Eosinophils: Nemeses of Pulmonary Pathogens?

PURPOSE OF REVIEW

Eosinophils are short-lived granulocytes that contain a variety of proteins and lipids traditionally associated with host defense against parasites. The primary goal of this review is to examine more recent evidence that challenged this rather outdated role of eosinophils in the context of pulmonary infections with helminths, viruses, and bacteria.

RECENT FINDINGS

While eosinophil mechanisms that counter parasites, viruses, and bacteria are similar, the kinetics and impact may differ by pathogen type. Major antiparasitic responses include direct killing and immunoregulation, as well as some mechanisms by which parasite survival/growth is supported. Antiviral defenses may be as unembellished as granule protein-induced direct killing or more urbane as serving as a conduit for better adaptive immune responses to the invading virus. Although sacrificial, eosinophil DNA emitted in response to bacteria helps trap bacteria to limit dissemination. Herein, we discuss the current research redefining eosinophils as multifunctional cells that are active participants in host defense against lung pathogens. Eosinophils recognize and differentially respond to invading pathogens, allowing them to deploy innate defense mechanisms to contain and clear the infection, or modulate the immune response. Modern technology and animal models have unraveled hitherto unknown capabilities of this surreptitious cell that indubitably has more functions awaiting discovery.

Duration of frequent or severe respiratory tract infection in adults before diagnosis of IgG subclass deficiency

Many adults with IgG subclass deficiency (IgGSD) experience long intervals of frequent/severe respiratory tract infection before IgGSD diagnosis, but reasons for delays in IgGSD diagnoses are incompletely understood. We performed a retrospective study of 300 white adults (ages ≥18 y) with IgGSD including frequency analyses of age at IgGSD diagnosis, duration of frequent/severe respiratory tract infection before IgGSD diagnosis, and age at onset of frequent/severe infection (calculated). We performed multivariable regressions on age at diagnosis, infection duration, and age at infection onset using these variables, as appropriate: sex; age at diagnosis; diabetes; autoimmune condition(s); atopy; allergy; corticosteroid use; body mass index; serum immunoglobulin isotype levels; blood lymphocyte subsets; three IgGSD-associated human leukocyte antigen-A and -B haplotypes; and referring physician specialties. Mean age at diagnosis was 50 ± 12 (standard deviation) y (median 50 y (range 19–79)). There were 247 women (82.3%). Mean infection duration at IgGSD diagnosis was 12 ± 13 y (median 7 y (range 1–66)). Mean age at infection onset was 38 ± 16 y (median 38 y (range 4, 76)). Age at infection onset was ≥18 y in 95.7% of subjects. Regressions on age at diagnosis and infection duration revealed no significant associations. Regression on age at infection onset revealed one positive association: age at diagnosis (p <0.0001). We conclude that the median duration of frequent/severe respiratory tract infection in adults before IgGSD diagnosis was 7 y. Older adults may be diagnosed to have IgGSD after longer intervals of infection than younger adults. Duration of frequent/severe respiratory tract infection before IgGSD diagnosis was not significantly associated with routine clinical and laboratory variables, including referring physician specialties.

Differences in plasma amino acid levels in patients with and without bacterial infection during the early stage of acute exacerbation of COPD

PURPOSE

No consensus has been reached regarding appropriate nutritional intervention and rehabilitation during early acute exacerbation of COPD (AECOPD). Given the individual differences in symptoms of AECOPD, patients should be classified by their pathology. For example, it is known that there are differences in the inflammatory response between AECOPD with and without bacterial infection. However, there have been few reports on AECOPD from a nutritional perspective. The aim of this study was to investigate amino acid levels in patients with AECOPD.

PATIENTS AND METHODS

Blood was collected from patients who were hospitalized with AECOPD and from patients with COPD that was in a stable state. We divided the patients with AECOPD into those without bacterial infection (group A) and those with bacterial infection (group B). The patients with COPD that was stable served as controls (group C). The plasma levels of 9 essential amino acids, 13 nonessential amino acids, and total amino acids were compared between the three groups.

RESULTS

In the early stages of AECOPD, differences in plasma levels of only three amino acids (glycine, phenylalanine, and arginine) were observed between groups C and A. Differences in total amino acids and 13 amino acids were observed between groups C and B. Group B had lower levels of total amino acids and of seven amino acids (asparagine, citrulline, glutamine, histidine, methionine, serine, and threonine) compared with the other study groups.

CONCLUSION

The findings of this study show that amino acid levels in plasma differ in patients with AECOPD depending on whether or not bacterial infection is present. Our results suggest that specific amino acids (ie, asparagine, citrulline, glutamine, histidine, serine, and threonine) have potential utility as diagnostic markers to distinguish between bacterial and nonbacterial AECOPD.

