Procalcitonin and C-reactive protein in severe 2009 H1N1 influenza infection

Latest developments in early diagnosis and specific treatment of severe influenza infection

Influenza pandemics are unpredictable recurrent events with global health, economic, and social consequences. The objective of this review is to provide an update on the latest developments in early diagnosis and specific treatment of the disease and its complications, particularly with regard to respiratory organ failure. Despite advances in treatment, the rate of mortality in the intensive care unit remains approximately 30%. Therefore, early identification of potentially severe viral pneumonia is extremely important to optimize treatment in these patients. The pathogenesis of influenza virus infection depends on viral virulence and host response. Thus, in some patients, it is associated with an excessive systemic response mediated by an authentic cytokine storm. This process leads to severe primary pneumonia and acute respiratory distress syndrome. Initial prognostication in the emergency department based on comorbidities, vital signs, and biomarkers (e.g., procalcitonin, ferritin, human leukocyte antigen-DR, mid-regional proadrenomedullin, and lactate) is important. Identification of these biomarkers on admission may facilitate clinical decision-making to determine early admission to the hospital or the intensive care unit. These decisions are reached considering pathophysiological circumstances that are associated with a poor prognosis (e.g., bacterial co-infection, hyperinflammation, immune paralysis, severe endothelial damage, organ dysfunction, and septic shock). Moreover, early implementation is important to increase treatment efficacy. Based on a limited level of evidence, all current guidelines recommend using oseltamivir in this setting. The possibility of drug resistance should also be considered. Alternative options include other antiviral drugs and combination therapies with monoclonal antibodies. Importantly, it is not recommended to use corticosteroids in the initial treatment of these patients. Furthermore, the implementation of supportive measures for respiratory failure is essential. Current recommendations are limited, heterogeneous, and not regularly updated. Early intubation and mechanical ventilation is the basic treatment for patients with severe respiratory failure. Prone ventilation should be promptly performed in patients with acute respiratory distress syndrome, while early tracheostomy should be considered in case of planned prolonged mechanical ventilation. Clinical trials on antiviral treatment and respiratory support measures specifically for these patients, as well as specific recommendations for different at-risk populations, are necessary to improve outcomes.

Plasma levels of neurogenic inflammation related neuropeptides in pediatric patients with community-acquired pneumonia and their potential diagnostic value in distinguishing viral and bacterial pneumonia

Neurogenic inflammation is involved in the development and progression of respiratory inflammatory diseases. However, its role in community-acquired pneumonia (CAP) remains unclear. We therefore aimed to investigate plasma levels of neurogenic inflammation-related neuropeptides, calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY), and procalcitonin (PCT) in pediatric patients with CAP and to assess their diagnostic value in viral and bacterial/mixed pneumonia. A total of 124 pediatric patients with CAP (1 month-18 years old) and 56 healthy children of similar ages were prospectively enrolled. The patients were classified as viral (n = 99) and bacterial/mixed (n = 25) pneumonia. Plasma levels of the peptides were quantified by ELISA. ROC analysis was performed to evaluate possible diagnostic value of the peptides. While plasma levels of CGRP, VIP and PCT were significantly higher in patients with CAP than in the control group, respectively, NPY levels were significantly lower. Moreover, plasma levels of all neuropeptides and PCT were significantly higher in bacterial pneumonia patients compared to viral pneumonia patients. ROC analysis revealed that CGRP, SP and NPY had a diagnostic value in distinguishing viral and bacterial/mixed pneumonia.

CONCLUSIONS

Our findings suggest that these neuropeptides may be implicated in pediatric CAP. CGRP, SP and NPY together may be a promising candidate in distinguishing viral and bacterial/mixed pneumonia, however, for this, further studies are needed.

WHAT IS KNOWN

• Neurogenic inflammation contributes to the development and progression of respiratory inflammatory diseases such as chronic obstructive pulmonary disease and bronchial asthma.

WHAT IS NEW

• Plasma levels of neurogenic inflammation related neuropeptides calcitonin gene-related peptide, substance P, vasoactive intestinal peptide and neuropeptide Y are changed in pediatric community-acquired pneumonia. Calcitonin gene-related peptide, substance P and neuropeptide Y are promising candidates in distinguishing viral and bacterial/mixed pneumonia.

Procalcitonin and C-reactive protein to rule out early bacterial coinfection in COVID-19 critically ill patients

PURPOSE

Although the prevalence of community-acquired respiratory bacterial coinfection upon hospital admission in patients with coronavirus disease 2019 (COVID-19) has been reported to be < 5%, almost three-quarters of patients received antibiotics. We aim to investigate whether procalcitonin (PCT) or C-reactive protein (CRP) upon admission could be helpful biomarkers to identify bacterial coinfection among patients with COVID-19 pneumonia.

METHODS

We carried out a multicentre, observational cohort study including consecutive COVID-19 patients admitted to 55 Spanish intensive care units (ICUs). The primary outcome was to explore whether PCT or CRP serum levels upon hospital admission could predict bacterial coinfection among patients with COVID-19 pneumonia. The secondary outcome was the evaluation of their association with mortality. We also conducted subgroups analyses in higher risk profile populations.

RESULTS

Between 5 February 2020 and 21 December 2021, 4076 patients were included, 133 (3%) of whom presented bacterial coinfection. PCT and CRP had low area under curve (AUC) scores at the receiver operating characteristic (ROC) curve analysis [0.57 (95% confidence interval (CI) 0.51-0.61) and 0.6 (95% CI, 0.55-0.64), respectively], but high negative predictive values (NPV) [97.5% (95% CI 96.5-98.5) and 98.2% (95% CI 97.5-98.9) for PCT and CRP, respectively]. CRP alone was associated with bacterial coinfection (OR 2, 95% CI 1.25-3.19; p = 0.004). The overall 15, 30 and 90 days mortality had a higher trend in the bacterial coinfection group, but without significant difference. PCT ≥ 0.12 ng/mL was associated with higher 90 days mortality.

