, 0.066–0.624). A higher comorbidity score was independently associated with increased mortality (P = 0.003; odds ratio, 1.254; 95% confidence interval, 1.078–1.457). Conclusion: 18F-FDG PET/CT is a valuable technique for early detection of metastatic infectious foci, often leading to treatment modification. Performing 18F-FDG PET/CT is associated with significantly reduced 3-mo mortality.

The Effect of Rosuvastatin on Markers of Immune Activation in Treatment-Naive Human Immunodeficiency Virus-Patients

Background. Immune activation has been implicated in the excess mortality in human immunodeficiency virus (HIV)-infected patients, due to cardiovascular diseases and malignancies. Statins may modulate this immune activation. We assessed the capacity of rosuvastatin to mitigate immune activation in treatment-naive HIV-infected patients. Methods. In a randomized double-blind placebo-controlled crossover study, we explored the effects of 8 weeks of rosuvastatin 20 mg in treatment-naive male HIV-infected patients (n = 28) on immune activation markers: neopterin, soluble Toll-like receptor (TLR)2, sTLR4, interleukin (IL)-6, IL-1Ra, IL-18, d-dimer, highly sensitive C-reactive protein, and CD38 and/or human leukocyte antigen-DR expression on T cells. Baseline data were compared with healthy male controls (n = 10). Furthermore, the effects of rosuvastatin on HIV-1 RNA, CD4/CD8 T-cell count, and low-density lipoprotein cholesterol were examined and side effects were registered. Results. T-cell activation levels were higher in patients than in controls. Patients had higher levels of circulating IL-18, sTLR2, and neopterin (all P < .01). Twenty patients completed the study. Rosuvastatin increased the CD4/CD8 T-cell ratio (P = .02). No effect on other markers was found. Conclusions. Patients infected with HIV had higher levels of circulating neopterin, IL-18, sTLR2, and T-cell activation markers. Rosuvastatin had a small but significant positive effect on CD4/CD8 T-cell ratio, but no influence on other markers of T-cell activation and innate immunity was identified (The Netherlands National Trial Register [NTR] NTR 2349, http://www.trialregister.nl/trialreg/index.asp).

Monitoring, documenting and reporting the quality of antibiotic use in the Netherlands: a pilot study to establish a national antimicrobial stewardship registry

BackgroundThe Dutch Working Party on Antibiotic Policy is developing a national antimicrobial stewardship registry. This registry will report both the quality of antibiotic use in hospitals in the Netherlands and the stewardship activities employed. It is currently unclear which aspects of the quality of antibiotic use are monitored by antimicrobial stewardship teams (A-teams) and can be used as indicators for the stewardship registry. In this pilot study we aimed to determine which stewardship objectives are eligible for the envisioned registry.MethodsWe performed an observational pilot study among five Dutch hospitals. We assessed which of the 14 validated stewardship objectives (11 process of care recommendations and 3 structure of care recommendations) the A-teams monitored and documented in individual patients. They provided, where possible, data to compute quality indicator (QI) performance scores in line with recently developed QIs to measure appropriate antibiotic use in hospitalized adults for the period of January 2015 through December 2015ResultsAll hospitals had a local antibiotic guideline describing recommended antimicrobial use. All A-teams monitored the performance of bedside consultations in Staphylococcus aureus bacteremia and the prescription of restricted antimicrobials. Documentation and reporting were the best for the use of restricted antimicrobials: 80% of the A-teams could report data. Lack of time and the absence of an electronic medical record system enabling documentation during the daily work flow were the main barriers hindering documentation and reporting.ConclusionsFive out of 11 stewardship objectives were actively monitored by A-teams. Without extra effort, 4 A-teams could report on the quality of use of restricted antibiotics. Therefore, this aspect of antibiotic use should be the starting point of the national antimicrobial stewardship registry. Our registry is expected to become a powerful tool to evaluate progress and impact of antimicrobial stewardship programs in hospitals.

Cytokine Production Assays Reveal Discriminatory Immune Defects in Adults with Recurrent Infections and Noninfectious Inflammation

ABSTRACT Cytokine production assays have been primarily used in research settings studying novel immunodeficiencies. We sought to determine the diagnostic value of cytokine production assays in patients with recurrent and/or severe infectious diseases (IDs) without known immunodeficiencies and unclassified noninfectious inflammatory disorders (NIIDs). We retrospectively examined cytokine production in whole-blood and peripheral blood mononuclear cell samples from 157 adult patients. A cytokine production rate of <5% of that of healthy controls was considered defective. While monocyte-derived cytokine (tumor necrosis factor alpha [TNF-α], interleukin-1β [IL-1β], and IL-6) production was rarely affected, 30% of all included patients had deficient production of interferon gamma (IFN-γ), IL-17A, or IL-22. Twenty-five percent of the NIID patients displayed defective IFN-γ production, whereas IL-17A production was generally unaffected. In the group of ID patients, defective IFN-γ production was found in 19% and 14% of the patients with viral and bacterial infections, respectively, and in 38%, 24%, and 50% of patients with mycobacterial, mucocutaneous, and invasive fungal infections, respectively. Defective IL-17A and IL-22 production was mainly confined to ID patients with mucocutaneous fungal infections. In conclusion, cytokine production assays frequently detect defective Th1 responses in patients with mycobacterial or fungal infections, in contrast to patients with respiratory tract infections or isolated bacterial infections. Defective IL-17A and IL-22 production was primarily found in patients with fungal infections, while monocyte-derived cytokine production was unaffected. Thus, lymphocyte-derived cytokine production assays are helpful in the diagnostic workup of patients with recurrent infections and suspected immunodeficiencies and have the potential to reveal immune defects that might guide adjunctive immunomodulatory therapy.

Legal framework of antimicrobial stewardship in hospitals (LEASH): a European Society of Clinical Microbiology and Infectious Diseases (ESCMID) cross-sectional international survey

Antimicrobial stewardship (AMS) is the cornerstone activity in the combat against antimicrobial resistance. In order to ensure sustainable deployment and development of AMS, a strategic and regulatory framework needs to be provided by national healthcare authorities. Experts from 32 European countries, Israel and Turkey were invited to participate in a cross-sectional internet-based survey from October 2016 to May 2017 on the legal framework and mandatory components (structures, activities) of AMS in hospitals, i.e. components required by legislation or regulations. We collected data from 25 countries and two regions (in countries with federal health administration). Laws regulating AMS existed in seven countries and one region. Other health ministry regulations were applicable in 13 countries and one region. National strategies and/or action plans approved by ministries of health were in place in 13 countries and one region. Conversely, five countries and one region had no regulation of AMS in hospitals. Funding for AMS in hospitals was provided in five countries and one region. Eight countries and one region reported mandatory AMS structures and activities complying with the Transatlantic Taskforce on Antimicrobial Resistance (TATFAR) structure, policy and practice indicators. In 10/27 cases, however, the mandatory AMS activities were not being fully carried out. The survey showed heterogeneous legal frameworks for AMS in hospitals, and in many countries it was even lacking. The situation may be critical in countries with poor control of antimicrobial use and resistance. Recent international initiatives calling on policy-makers to address the threat of antimicrobial resistance could yield improvement.