Respiratory infections drive hepcidin-mediated blockade of iron absorption leading to iron deficiency anemia in African children

Iron deficiency anemia (IDA) is the most prevalent nutritional condition worldwide. We studied the contribution of hepcidin-mediated iron blockade to IDA in African children. We measured hepcidin and hemoglobin weekly, and hematological, inflammatory, and iron biomarkers at baseline, 7 weeks, and 12 weeks in 407 anemic (hemoglobin < 11 g/dl), otherwise healthy Gambian children (6 to 27 months). Each child maintained remarkably constant hepcidin levels (P < 0.0001 for between-child variance), with half consistently maintaining levels that indicate physiological blockade of iron absorption. Hepcidin was strongly predicted by nurse-ascribed adverse events with dominant signals from respiratory infections and fevers (all P < 0.0001). Diarrhea and fecal calprotectin were not associated with hepcidin. In multivariate analysis, C-reactive protein was the dominant predictor of hepcidin and contributed to iron blockade even at very low levels. We conclude that even low-grade inflammation, especially associated with respiratory infections, contributes to IDA in African children.

Risk Factors for Parainfluenza Virus Lower Respiratory Tract Disease after Hematopoietic Cell Transplantation

Parainfluenza virus (PIV) infection can progress from upper respiratory tract infection (URTI) to lower respiratory tract disease (LRTD) in immunocompromised hosts. Risk factors for progression to LRTD and presentation with LRTD without prior URTI are poorly defined. Hematopoietic cell transplant (HCT) recipients with PIV infection were retrospectively analyzed using standardized definitions of LRTD. PIV was detected in 540 HCT recipients; 343 had URTI alone and 197 (36%) had LRTD (possible, 76; probable, 19; proven, 102). Among 476 patients with positive nasopharyngeal samples, the cumulative incidence of progression to probable/proven LRTD by day 40 was 12%, with a median time to progression of 7 days (range, 2 to 40). In multivariable analysis monocytopenia (hazard ratio, 2.22; P = .011), steroid use ≥1mg/kg prior to diagnosis (hazard ratio, 1.89; P = .018), co-pathogen detection in blood (hazard ratio, 3.21; P = .027), and PIV type 3 (hazard ratio, 3.57; P = .032) were associated with increased progression risk. In the absence of all 4 risk factors no patients progressed to LRTD, whereas progression risk increased to >30% if 3 or more risk factors were present. Viral load or ribavirin use appeared to have no effect on progression. Among 121 patients with probable/proven LRTD, 64 (53%) presented LRTD without prior URTI, and decreased lung function before infection and lower respiratory co-pathogens were risk factors for this presentation. Mortality was unaffected by the absence of prior URTI. We conclude that the risk of progression to probable/proven LRTD exceeded 30% with ≥3 risk factors. To detect all cases of LRTD, virologic testing of lower respiratory samples is required regardless of URTI symptoms.

[Systemic biomarkers in respiratory tract infections]

Respiratory tract infections represent a major cause of morbidity and mortality despite the progress made in their diagnosis and treatment. Since the clinical presentation of a viral or bacterial infection is often similar, the identification of a biomarker that could guide the clinician whether or not to introduce an antibiotic therapy is crucial. C-reactive protein and procalcitonin are the most commonly used biomarkers as a diagnostic tool for respiratory tract infections. New biomarkers show promising results for assessing the severity of infection and identifying patients at risk for complications. However, the use of biomarkers has limitations and the diagnosis of a bacterial infection should not be based solely on the measurement of a biomarker.

C-reactive protein point of care testing in the management of acute respiratory infections in the Vietnamese primary healthcare setting - a cost benefit analysis

Aim

We assess the cost-benefit implications of C-reactive protein (CRP) testing in reducing antibiotic prescription for acute respiratory infection in Viet Nam by comparing the incremental costs of CRP testing with the economic costs of antimicrobial resistance averted due to lower antibiotic prescribing.

Findings

Patients in the CRP group and the controls incurred similar costs in managing their illness, excluding the costs of the quantitative CRP tests, provided free of charge in the trial context. Assuming a unit cost of $1 per test, the incremental cost of CRP testing was $0.93 per patient. Based on a previous modelling analysis, the 20 percentage point reduction in prescribing observed in the trial implies a societal benefit of $0.82 per patient. With the low levels of adherence to the test results observed in the trial, CRP testing would not be cost-beneficial. The sensitivity analyses showed, however, that with higher adherence to test results their use would be cost-beneficial.

Respiratory Bordetella bronchiseptica Carriage is Associated with Broad Phenotypic Alterations of Peripheral CD4⁺CD25⁺ T Cells and Differentially Affects Immune Responses to Secondary Non-Infectious and Infectious Stimuli in Mice

The respiratory tract is constantly exposed to the environment and displays a favorable niche for colonizing microorganisms. However, the effects of respiratory bacterial carriage on the immune system and its implications for secondary responses remain largely unclear. We have employed respiratory carriage with Bordetella bronchiseptica as the underlying model to comprehensively address effects on subsequent immune responses. Carriage was associated with the stimulation of Bordetella-specific CD4⁺, CD8⁺, and CD4⁺CD25⁺Foxp3⁺ T cell responses, and broad transcriptional activation was observed in CD4⁺CD25⁺ T cells. Importantly, transfer of leukocytes from carriers to acutely B. bronchiseptica infected mice, resulted in a significantly increased bacterial burden in the recipient's upper respiratory tract. In contrast, we found that respiratory B. bronchiseptica carriage resulted in a significant benefit for the host in systemic infection with Listeria monocytogenes. Adaptive responses to vaccination and influenza A virus infection, were unaffected by B. bronchiseptica carriage. These data showed that there were significant immune modulatory processes triggered by B. bronchiseptica carriage, that differentially affect subsequent immune responses. Therefore, our results demonstrated the complexity of immune regulation induced by respiratory bacterial carriage, which can be beneficial or detrimental to the host, depending on the pathogen and the considered compartment.