CONCLUSION

Our study suggests that measurements of PCT and CRP, alone and at a single time point, are not useful for ruling in or out bacterial coinfection in viral pneumonia by COVID-19.

How to use biomarkers of infection or sepsis at the bedside: guide to clinicians

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. In this context, biomarkers could be considered as indicators of either infection or dysregulated host response or response to treatment and/or aid clinicians to prognosticate patient risk. More than 250 biomarkers have been identified and evaluated over the last few decades, but no biomarker accurately differentiates between sepsis and sepsis-like syndrome. Published data support the use of biomarkers for pathogen identification, clinical diagnosis, and optimization of antibiotic treatment. In this narrative review, we highlight how clinicians could improve the use of pathogen-specific and of the most used host-response biomarkers, procalcitonin and C-reactive protein, to improve the clinical care of patients with sepsis. Biomarker kinetics are more useful than single values in predicting sepsis, when making the diagnosis and assessing the response to antibiotic therapy. Finally, integrated biomarker-guided algorithms may hold promise to improve both the diagnosis and prognosis of sepsis. Herein, we provide current data on the clinical utility of pathogen-specific and host-response biomarkers, offer guidance on how to optimize their use, and propose the needs for future research.

Low Levels of Procalcitonin Are Related to Decreased Antibiotic Use in Children Hospitalized Due to Influenza

Procalcitonin increases in bacterial infections, which are often suspected (though rarely confirmed) in paediatric influenza. We retrospectively verified procalcitonin’s usefulness in antibiotic guidance in children hospitalized due to laboratory-confirmed influenza. The ROC curve analysis evaluated procalcitonin’s performance in terms of antibiotic implementation or continuation in patients who were naive or had been receiving antibiotic treatment prior to hospital admission. We also assessed the procalcitonin’s usefulness to predict lower-respiratory-tract infections (LRTI), the presence of radiologically confirmed pneumonia, an intensive care unit transfer and a fatal outcome. Multiple regression models were built to verify the previously reported procalcitonin cut-off values. The study enrolled 371 children (median age 33 months). The AUC (area under the curve) for antibiotic implementation reached 0.66 (95%CI: 0.58–0.73) and 0.713 (95%CI: 0.6–0.83) for antibiotic continuation; optimal cut-offs (0.4 and 0.23 ng/mL, respectively) resulted in a negative predictive value (NPV) of 79.7% (95%CI: 76.2–82.9%) and 54.6% (95%CI: 45.8–63%), respectively. The use of 0.25 ng/mL as a reference decreased the odds of antibiotic treatment by 67% (95%CI: 43–81%) and 91% (95%CI: 56–98%), respectively. Procalcitonin showed lower AUC for the prediction of LRTI and pneumonia (0.6, 95%CI: 0.53–0.66, and 0.63, 95%CI: 0.56–0.7, respectively), with a moderately high NPV in the latter case (83%, 95%CI: 79.3–86.1%). Procalcitonin use may decrease the antibiotic frequency in hospitalized influenza cases both in terms of antibiotic administration and continuation. Procalcitonin concentrations may suggest bacterial suprainfections at lower concentrations than in adults, and a focus on its rule-out value is of special interest.

Plasma Levels of Mid-Regional Proadrenomedullin Accurately Identify H1N1pdm09 Influenza Virus Patients with Risk of Intensive Care Admission and Mortality in the Emergency Department

Early identification of severe viral pneumonia in influenza virus A (H1N1pdm09) patients is extremely important for prompt admission to the ICU. The objective is to evaluate the usefulness of MR-proadrenomedullin (MR-proADM) compared to C reactive protein (CRP), procalcitonin (PCT), and ferritin in the prognosis of influenza A pneumonia. This prospective, observational, multicenter study included one hundred thirteen patients with confirmed influenza virus A (H1N1pdm09) admitted to an Emergency Department and ICUs of six hospitals in Spain. Measurements and Main Results: one-hundred thirteen patients with confirmed influenza virus A (H1N1pdm09) were enrolled. Seventy-five subjects (mortality 29.3%) with severe pneumonia caused by influenza A H1N1pdm09 virus (H1N1vIPN) were compared with 38 controls (CG).The median MR-proADM levels at hospital admission were 1.2 nmol/L (IQR (0.8–2.6) vs. 0.5 nmol/L (IQR 0.2–0.9) in the CG (p = 0.01), and PCT levels were 0.43 μg/L (IQR 0.2–1.2) in the H1N1vIPN group and 0.1 μg/L (IQR 0.1–0.2) in the CG (p < 0.01). CRP levels at admission were 15.5 mg/dL(IQR 9.2–24.9) in H1N1vIPN and 8.6 mg/dL(IQR 3–17.3) in the CG (p < 0.01). Ferritin levels at admission were 558.1 ng/mL(IQR 180–1880) in H1N1vIPN and 167.7 ng/mL(IQR 34.8–292.9) in the CG (p < 0.01). A breakpoint for hospital admission of MR-proADM of 1.1 nmol/L showed a sensitivity of 55% and a specificity of 90% (AUC-ROC0.822). Non-survivors showed higher MR-proADM levels: median of 2.5 nmol/L vs. 0.9 nmol/L among survivors (p < 0.01). PCT, CRP, and ferritin levels also showed significant differences in predicting mortality. The MR-proADM AUC-ROC for mortality was 0.853 (p < 0.01). In a Cox proportional hazards model, MR-proADM levels > 1.2 nmol/L at hospital admission were significant predictive factors for ICU and 90-day mortality (HR: 1.3). Conclusions: the initial MR-proADM, ferritin, CRP, and PCT levels effectively determine adverse outcomes and risk of ICU admission and mortality in patients with influenza virus pneumonia. MR-proADM has the highest potency for survival prediction.

Clinical characteristics and outcomes in hospitalized adult influenza patients: an observational study from Norway 2014-2018

BACKGROUND

Seasonal influenza causes substantial numbers of hospitalizations annually. We have characterized the clinical picture and treatment practice in hospitalized adult influenza patients and assessed whether clinical risk scores on admission or influenza type were associated with severe outcomes.

METHODS

Clinical characteristics and risk scores on admission (CRB65, CRB, SIRS and quick Sequential Organ Failure Assessment [qSOFA]), treatment and severe outcomes (defined as: stay in intensive care unit (ICU), receiving oxygen supplementation or staying ≥5 days in hospital), were recorded in patients hospitalized with influenza at Oslo University Hospital, Norway, between 2014 and 2018.

RESULTS

Among the 156 included patients, 52.6% had influenza A(H3N2), 32.6% influenza B and 12.8% influenza A(H1N1). Median age was 70 years and 59.6% of patients were ≥65 years. Nine (5.8%) of the patients were treated in ICU, 43.0% received oxygen and 47.4% stayed ≥5 days in hospital. Overall, 34.6% of the patients had a high CRB score on admission which was associated with stay in ICU and oxygen supplementation. Multivariate analyses identified age, and pneumonia (46.8%), but not influenza type, to be associated with severe outcomes. Antiviral treatment was given to 37.2% of the patients, while 77.6% received antibiotics. Only 25.5% of patients with influenza B received antiviral therapy.

CONCLUSIONS

The influenza patients were mostly elderly, and few patients were treated in ICU. A high CRB score was associated with severe outcomes with possible implications for patient monitoring. Less than 40% of the patients received antiviral therapy, whereas the majority were treated with antibiotics, indicating potential for optimising treatment strategies.

Combined use of a broad-panel respiratory multiplex PCR and procalcitonin to reduce duration of antibiotics exposure in patients with severe community-acquired pneumonia (MULTI-CAP): a multicentre, parallel-group, open-label, individual randomised trial conducted in French intensive care units

INTRODUCTION

At the time of the worrying emergence and spread of bacterial resistance, reducing the selection pressure by reducing the exposure to antibiotics in patients with community-acquired pneumonia (CAP) is a public health issue. In this context, the combined use of molecular tests and biomarkers for guiding antibiotics discontinuation is attractive. Therefore, we have designed a trial comparing an integrated approach of diagnosis and treatment of severe CAP to usual care.

METHODS AND ANALYSIS

The multiplex PCR and procalcitonin to reduce duration of antibiotics exposure in patients with severe-CAP (MULTI-CAP) trial is a multicentre (n=20), parallel-group, superiority, open-label, randomised trial. Patients are included if adult admitted to intensive care unit for a CAP. Diagnosis of pneumonia is based on clinical criteria and a newly appeared parenchymal infiltrate. Immunocompromised patients are excluded. Subjects are randomised (1:1 ratio) to either the intervention arm (experimental strategy) or the control arm (usual strategy). In the intervention arm, the microbiological diagnosis combines a respiratory multiplex PCR (mPCR) and conventional microbiological investigations. An algorithm of early antibiotic de-escalation or discontinuation is recommended, based on mPCR results and the procalcitonin value. In the control arm, only conventional microbiological investigations are performed and antibiotics de-escalation remains at the clinician's discretion. The primary endpoint is the number of days alive without any antibiotic from the randomisation to day 28. Based on our hypothesis of 2 days gain in the intervention arm, we aim to enrol a total of 450 patients over a 30-month period.

ETHICS AND DISSEMINATION

The MULTI-CAP trial is conducted according to the principles of the Declaration of Helsinki, is registered in Clinical Trials and has been approved by the Committee for Protection of Persons and the National French Drug Safety Agency. Written informed consents are obtained from all the patients (or representatives). The results will be disseminated through educational institutions, submitted to peer-reviewed journals for publication and presented at medical congresses.

TRIAL REGISTRATION NUMBER

NCT03452826; Pre-results.

Novel point-of-care biomarker combination tests to differentiate acute bacterial from viral respiratory tract infections to guide antibiotic prescribing: a systematic review

BACKGROUND

Acute respiratory tract infections (RTIs) are the most common reason to seek medical care, with many patients receiving inappropriate antibiotics. Novel testing approaches to identify aetiology at the point-of-care are required to accurately guide antibiotic treatment.

OBJECTIVE

To assess the diagnostic accuracy of biomarker combinations to rapidly differentiate between acute bacterial or viral RTI aetiology.

DATA SOURCES

MEDLINE, Embase and Web of Science databases were searched to February 2021.

STUDY ELIGIBILITY CRITERIA

Diagnostic accuracy studies comparing accuracy of point-of-care and rapid diagnostic tests in primary or secondary care, consisting of biomarker combinations, to identify bacterial or viral aetiology of RTI.

METHODS

Risk of bias was assessed using the QUADAS-2 tool. Sensitivity and specificity of tests reported by more than one study were meta-analysed using a random effects model.

RESULTS

Twenty observational studies (3514 patients) were identified. Eighteen were judged at high risk of bias. For bacterial aetiologies, sensitivity ranged from 61% to 100% and specificity from 18% to 96%. For viral aetiologies, sensitivity ranged from 59% to 97% and specificity from 74% to 100%. Studies evaluating two commercial tests were meta-analysed. For ImmunoXpert, the summary sensitivity and specificity were 85% (95% CI 75%-91%, k = 4) and 86% (95% CI 73%-93%, k = 4) for bacterial infections, and 90% (95% CI 79%-96%, k = 3) and 92% (95% CI 83%-96%, k = 3) for viral infections, respectively. FebriDx had pooled sensitivity and specificity of 84% (95% CI 75%-90%, k = 4) and 93% (95% CI 90%-95%, k = 4) for bacterial infections, and 87% (95% CI 72%-95%; k = 4) and 82% (95% CI 66%-86%, k = 4) for viral infections, respectively.