Procalcitonin-Guided Use of Antibiotics for Lower Respiratory Tract Infection

BACKGROUND

The effect of procalcitonin-guided use of antibiotics on treatment for suspected lower respiratory tract infection is unclear.

METHODS

In 14 U.S. hospitals with high adherence to quality measures for the treatment of pneumonia, we provided guidance for clinicians about national clinical practice recommendations for the treatment of lower respiratory tract infections and the interpretation of procalcitonin assays. We then randomly assigned patients who presented to the emergency department with a suspected lower respiratory tract infection and for whom the treating physician was uncertain whether antibiotic therapy was indicated to one of two groups: the procalcitonin group, in which the treating clinicians were provided with real-time initial (and serial, if the patient was hospitalized) procalcitonin assay results and an antibiotic use guideline with graded recommendations based on four tiers of procalcitonin levels, or the usual-care group. We hypothesized that within 30 days after enrollment the total antibiotic-days would be lower - and the percentage of patients with adverse outcomes would not be more than 4.5 percentage points higher - in the procalcitonin group than in the usual-care group.

RESULTS

A total of 1656 patients were included in the final analysis cohort (826 randomly assigned to the procalcitonin group and 830 to the usual-care group), of whom 782 (47.2%) were hospitalized and 984 (59.4%) received antibiotics within 30 days. The treating clinician received procalcitonin assay results for 792 of 826 patients (95.9%) in the procalcitonin group (median time from sample collection to assay result, 77 minutes) and for 18 of 830 patients (2.2%) in the usual-care group. In both groups, the procalcitonin-level tier was associated with the decision to prescribe antibiotics in the emergency department. There was no significant difference between the procalcitonin group and the usual-care group in antibiotic-days (mean, 4.2 and 4.3 days, respectively; difference, -0.05 day; 95% confidence interval [CI], -0.6 to 0.5; P=0.87) or the proportion of patients with adverse outcomes (11.7% [96 patients] and 13.1% [109 patients]; difference, -1.5 percentage points; 95% CI, -4.6 to 1.7; P<0.001 for noninferiority) within 30 days.

CONCLUSIONS

The provision of procalcitonin assay results, along with instructions on their interpretation, to emergency department and hospital-based clinicians did not result in less use of antibiotics than did usual care among patients with suspected lower respiratory tract infection. (Funded by the National Institute of General Medical Sciences; ProACT ClinicalTrials.gov number, NCT02130986 .).

Rivaroxaban for thromboprophylaxis among patients recently hospitalized for acute infectious diseases: a subgroup analysis of the MAGELLAN study

Essentials Net benefit of venous thromboprophylaxis (VTE) in patients hospitalized for infections is unknown. MAGELLAN trial subgroup analysis was performed for patients hospitalized for acute infectious diseases. At day 35, prolonged rivaroxaban prophylaxis reduced VTE compared to enoxaparin (4.2% vs. 6.6%). Rivaroxaban prophylaxis reduced VTE in patients hospitalized for active lung infections.

SUMMARY

Background Despite the well-established association between infection and venous thromboembolism (VTE), there are few data specifically assessing the efficacy and safety of the VTE prophylaxis strategies for patients hospitalized for acute infectious diseases. Objectives To estimate the incidence of VTE and bleeding outcomes, comparing prolonged prophylaxis with rivaroxaban 10 mg daily for 35 days with enoxaparin 40 mg daily for 10 days. Patients/Methods A subgroup analysis of patients hospitalized for acute infectious diseases in the MAGELLAN trial was performed. The primary efficacy outcome was the composite of asymptomatic proximal or symptomatic VTE at days 10 and 35. The principal safety outcome was the composite of major or clinically relevant non-major bleeding. Results Three thousand one hundred and seventy-three patients with acute infectious diseases leading to hospitalization were randomized to either rivaroxaban (n = 1585) or enoxaparin/placebo (n = 1588), and received at least one dose of study medication. At day 10, primary composite efficacy outcomes did not differ between prophylaxis strategies (rivaroxaban, 2.7%; and enoxaparin, 3.7%). At day 35, there were fewer VTE events with rivaroxaban (4.2%) than with enoxaparin (6.6%) (relative risk [RR] 0.64; 95% confidence interval [CI] 0.45-0.92). Patients with pulmonary infections randomized to rivaroxaban had a lower incidence of VTE both at 10 days (RR 0.50, 95% CI 0.28-0.90) and at 35 days (RR 0.54, 95% CI 0.33-0.87). Primary safety outcome events were increased with rivaroxaban (RR 2.42, 95% CI 1.60-3.66). Conclusions Prolonged rivaroxaban prophylaxis reduced the incidence of VTE in patients hospitalized for acute infectious diseases, particularly those involving the lungs. Efficacy benefits were, in part, offset by bleeding outcomes. ClinicalTrials.gov Number: NCT 00571649.