CONCLUSION

Combinations of biomarkers show potential clinical utility in discriminating the aetiology of RTIs. However, the limitations in the evidence base, due to a high proportion of studies with high risk of bias, preclude firm conclusions. Future research should be in primary care and evaluate patient outcomes and cost-effectiveness with experimental study designs.

CLINICAL TRIAL

PROSPERO registration number: CRD42020178973.

COVID-19 is not "just another flu": a real-life comparison of severe COVID-19 and influenza in hospitalized patients in Vienna, Austria

Background

COVID-19 is regularly compared to influenza. Mortality and case-fatality rates vary widely depending on incidence of COVID-19 and the testing policy in affected countries. To date, data comparing hospitalized patients with COVID-19 and influenza is scarce.

Methods

Data from patients with COVID-19 were compared to patients infected with influenza A (InfA) and B (InfB) virus during the 2017/18 and 2018/19 seasons. All patients were ≥ 18 years old, had PCR-confirmed infection and needed hospital treatment. Demographic data, medical history, length-of-stay (LOS), complications including in-hospital mortality were analyzed.

Results

In total, 142 patients with COVID-19 were compared to 266 patients with InfA and 300 with InfB. Differences in median age (COVID-19 70.5 years vs InfA 70 years and InfB 77 years, p < 0.001) and laboratory results were observed. COVID-19 patients had fewer comorbidities, but complications (respiratory insufficiency, pneumonia, acute kidney injury, acute heart failure and death) occurred more frequently.

Median length-of-stay (LOS) was longer in COVID-19 patients (12 days vs InfA 7 days vs. InfB 7 days, p < 0.001). There was a fourfold higher in-hospital mortality in COVID-19 patients (23.2%) when compared with InfA (5.6%) or InfB (4.7%; p < 0.001).

Conclusion

In hospitalized patients, COVID-19 is associated with longer LOS, a higher number of complications and higher in-hospital mortality compared to influenza, even in a population with fewer co-morbidities. This data, a high reproduction number and limited treatment options, alongside excess mortality during the SARS-CoV-2 pandemic, support the containment strategies implemented by most authorities.

Comparison of clinical features on admission between coronavirus disease 2019 and influenza a among children: a retrospective study in China

BACKGROUND

Coronavirus disease 2019 (COVID-19) share similar symptoms with influenza A (IA), but it is more worthwhile to understand the disparities of the two infections regarding their clinical characteristics on admission.

METHODS

A total of 71 age-matched pediatric IA and COVID-19 patient pairs were formed and their clinical data on admission were compared.

RESULTS

Fever, cough, nasal congestion and nausea/vomiting were the most common symptoms on admission for both infections but occurred less often in COVID-19. The IA patients were more likely to have lower-than-normal levels of lymphocyte count and percentage and to have higher-than-normal levels of activated partial thromboplastin time, prothrombin time, serum C-reactive protein, and serum procalcitonin, while the COVID-19 patients had higher odds of having lower-than-normal levels of neutrophil count and percentage.

CONCLUSIONS

This study suggests that influenza A is more symptomatic than COVID-19 for children and might be an overall more severe infection at the time of admission.

COVID-19 severe pneumonia: Prospective multicentre study on demands on intensive care capacities

OBJECTIVES

The aim of the study was to obtain data on demands on the intensive care capacities to treat COVID-19 patients, and to identify predictors for in-hospital mortality.

METHODS

The prospective observational multicentre study carried out from 1 March till 30 June 2020 included adult patients with confirmed SARS-CoV-2 infection with respiratory failure requiring ventilatory support or high-flow nasal oxygen therapy (HFNO).

RESULTS

Seventy-four patients, 46 males and 28 females, median age 67.5 (Q1-Q3: 56-75) years, were included. Sixty-four patients (86.5%) had comorbidity. Sixty-six patients (89.2%) were mechanically ventilated, four of them received extracorporeal membrane oxygenation therapy. Eight patients (10.8%) were treated with non-invasive ventilation and HFNO only. The median of intensive care unit (ICU) stay was 22.5 days. Eighteen patients (24.3%) needed continuous renal replacement therapy. Thirty patients (40.5%) died. Age and acute kidney injury were identified as independent predictors of in-hospital death, and chronic kidney disease showed trend towards statistical significance for poor outcome.

CONCLUSIONS

Sufficient number of intensive care beds, organ support equipment and well-trained staff is a decisive factor in managing the COVID-19 epidemic. The study focused on the needs of intensive care in the COVID-19 patients. Advanced age and acute kidney injury were identified as independent predictors for in-hospital mortality. When compared to clinical course and ICU management of patients with severe community-acquired pneumonia caused by other pathogens, we observed prolonged need for ventilatory support, high rate of progression to acute respiratory distress syndrome and significant mortality in studied population.

Sudden death of COVID-19 patients in Wuhan, China: A retrospective cohort study

Background

In December 2019, coronavirus disease 2019 (COVID-19) emerged in Wuhan city and rapidly spread throughout China. So far, it has caused ~ 4000 deaths in this country. We aimed to systematically characterize clinical features and determine risk factors of sudden death for COVID-19 patients.

Methods

Deceased patients with COVID-19 in Tongji hospital from January 22 to March 23, 2020 were extracted. Patients who died within 24 hours after admission were identified as sudden deaths, and the others formed non-sudden deaths. The differences in clinical characteristics between the two groups were estimated. Risk factors associated with sudden deaths were explored by logistic regression.