Laboratory diagnosis of Mycoplasma pneumoniae infections: data analysis from clinical practice

An etiological diagnosis of respiratory infections caused by Mycoplasma pneumoniae is particularly challenging due to the lack of a definite standard test. This study aimed to analyse the correlation and combination of diagnostic results obtained from direct and indirect assays (Mycoplasma pneumoniae DNA by PCR and serology) in use at a first level diagnostic laboratory. Samples from patients with respiratory infections tested for M. pneumoniae during routine clinical practice were retrospectively analysed. In pediatric patients <15 years old, we documented a significantly higher proportion of IgM positive results (23.6% versus 3.9% in ≥15-year-old patients, p<0.0001) but a lower IgM specificity (false positive IgM 34.8% versus 12.2% in ≥15 years old patients, p 0.01), as verified by seroconversion. A small percentage (4%) of respiratory samples were positive for M. pneumoniae DNA regardless of age and type of sample. Assuming IgM positivity as the reference standard, PCR showed a total lack of sensitivity in patients <15 years old and 20% sensitivity in children <15 years old; specificity was 95% in both age groups. Agreement between PCR and IgM serology was slight (Cohen's kappa 0.09). According to our data, no single diagnostic test could be considered optimal for M. pneumoniae detection and improved assays are required.

Cytokine kinetic profiles in children with acute lower respiratory tract infection: a post hoc descriptive analysis from a randomized control trial

OBJECTIVES

Standard inflammatory markers and chest radiography lack the ability to discriminate bacterial from non-bacterial lower respiratory tract infection (LRTI). Cytokine profiles may serve as biomarkers for LRTI, but their applicability to identify aetiology, severity of disease and need for antibiotic prescription in children remains poorly defined. Objectives were to determine the cytokine kinetic profiles over 5 days in paediatric patients with LRTI, to investigate the relationship between cytokine patterns, and clinical and laboratory variables.

METHODS

We included patients aged 1 month to 18 years, with febrile LRTI and three consecutive cytokines measurements on days 1, 3 and 5 of a randomized controlled trial (ProPAED study). We evaluated differences in cytokine concentrations between days and associations with clinical and laboratory variables.

RESULTS

A total of 181 patients (median age 4.1 years) were included; 72/181 (40%) received antibiotics. Serum concentrations of interferon (IFN)-γ, interleukin (IL)-1ra, IL-6, IL-10, IFN-γ-inducible protein (IP)-10 and tumor necrosis factor-α were elevated on day 1 and decreased subsequently, with the greatest decline between day 1 and 3 (by -8 to >-94%). Procalcitonin (PCT) and C-reactive protein (CRP) values showed a protracted decrease with the most prominent reduction in concentrations between days 3 and 5. Significantly elevated IL-6 concentrations were associated with hospital admission, antibiotic treatment, and prolonged antibiotic treatment. Bacteraemic LRTI patients had higher concentrations of IL-1ra (p <0.0055) and IL-6 (p <0.0055) on day 1.

CONCLUSIONS

We observed an earlier decrease of elevated cytokines compared to PCT or CRP. Both pro- and anti-inflammatory cytokines may serve as markers for severity of LRTI.

Procalcitonin Testing to Guide Antibiotic Therapy in Acute Upper and Lower Respiratory Tract Infections

CLINICAL QUESTION

Is the use of procalcitonin for guiding antibiotic decisions in patients with acute upper and lower respiratory tract infections associated with improved clinical outcomes compared with usual care?

BOTTOM LINE

Among patients with varying types and severity of acute respiratory infection, using procalcitonin to guide decisions about antibiotics is associated with lower rates of antibiotic exposure, antibiotic-related adverse effects, and mortality.

Lethal murine infection model for human respiratory disease-associated Pteropine orthoreovirus

Pteropine orthoreovirus (PRV) is an emerging bat-borne human pathogen causing severe respiratory illness. To date, however, the evaluation of PRV virulence has largely depended on the limited numbers of clinical cases owing to the lack of animal models. To develop an in vivo model of PRV infection, an inbred C3H mouse strain was infected intranasally with pathogenic PRV strain Miyazaki-Bali/2007. C3H mice suffered severe lung infection with significant body weight reduction and died within 7 days after intranasal infection. Infectious viruses were isolated mainly from the lungs and trachea. Histopathological examination revealed interstitial pneumonia with monocytes infiltration. Following repeated intranasal infection, mice developed antibodies to particular structural and non-structural proteins of PRV. The results of these immunological assays will help to develop laboratory protocols for sero-epidemiological studies. Our small rodent model of lethal respiratory infection will further allow investigation of the molecular mechanisms underlying the high pathogenicity of PRV.

•

A lethal PRV strain Miyazaki-Bali/2007 murine infection model was established.

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Susceptibility of different mouse strains to PRV infection was investigated.

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Antibody responses to PRV proteins in C3H mice post intranasal infection were studied.

The Coincidence of Newly Diagnosed Type 1 Diabetes Mellitus with IgM Antibody Positivity to Enteroviruses and Respiratory Tract Viruses

OBJECTIVE

Viruses trigger and promote islet cell destruction and cause type 1 diabetes mellitus (T1DM). However, the existence of a cause-and-effect relationship is under debate. The aim of this study is to investigate the sero-epidemiological and molecular evidence on enteroviruses and respiratory viruses in patients with newly diagnosed T1DM during the cold season.

DESIGN

Forty children newly diagnosed with T1DM and 30 healthy children who presented to the clinic over the course of a year were included in the study. The IgM antibodies against enteroviruses and respiratory viruses were studied using the indirect immunofluorescence assay (IFA) test, and no CBV4-specific RNA was detected in the children. The onset times of T1DM were classified into fall-winter and spring-summer seasons and separated into cold, moderate, or warm months in terms of temperature.

RESULTS

The percentages of viral IgM antibodies against most common viruses were detected in the patients as follows: influenza B (IVB) (70%), echovirus 7 (ECHO7) (45%), parainfluenza virus 4 (PIV4) (40%), coxsackievirus A7 (CAV7) (27.5%), and H3N2 (22.5%). Compared with the control group, the above viruses had a significant association with T1DM (p ≤ 0.001, p ≤ 0.001, p = 0.035, p = 0.003, and p = 0.023, resp.). CBV4-specific RNA was not detected in any serum. A total of 75% and 95% patients were diagnosed with T1DM in the fall-winter seasons and cold-moderate months, respectively.

CONCLUSION

Our study demonstrates the significant association between T1DM and the presence of IgM antibodies against IVB, ECHO7, PIV4, CAV7, and H3N2, and the majority of newly diagnosed T1DM appeared in the fall-winter season. It suggests that enteroviruses and respiratory viruses, in addition to seasonal variation, could play a role in the etiopathogenesis and clinical onset of T1DM.

Serum 25-hydroxyvitamin D levels in patients with Granulomatosis with Polyangiitis: association with respiratory infection

OBJECTIVES

To determine the possible association of serum 25-hydroxyvitamin D (25OHD) levels with disease activity and respiratory infection in granulomatosis with polyangiitis patients during two different periods: winter/spring and summer/autumn.

METHODS

Thirty-two granulomatosis with polyangiitis patients were evaluated in the winter/spring, and the same patients (except 5) were evaluated in summer/autumn (n=27). The 25OHD levels were measured by radioimmunoassay. Disease activity was assessed by the Birmingham Vasculitis Activity Score Modified for Wegener's Granulomatosis (BVAS/WG) and antineutrophil cytoplasmic antibody (ANCA) positivity. Respiratory infection was defined according the Centers for Disease Control and Prevention criteria.

RESULTS

25OHD levels were lower among patients in winter/spring than in summer/autumn (32.31±13.10 vs. 38.98±10.97 ng/mL, p=0.04). Seven patients met the criteria for respiratory infection: 5 in winter/spring and 2 in summer/autumn. Patients with respiratory infection presented lower 25OHD levels than those without infection (25.15±11.70 vs. 36.73±12.08 ng/mL, p=0.02). A higher frequency of low vitamin D levels (25OHD<20 ng/mL) was observed in patients with respiratory infection (37.5% vs. 7.8, p=0.04). Serum 25OHD levels were comparable between patients with (BVAS/WG≥1 plus positive ANCA) and without disease activity (BVAS/WG=0 plus negative ANCA) (35.40±11.48 vs. 35.34±13.13 ng/mL, p=0.98).

CONCLUSIONS

Lower 25OHD levels were associated with respiratory infection but not disease activity in granulomatosis with polyangiitis patients. Our data suggest that hypovitaminosis D could be an important risk factor for respiratory infection in granulomatosis with polyangiitis patients.

Procalcitonin to initiate or discontinue antibiotics in acute respiratory tract infections

BACKGROUND

Acute respiratory infections (ARIs) comprise of a large and heterogeneous group of infections including bacterial, viral, and other aetiologies. In recent years, procalcitonin (PCT), a blood marker for bacterial infections, has emerged as a promising tool to improve decisions about antibiotic therapy (PCT-guided antibiotic therapy). Several randomised controlled trials (RCTs) have demonstrated the feasibility of using procalcitonin for starting and stopping antibiotics in different patient populations with ARIs and different settings ranging from primary care settings to emergency departments, hospital wards, and intensive care units. However, the effect of using procalcitonin on clinical outcomes is unclear. This is an update of a Cochrane review and individual participant data meta-analysis first published in 2012 designed to look at the safety of PCT-guided antibiotic stewardship.

OBJECTIVES

The aim of this systematic review based on individual participant data was to assess the safety and efficacy of using procalcitonin for starting or stopping antibiotics over a large range of patients with varying severity of ARIs and from different clinical settings.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Acute Respiratory Infections Group's Specialised Register, MEDLINE, and Embase, in February 2017, to identify suitable trials. We also searched ClinicalTrials.gov to identify ongoing trials in April 2017.

SELECTION CRITERIA

We included RCTs of adult participants with ARIs who received an antibiotic treatment either based on a procalcitonin algorithm (PCT-guided antibiotic stewardship algorithm) or usual care. We excluded trials if they focused exclusively on children or used procalcitonin for a purpose other than to guide initiation and duration of antibiotic treatment.