Results

281 deceased patients were enrolled in this study. Sudden death occurred in 28 (10.0%) patients, including 4 (14.3%) admitted to the intensive care unit. Fatigue was more common in sudden deaths (11, 47.8%) than in non-sudden deaths (40, 17.2%). Both the count and percentage of eosinophils were lower in sudden deaths than that in non-sudden deaths (P = 0.006 and P = 0.004). Compared with non-sudden deaths, sudden deaths had higher plasma levels of procalcitonin, C-reactive protein, D-dimer, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, lactate dehydrogenase, alkaline phosphatase and N-terminal pro-brain natriuretic peptide. There were not significant differences in gender, age, chest CT image features and comorbidities observed.

Conclusions

The differences between the two groups suggested more severe systemic inflammation, multi-organ dysfunction, especially impaired liver and heart function in COVID-19 patients who died suddenly after admission. More researches are needed to verify these points.

Use of procalcitonin and C-reactive protein in the diagnosis of bacterial infection in infants with severe bronchiolitis

The objective was to evaluate the use of procalcitonin (PCT) and C-reactive protein (CRP) for the diagnosis of bacterial infection in bronchiolitis patients. A prospective, single-centre, descriptive, and comparative observational study was carried out on patients with severe bronchiolitis admitted to the paediatric intensive care unit (PICU), from January 2011 to July 2017. Two cohorts were compared: patients with invasive bacterial infection (IBI) and patients with no bacterial infection (NBI). We included 675 patients, 399 of whom were males (59.1%), with median age of 47 days (IQR 25-100.3). Of them, 181 patients were diagnosed with IBI (26.8%). Seventy-two had sepsis (10.7%), 106 had pneumonia (15.7%), and 41 had a urinary tract infection (6.1%). PCT and CRP values were significantly higher in patients with IBI. ROC curves compared the ability of PCT and CRP to diagnose IBI at admission, 24 h, and 48 h. PCT showed a better AUC for diagnosing IBI, with statistically significant differences at all time points (p < 0.001). The best PCT cut-off for IBI diagnosis at admission was 1.4 ng/mL, with a sensitivity of 69% (95% CI 58.4-74.9) and a specificity of 91% (95% CI 88.1-92.5). Procalcitonin showed a better AUC for diagnosing both sepsis and pneumonia, which makes it an excellent predictor.Conclusion: We present PCT as a novel test in comparison with the traditional CRP screening test to discern which bronchiolitis patients have IBI. We highlight the importance of PCT for the diagnosis of pneumonia and sepsis, as it proved to be more sensitive and specific than CRP, with statistically significant differences. What is Known: • Bronchiolitis should be treated with antibiotics only when a bacterial infection is present. • The rate of antibiotic prescription in severe bronchiolitis is extremely high, so diagnostic tools are needed. What is New: • PCT is a good biomarker to discern which bronchiolitis patients have IBI, specially for pneumonia and sepsis diagnoses. It is more sensitive and specific than CRP, with statistically significant differences. • Implementation of PCT cut-off values may prevent unnecessary antibiotic use.

Identification of key candidate biomarkers for severe influenza infection by integrated bioinformatical analysis and initial clinical validation

One of the key barriers for early identification and intervention of severe influenza cases is a lack of reliable immunologic indicators. In this study, we utilized differentially expressed genes screening incorporating weighted gene co‐expression network analysis in one eligible influenza GEO data set (GSE111368) to identify hub genes associated with clinical severity. A total of 10 genes (PBI, MMP8, TCN1, RETN, OLFM4, ELANE, LTF, LCN2, DEFA4 and HP) were identified. Gene set enrichment analysis (GSEA) for single hub gene revealed that these genes had a close association with antimicrobial response and neutrophils activity. To further evaluate these genes' ability for diagnosis/prognosis of disease developments, we adopted double validation with (a) another new independent data set (GSE101702); and (b) plasma samples collected from hospitalized influenza patients. We found that 10 hub genes presented highly correlation with disease severity. In particular, BPI and MMP8 encoding proteins in plasma achieved higher expression in severe and dead cases, which indicated an adverse disease development and suggested a frustrating prognosis. These findings provide new insight into severe influenza pathogenesis and identify two significant candidate genes that were superior to the conventional clinical indicators. These candidate genes or encoding proteins could be biomarker for clinical diagnosis and therapeutic targets for severe influenza infection.

Procalcitonin to Distinguish Viral From Bacterial Pneumonia: A Systematic Review and Meta-analysis

Because of the diverse etiologies of community-acquired pneumonia (CAP) and the limitations of current diagnostic modalities, serum procalcitonin levels have been proposed as a novel tool to guide antibiotic therapy. Outcome data from procalcitonin-guided therapy trials have shown similar mortality, but the essential question is whether the sensitivity and specificity of procalcitonin levels enable the practitioner to distinguish bacterial pneumonia, which requires antibiotic therapy, from viral pneumonia, which does not. In this meta-analysis of 12 studies in 2408 patients with CAP that included etiologic diagnoses and sufficient data to enable analysis, the sensitivity and specificity of serum procalcitonin were 0.55 (95% confidence interval [CI], .37-.71; I2 = 95.5%) and 0.76 (95% CI, .62-.86; I2 = 94.1%), respectively. Thus, a procalcitonin level is unlikely to provide reliable evidence either to mandate administration of antibiotics or to enable withholding such treatment in patients with CAP.