DATA COLLECTION AND ANALYSIS

Two teams of review authors independently evaluated the methodology and extracted data from primary studies. The primary endpoints were all-cause mortality and treatment failure at 30 days, for which definitions were harmonised among trials. Secondary endpoints were antibiotic use, antibiotic-related side effects, and length of hospital stay. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) using multivariable hierarchical logistic regression adjusted for age, gender, and clinical diagnosis using a fixed-effect model. The different trials were added as random-effects into the model. We conducted sensitivity analyses stratified by clinical setting and type of ARI. We also performed an aggregate data meta-analysis.

MAIN RESULTS

From 32 eligible RCTs including 18 new trials for this 2017 update, we obtained individual participant data from 26 trials including 6708 participants, which we included in the main individual participant data meta-analysis. We did not obtain individual participant data for four trials, and two trials did not include people with confirmed ARIs. According to GRADE, the quality of the evidence was high for the outcomes mortality and antibiotic exposure, and quality was moderate for the outcomes treatment failure and antibiotic-related side effects.Primary endpoints: there were 286 deaths in 3336 procalcitonin-guided participants (8.6%) compared to 336 in 3372 controls (10.0%), resulting in a significantly lower mortality associated with procalcitonin-guided therapy (adjusted OR 0.83, 95% CI 0.70 to 0.99, P = 0.037). We could not estimate mortality in primary care trials because only one death was reported in a control group participant. Treatment failure was not significantly lower in procalcitonin-guided participants (23.0% versus 24.9% in the control group, adjusted OR 0.90, 95% CI 0.80 to 1.01, P = 0.068). Results were similar among subgroups by clinical setting and type of respiratory infection, with no evidence for effect modification (P for interaction > 0.05). Secondary endpoints: procalcitonin guidance was associated with a 2.4-day reduction in antibiotic exposure (5.7 versus 8.1 days, 95% CI -2.71 to -2.15, P < 0.001) and lower risk of antibiotic-related side effects (16.3% versus 22.1%, adjusted OR 0.68, 95% CI 0.57 to 0.82, P < 0.001). Length of hospital stay and intensive care unit stay were similar in both groups. A sensitivity aggregate-data analysis based on all 32 eligible trials showed similar results.

AUTHORS' CONCLUSIONS

This updated meta-analysis of individual participant data from 12 countries shows that the use of procalcitonin to guide initiation and duration of antibiotic treatment results in lower risks of mortality, lower antibiotic consumption, and lower risk for antibiotic-related side effects. Results were similar for different clinical settings and types of ARIs, thus supporting the use of procalcitonin in the context of antibiotic stewardship in people with ARIs. Future high-quality research is needed to confirm the results in immunosuppressed patients and patients with non-respiratory infections.

Seasonal variations of U.S. mortality rates: Roles of solar ultraviolet-B doses, vitamin D, gene exp ression, and infections

Death rates in the U.S. show a pronounced seasonality. The broad seasonal variation shows about 25% higher death rates in winter than in summer with an additional few percent increase associated with the Christmas and New Year's holidays. A pronounced increase in death rates also starts in mid-September, shortly after the school year begins. The causes of death with large contributions to the observed seasonality include diseases of the circulatory system; the respiratory system; the digestive system; and endocrine, nutritional, and metabolic diseases. Researchers have identified several factors showing seasonal variation that could possibly explain the seasonal variations in mortality rate. These factors include seasonal variations in solar ultraviolet-B(UVB) doses and serum 25-hydroxyvitamin D [25(OH)D] concentrations, gene expression, ambient temperature and humidity, UVB effects on environmental pathogen load, environmental pollutants and allergens, and photoperiod (or length of day). The factors with the strongest support in this analysis are seasonal variations in solar UVB doses and 25(OH)D concentrations. In the U.S., population mean 25(OH)D concentrations range from 21ng/mL in March to 28ng/mL in August. Measures to ensure that all people had 25(OH)D concentrations >36ng/mL year round would probably reduce death rates significantly.

Clinician-targeted interventions to influence antibiotic prescribing behaviour for acute respiratory infections in primary care: an overview of systematic reviews

BACKGROUND

Antibiotic resistance is a worldwide health threat. Interventions that reduce antibiotic prescribing by clinicians are expected to reduce antibiotic resistance. Disparate interventions to change antibiotic prescribing behaviour for acute respiratory infections (ARIs) have been trialled and meta-analysed, but not yet synthesised in an overview. This overview synthesises evidence from systematic reviews, rather than individual trials.

OBJECTIVES

To systematically review the existing evidence from systematic reviews on the effects of interventions aimed at influencing clinician antibiotic prescribing behaviour for ARIs in primary care.

METHODS

We searched the Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects (DARE), MEDLINE, Embase, CINAHL, PsycINFO, and Science Citation Index to June 2016. We also searched the reference lists of all included reviews. We ran a pre-publication search in May 2017 and placed additional studies in 'awaiting classification'.We included both Cochrane and non-Cochrane reviews of randomised controlled trials evaluating the effect of any clinician-focussed intervention on antibiotic prescribing behaviour in primary care. Two overview authors independently extracted data and assessed the methodological quality of included reviews using the ROBIS tool, with disagreements reached by consensus or by discussion with a third overview author. We used the GRADE system to assess the quality of evidence in included reviews. The results are presented as a narrative overview.