A Risk Prediction Model for Evaluating the Disease Progression of COVID-19 Pneumonia

Background and Objective: The epidemic of coronavirus disease 2019 (COVID-19) pneumonia caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) has expanded from China throughout the world. This study aims to estimate the risk of disease progression of patients who have been confirmed with COVID-19. Methods: Meta-analysis was performed in existing literatures to identify risk factors associated with COVID-19 pneumonia progression. Patients with COVID-19 pneumonia were admitted to hospitals in Wuhan or Hangzhou were retrospectively enrolled. The risk prediction model and nomogram were developed from Wuhan cohort through logistic regression algorithm, and then validated in Hangzhou and Yinchuan cohorts. Results: A total of 270 patients admitted to hospital between Dec 30, 2019, and Mar 30, 2020, were retrospectively enrolled (Table 1). The development cohort (Wuhan cohort) included 87 (43%) men and 115 (57%) women, and the median age was 53 years old. Hangzhou validation cohort included 20 (48%) men and 22 (52%) women, and the median age was 59 years old. Yinchuan validation cohort included 12 (46%) men and 14 (54%) women, and the median age was 44 years old. The meta-analysis along with univariate logistic analysis in development cohort have shown that age, fever, diabetes, hypertension, CREA, BUN, CK, LDH, and neutrophil count were significantly associated with disease progression of COVID-19 pneumonia. The model and nomogram derived from development cohort show good performance in both development and validation cohorts. Conclusion: The severe COVID-19 pneumonia is associated with various types of risk factors including age, fever, comorbidities, and some laboratory examination indexes. The model integrated with these factors can help to evaluate the disease progression of COVID-19 pneumonia.

Procalcitonin Identifies Bacterial Coinfections in Vietnamese Children with Severe Respiratory Syncytial Virus Pneumonia

This study assessed the diagnostic value of interleukin- (IL-) 6, high-sensitivity C-reactive protein (hs-CRP), and procalcitonin (PCT) in differentiating severe pneumonia caused by respiratory syncytial virus (RSV) alone and RSV with bacterial coinfections among Vietnamese children under 5 years old. A cross-sectional study on 70 children with severe RSV pneumonia was conducted. IL-6, hs-CRP, and PCT tests were performed. Receiver operating characteristic (ROC) analysis was employed to measure the diagnostic values of PCT, IL-6, and hs-CRP. Of 70 children, 11 children were confirmed to have bacterial coinfections. The most common bacterial coinfection was Haemophilus influenzae. This study underlined that inflammatory biomarkers such as PCT had a moderate-to-high capability of disseminating severe pneumonia children with RSV alone or RSV and bacterial coinfections. This may support clinicians in administrating appropriate antibiotics to children suffering from severe RSV pneumonia.

How can biomarkers be used to differentiate between infection and non-infectious causes of inflammation?

Diagnosis of sepsis is based on recognition of systemic inflammation and organ failure in the context of an inciting infection. Since none of the diagnostic criteria are specific to sepsis, it is easy to confound sepsis with noninfectious causes of systemic inflammation, including pancreatitis, cardiac ischemia, bowel perforation, vasculitis, and pulmonary embolism amongst others. Two widely used biomarkers, C-reactive protein and procalcitonin, have proven promising in sepsis diagnosis. Each has found varying success in the clinical context, with some centers relying heavily on these markers and others eschewing their use almost entirely. In this chapter, we present the evidence for their use in the diagnosis of sepsis and management of antibiotic therapy in the intensive care unit context.

Biomarkers of Community-Acquired Pneumonia: A Key to Disease Diagnosis and Management

Community-acquired pneumonia (CAP) is a dangerous disease caused by a spectrum of bacterial and viral pathogens. The choice of specific therapy and the need for hospitalization or transfer to the intensive care unit are determined by the causative agent and disease severity. The microbiological analysis of sputum largely depends on the quality of the material obtained. The prediction of severity and the duration of therapy are determined individually, and existing prognostic scales are used generally. This review examines the possibilities of using specific serological biomarkers to detect the bacterial or viral aetiology of CAP and to assess disease severity. Particular emphasis is placed on the use of biomarker signatures and the discovery of biomarker candidates for a single multiplex analysis.

Combination of procalcitonin and C-reactive protein levels in the early diagnosis of bacterial co-infections in children with H1N1 influenza

Objective

This study evaluated the diagnostic value of measuring the levels of procalcitonin (PCT) and C‐reactive protein (CRP) to differentiate children co‐infected with H1N1 influenza and bacteria from children infected with H1N1 influenza alone.

Methods

Consecutive patients (children aged < 5 years) with laboratory‐confirmed H1N1 influenza who were hospitalized or received outpatient care from a tertiary‐care hospital in Canton, China, between January 1, 2012, and September 1, 2017, were included in the present study. Laboratory results, including serum PCT and CRP levels, white blood cell (WBC) counts, and bacterial cultures, were analyzed. The predictive value of the combination of biomarkers versus any of the biomarkers alone for diagnosing bacterial co‐infections was evaluated using logistic regression analyses.

Results

Significantly higher PCT (1.46 vs 0.21 ng/mL, P < 0.001) and CRP (19.20 vs 5.10 mg/dL, P < 0.001) levels were detected in the bacterial co‐infection group than in the H1N1 infection‐alone group. Using PCT or CRP levels alone, the areas under the curves (AUCs) for predicting bacterial co‐infections were 0.801 (95% CI, 0.772‐0.855) and 0.762 (95% CI, 0.722‐0.803), respectively. Using a combination of PCT and CRP, the logistic regression‐based model, Logit(P) = −1.912 + 0.546 PCT + 0.087 CRP, showed significantly greater accuracy (AUC: 0.893, 95% CI: 0.842‐0.934) than did the other three biomarkers.

Conclusions

The combination of PCT and CRP levels could provide a useful method of distinguishing bacterial co‐infections from an H1N1 influenza infection alone in children during the early disease phase. After further validation, the flexible model derived here could assist clinicians in decision‐making processes.

Procalcitonin for clinical decisions on influenza-like illness in emergency department during influenza a(H1N1)2009 pandemic

PURPOSE

We aimed to determine whether serum procalcitonin (PCT) values could help in identifying flu in patient admitted to the emergency department (ED) with influenza-like illness (ILI) during influenza A(H1N1)2009 pandemic.

METHODS

An observational retrospective cohort study was performed in a referral ED for emerging infectious diseases. All patients tested for influenza A(H1N1)2009 by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) and procalcitonin between June 2009 and January 2010 were analyzed. PCT was studied for its negative predictive value of bacterial infection. Patients PCT-/RT-PCR + were considered as true positive.

RESULTS

On the 80 patients included, 16 were positive for influenza A(H1N1)2009 RT-PCR, all but one of them had low PCT concentrations. Conversely, 19 (30%) of the 64 patients with negative RT-PCR had elevated PCT concentrations. For a PCT threshold <0.25 μg/L, sensitivity was 0.94, specificity 0.30, positive predictive value 0.25 and negative predictive value 0.95 for the diagnosis of flu.

CONCLUSION

In the context of an influenza pandemic, serum PCT measurement may be useful for clinical decisions in the ED as most of RT-PCR confirmed patients have low PCT values. Patients with PCT above 0.25 μg/L are unlikely to have a unique diagnosis of flu.

Serum Procalcitonin and Peripheral Venous Lactate for Predicting Dengue Shock and/or Organ Failure: A Prospective Observational Study

Background

Currently, there are no biomarkers that can predict the incidence of dengue shock and/or organ failure, although the early identification of risk factors is important in determining appropriate management to reduce mortality. Therefore, we sought to determine the factors associated with dengue shock and/or organ failure and to evaluate the prognostic value of serum procalcitonin (PCT) and peripheral venous lactate (PVL) levels as biomarkers of dengue shock and/or organ failure.

Methodology/Principal Findings

A prospective observational study was conducted among adults hospitalized for confirmed viral dengue infection at the Hospital for Tropical Diseases in Bangkok, Thailand between October 2013 and July 2015. Data, including baseline characteristics, clinical parameters, laboratory findings, serum PCT and PVL levels, management, and outcomes, were recorded on pre-defined case report forms. Of 160 patients with dengue, 128 (80.0%) patients had dengue without shock or organ failure, whereas 32 (20.0%) patients developed dengue with shock and/or organ failure. Using a stepwise multivariate logistic regression analysis, PCT ≥0.7 ng/mL (odds ratio [OR]: 4.80; 95% confidence interval [CI]: 1.60–14.45; p = 0.005) and PVL ≥2.5 mmol/L (OR: 27.99, 95% CI: 8.47–92.53; p <0.001) were independently associated with dengue shock and/or organ failure. A combination of PCT ≥0.7 ng/mL and PVL ≥2.5 mmol/L provided good prognostic value for predicting dengue shock and/or organ failure, with an area under the receiver operating characteristics curve of 0.83 (95% CI: 0.74–0.92), a sensitivity of 81.2% (95% CI: 63.6–92.8%), and a specificity of 84.4% (95% CI: 76.9–90.2%). Dengue shock patients with non-clearance of PCT and PVL expired during hospitalization.

Conclusions/Significance

PCT ≥0.7 ng/mL and PVL ≥2.5 mmol/L were independently associated with dengue shock and/or organ failure. The combination of PCT and PVL levels could be used as prognostic biomarkers for the prediction of dengue shock and/or organ failure.

Dengue is a major global health concern, particularly in tropical countries, and affects all age groups. Mortality rates among patients who have been hospitalized with severe dengue are 1.6–10.9%, and death in adults is mainly due to the development of dengue shock and organ dysfunction. In states of poor tissue circulation or shock, lactate is produced. Additionally, procalcitonin is a highly specific biomarker of systemic inflammation. Therefore, we assessed whether procalcitonin and peripheral venous lactate could be used to predict the incidence of dengue shock and/or organ failure in patients with dengue. Our study showed that a combination of serum procalcitonin levels ≥0.7 ng/mL and peripheral venous lactate levels ≥2.5 mmol/L at admission could discriminate between patients who did and did not develop shock and/or organ failure, with high sensitivity and specificity. These parameters may therefore be useful as prognostic biomarkers. Our results suggest that serum procalcitonin is indicative of an extensive early inflammatory response, which may occur during the systemic phase of dengue. Peripheral venous lactate may be produced as a result of the poor tissue circulation that precedes dengue shock. Our findings may help clinicians to predict dengue shock and/or organ failure earlier to reduce in-hospital mortality.

The frequency of influenza and bacterial coinfection: a systematic review and meta-analysis

Aim

Coinfecting bacterial pathogens are a major cause of morbidity and mortality in influenza. However, there remains a paucity of literature on the magnitude of coinfection in influenza patients.

Method

A systematic search of MeSH, Cochrane Library, Web of Science, SCOPUS, EMBASE, and PubMed was performed. Studies of humans in which all individuals had laboratory confirmed influenza, and all individuals were tested for an array of common bacterial species, met inclusion criteria.

Results

Twenty‐seven studies including 3215 participants met all inclusion criteria. Common etiologies were defined from a subset of eight articles. There was high heterogeneity in the results (I² = 95%), with reported coinfection rates ranging from 2% to 65%. Although only a subset of papers were responsible for observed heterogeneity, subanalyses and meta‐regression analysis found no study characteristic that was significantly associated with coinfection. The most common coinfecting species were Streptococcus pneumoniae and Staphylococcus aureus, which accounted for 35% (95% CI, 14%–56%) and 28% (95% CI, 16%–40%) of infections, respectively; a wide range of other pathogens caused the remaining infections. An assessment of bias suggested that lack of small‐study publications may have biased the results.

Conclusions

The frequency of coinfection in the published studies included in this review suggests that although providers should consider possible bacterial coinfection in all patients hospitalized with influenza, they should not assume all patients are coinfected and be sure to properly treat underlying viral processes. Further, high heterogeneity suggests additional large‐scale studies are needed to better understand the etiology of influenza bacterial coinfection.

Biomarker kinetics in the prediction of VAP diagnosis: results from the BioVAP study

Background

Prediction of diagnosis of ventilator-associated pneumonia (VAP) remains difficult. Our aim was to assess the value of biomarker kinetics in VAP prediction.