MAIN RESULTS

We included eight reviews in this overview: five Cochrane Reviews (33 included trials) and three non-Cochrane reviews (11 included trials). Three reviews (all Cochrane Reviews) scored low risk across all the ROBIS domains in Phase 2 and low risk of bias overall. The remaining five reviews scored high risk on Domain 4 of Phase 2 because the 'Risk of bias' assessment had not been specifically considered and discussed in the review Results and Conclusions. The trials included in the reviews varied in both size and risk of bias. Interventions were compared to usual care.Moderate-quality evidence indicated that C-reactive protein (CRP) point-of-care testing (risk ratio (RR) 0.78, 95% confidence interval (CI) 0.66 to 0.92, 3284 participants, 6 trials), shared decision making (odds ratio (OR) 0.44, 95% CI 0.26 to 0.75, 3274 participants, 3 trials; RR 0.64, 95% CI 0.49 to 0.84, 4623 participants, 2 trials; risk difference -18.44, 95% CI -27.24 to -9.65, 481,807 participants, 4 trials), and procalcitonin-guided management (adjusted OR 0.10, 95% CI 0.07 to 0.14, 1008 participants, 2 trials) probably reduce antibiotic prescribing in general practice. We found moderate-quality evidence that procalcitonin-guided management probably reduces antibiotic prescribing in emergency departments (adjusted OR 0.34, 95% CI 0.28 to 0.43, 2605 participants, 7 trials). The overall effect of these interventions was small (few achieving greater than 50% reduction in antibiotic prescribing, most about a quarter or less), but likely to be clinically important.Compared to usual care, shared decision making probably makes little or no difference to reconsultation for the same illness (RR 0.87, 95% CI 0.74 to 1.03, 1860 participants, 4 trials, moderate-quality evidence), and may make little or no difference to patient satisfaction (RR 0.86, 95% CI 0.57 to 1.30, 1110 participants, 2 trials, low-quality evidence). Similarly, CRP testing probably has little or no effect on patient satisfaction (RR 0.79, 95% CI 0.57 to 1.08, 689 participants, 2 trials, moderate-quality evidence) or reconsultation (RR 1.08, 95% CI 0.93 to 1.27, 5132 participants, 4 trials, moderate-quality evidence). Procalcitonin-guided management probably results in little or no difference in treatment failure in general practice compared to normal care (adjusted OR 0.95, 95% CI 0.73 to 1.24, 1008 participants, 2 trials, moderate-quality evidence), however it probably reduces treatment failure in the emergency department compared to usual care (adjusted OR 0.76, 95% CI 0.61 to 0.95, 2605 participants, 7 trials, moderate-quality evidence).The quality of evidence for interventions focused on clinician educational materials and decision support in reducing antibiotic prescribing in general practice was either low or very low (no pooled result reported) and trial results were highly heterogeneous, therefore we were unable draw conclusions about the effects of these interventions. The use of rapid viral diagnostics in emergency departments may have little or no effect on antibiotic prescribing (RR 0.86, 95% CI 0.61 to 1.22, 891 participants, 3 trials, low-quality evidence) and may result in little to no difference in reconsultation (RR 0.86, 95% CI 0.59 to 1.25, 200 participants, 1 trial, low-quality evidence).None of the trials in the included reviews reported on management costs for the treatment of an ARI or any associated complications.

AUTHORS' CONCLUSIONS

We found evidence that CRP testing, shared decision making, and procalcitonin-guided management reduce antibiotic prescribing for patients with ARIs in primary care. These interventions may therefore reduce overall antibiotic consumption and consequently antibiotic resistance. There do not appear to be negative effects of these interventions on the outcomes of patient satisfaction and reconsultation, although there was limited measurement of these outcomes in the trials. This should be rectified in future trials.We could gather no information about the costs of management, and this along with the paucity of measurements meant that it was difficult to weigh the benefits and costs of implementing these interventions in practice.Most of this research was undertaken in high-income countries, and it may not generalise to other settings. The quality of evidence for the interventions of educational materials and tools for patients and clinicians was either low or very low, which prevented us from drawing any conclusions. High-quality trials are needed to further investigate these interventions.

Prospective observational study in two Dutch hospitals to assess the performance of inflammatory plasma markers to determine disease severity of viral respiratory tract infections in children

INTRODUCTION

Respiratory viruses causing lower respiratory tract infections (LRTIs) are a major cause of hospital admissions in children. Since the course of these infections is unpredictable with potential fast deterioration into respiratory failure, infants are easily admitted to the hospital for observation. The aim of this study was to examine whether systemic inflammatory markers can be used to predict severity of disease in children with respiratory viral infections.

METHODS

Blood and nasopharyngeal washings from children <3 years of age with viral LRTI attending a hospital were collected within 24 hours (acute) and after 4-6 weeks (recovery). Patients were assigned to a mild (observation only), moderate (supplemental oxygen and/or nasogastric feeding) or severe (mechanical ventilation) group. Linear regression analysis was used to design a prediction rule using plasma levels of C reactive protein (CRP), serum amyloid A (SAA), pentraxin 3 (PTX3), serum amyloid P component and properdin. This rule was tested in a validation cohort.

RESULTS

One hundred and four children (52% male) were included. A combination of CRP, SAA, PTX3 and properdin was a better indicator of severe disease compared with any of the individual makers and age (69% sensitivity (95% CI 50 to 83), 90% specificity (95% CI 80 to 96)). Validation in 141 patients resulted in 71% sensitivity (95% CI 53 to 85), 87% specificity (95% CI 79 to 92), negative predictive value of 64% (95% CI 47 to 78) and positive predictive value of 90% (95% CI 82 to 95). The prediction rule was not able to identify patients with a mild course of disease.

CONCLUSION

A combination of CRP, SAA, PTX3 and properdin was able to identify children with a severe course of viral LRTI disease, even in children under 2 months of age. To assess the true impact on clinical management, these results should be validated in a prospective randomised control study.

Recurrent respiratory tract infections (RRTI) in the elderly: A late onset mild immunodeficiency?

Elderly with late-onset recurrent respiratory tract infections (RRTI) often have specific anti-polysaccharide antibody deficiency (SPAD). We hypothesized that late-onset RRTI is caused by mild immunodeficiencies, such as SPAD, that remain hidden through adult life. We analyzed seventeen elderly RRTI patients and matched controls. We determined lymphocyte subsets, expression of BAFF receptors, serum immunoglobulins, complement pathways, Pneumovax-23 vaccination response and genetic variations in BAFFR and MBL2. Twelve patients (71%) and ten controls (59%) had SPAD. IgA was lower in patients than in controls, but other parameters did not differ. However, a high percentage of both patients (53%) and controls (65%) were MBL deficient, much more than in the general population. Often, MBL2 secretor genotypes did not match functional deficiency, suggesting that functional MBL deficiency can be an acquired condition. In conclusion, we found SPAD and MBL deficiency in many elderly, and conjecture that at least the latter arises with age.

Low cord-serum 25-hydroxyvitamin D levels are associated with poor lung function performance and increased respiratory infection in infancy

Background

Perinatal vitamin D deficiency is associated with a higher risk of wheezing in childhood. However, the relationship between vitamin D levels and lung function in infancy has not been investigated. The aim of this study was to investigate the impact of perinatal vitamin D levels on respiratory function and disease outcome in infancy.

Materials and methods

Full-term infants without any chronic diseases or major anomalies were enrolled in the Prediction of Allergies in Taiwanese Children cohort study. Maternal and cord blood were collected for determining the 25(OH)D level. Questionnaires were recorded at birth and 6 months of age. Infant lung function, including tidal breathing analysis, respiratory mechanics, and forced tidal expiration, was tested at 6 months of age.

Results

A total of 122 mother—infant pairs were enrolled in this study, and 71 infants underwent lung function testing at 6 months of age. 25(OH)D levels in maternal and cord serum were highly correlated (r² = 0.457, p < 0.0001). Infants with lower cord serum 25(OH)D levels (< 13.7 ng/ml) had higher resistance of respiratory system (p < 0.01) and a higher risk of a respiratory tract infection before the age of 6 months (p < 0.01).

Conclusion

Although a high correlation was found between maternal and cord vitamin D levels, the effect on respiratory outcome was different. Our study is the first to show that low cord 25(OH)D levels significantly relationship with poorer lung function performance and higher likelihood of a respiratory tract infection before 6 months of age.

The relationship of serum vitamins A, D, E and LL-37 levels with allergic status, tonsillar virus detection and immune response

Background

Tonsils have an active role in immune defence and inducing and maintaining tolerance to allergens. Vitamins A, D, and E, and antimicrobial peptide LL-37 may have immunomodulatory effects. We studied how their serum levels were associated with allergy status, intratonsillar/nasopharyngeal virus detection and intratonsillar expression of T cell- and innate immune response-specific cytokines, transcription factors and type I/II/III interferons in patients undergoing tonsillectomy.

Methods

110 elective tonsillectomy patients participated. Serum levels of vitamins A, 25(OH)D, and E, LL-37 and allergen-specific IgE as well as nasopharyngeal/intratonsillar respiratory viruses were analyzed. The mRNA expression of IFN-α, IFN-β, IFN-γ, IL-10, IL-13, IL-17, IL-28, IL-29, IL-37, TGF-β, FOXP3, GATA3, RORC2 and Tbet in tonsils were analyzed by quantitative RT-PCR.

Results

The median age of the patients was 16 years (range 3–60), 28% of subjects had atopy, and 57% carried ≥1 respiratory virus in nasopharynx. Detection of viruses decreased by age. Higher vitamin A levels showed borderline significance with less viral detection (P = 0.056). Higher 25(OH)D was associated with less allergic rhinitis and atopy (P < 0.05) and higher vitamin E with less self-reported allergy (P < 0.05). In gene expression analyses, 25(OH)D was associated with higher IL-37, vitamin A with higher IFN-γ and vitamin E with less IL-28 (P < 0.05). LL-37 was associated with less FOXP3, RORC2 and IL-17 in tonsils (P < 0.05).

Conclusions

Vitamin D and E levels were associated with less allergic disorders. Vitamin A was linked to antiviral and vitamin D with anti-inflammatory activity. LL-37 and was linked to T regulatory cell effects.