Methods

We performed a prospective, multicenter, observational study to evaluate predictive accuracy of biomarker kinetics, namely C-reactive protein (CRP), procalcitonin (PCT), mid-region fragment of pro-adrenomedullin (MR-proADM), for VAP management in 211 patients receiving mechanical ventilation for >72 h. For the present analysis, we assessed all (N = 138) mechanically ventilated patients without an infection at admission. The kinetics of each variable, from day 1 to day 6 of mechanical ventilation, was assessed with each variable’s slopes (rate of biomarker change per day), highest level and maximum amplitude of variation (Δ^max).

Results

A total of 35 patients (25.4 %) developed a VAP and were compared with 70 non-infected controls (50.7 %). We excluded 33 patients (23.9 %) who developed a non-VAP nosocomial infection. Among the studied biomarkers, CRP and CRP ratio showed the best performance in VAP prediction. The slope of CRP change over time (adjusted odds ratio [aOR] 1.624, confidence interval [CI]_95% [1.206, 2.189], p = 0.001), the highest CRP ratio concentration (aOR 1.202, CI_95% [1.061, 1.363], p = 0.004) and Δ^max CRP (aOR 1.139, CI_95% [1.039, 1.248], p = 0.006), during the first 6 days of mechanical ventilation, were all significantly associated with VAP development. Both PCT and MR-proADM showed a poor predictive performance as well as temperature and white cell count.

Conclusions

Our results suggest that in patients under mechanical ventilation, daily CRP monitoring was useful in VAP prediction.

Trial registration NCT02078999

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-016-0134-8) contains supplementary material, which is available to authorized users.

Personalized medicine in severe influenza

Existing therapies against infectious diseases may only be effective in limited subpopulations during specific phases of diseases, incorporating theranostics, and there is a clear need to individualize different therapeutic approaches depending on the host. Influenza A virus infection evolves into a severe respiratory failure in some young adult patients, related to an exaggerated inflammatory response. Mortality rates remain high despite antiviral treatment and aggressive respiratory support. The influenza A virus (IAV) infection will induce a proinflammatory innate immune response through recognition of viral RNA by Toll-like receptor (TLR) 7 and retinoic acid-inducible gene 1 (RIG-I) molecules by nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB route). Anti-inflammatory therapies focused on modulating this inflammatory response to “all patients” have not been satisfactory. Steroids should be avoided because they do not improve survival and promote superinfections. Since clinical judgment has often been proven inadequate, interest in the use of biomarkers to monitor host response and to assess severity and complications is growing. It is well known that, if used appropriately, these can be helpful tools to predict not only severity but also mortality. We need more biomarkers that predict host response: it is time to change lactate measurement to proteomics and transcriptomics. Theranostics describes an approach covering both diagnosis and coupled therapy. Death is usually a fatal complication of a dysregulated immune response more than the acute virulence of the infectious agent. Future research demonstrating the usefulness of adjunctive therapy in a subset of critically ill patients with IAV pneumonia is an unmet clinical need.

The association of serum procalcitonin and high-sensitivity C-reactive protein with pneumonia in elderly multimorbid patients with respiratory symptoms: retrospective cohort study

BACKGROUND

Serum procalcitonin and high-sensitivity C-reactive protein (hs-CRP) elevations have been associated with pneumonia in adults. Our aim was to establish their diagnostic usefulness in a cohort of hospitalized multimorbid patients ≥65 years old admitted to hospital with acute respiratory symptoms.

METHODS

With a retrospective cohort study design, all multimorbid patients ≥65 years-old with acute respiratory symptoms admitted to an internal medicine hospital ward in Italy from January to August 2013 were evaluated. Pneumonia diagnosis, comorbidities expressed through Cumulative Illness Rating Scale (CIRS), setting of living, length of stay, serum hs-CRP and procalcitonin at admission were collected for each patient. Data were analyzed with Mann-Whitney's U test and multivariate Cox logistic regression analysis. A Receiver Operating Characteristic (ROC) curve was used to verify each biomarker's association with pneumonia diagnosis.

RESULTS

Four hundred fifty five patients (227 M) were included in the study, of whom 239 with pneumonia (138 M, mean age 80 ± 13) and 216 without pneumonia (89 M, mean age 80 ± 14). After adjustment for age and sex, median levels of hs-CRP were significantly higher in patients with pneumonia (116 mg/L, IQR 46.5-179.0, vs 22.5 mg/dl, IQR 6.9-84.4, p < 0.0001), while procalcitonin median levels were not (0.22 ng/ml IQR 0.12-0.87, vs 0.15 ng/ml, IQR 0.10-0.35, p = 0.08). The ROC analysis showed that, unlike procalcitonin, hs-CRP values were predictive of pneumonia (AUC 0.76, 95% CI 0.72-0.79, p < 0.0001, cut-off value 61 mg/L), even after adjustment for possible confounders including nursing home residence and dementia. Serum hs-CRP levels >61 mg/L were independently associated with a 3.59-fold increased risk of pneumonia (OR 3.59, 95% CI 2.35-5.48, p < 0.0001).

CONCLUSION

In elderly multimorbid patients who require hospital admission for respiratory symptoms, serum hs-CRP testing seems to be more useful than procalcitonin for guiding the diagnostic process when clinical suspicion of pneumonia is present. Procalcitonin testing might hence be not recommended in this setting.

Bacterial coinfection is associated with severity of avian influenza A (H7N9), and procalcitonin is a useful marker for early diagnosis

Patients contracting avian influenza A (H7N9) often develop severe disease. However, information on the contribution of bacterial coinfection to the severity of H7N9 is limited. We retrospectively studied 83 patients with confirmed H7N9 infection from April 2013 to February 2014. The severity of patients with bacterial coinfection and markers for early diagnosis of bacterial coinfection in H7N9 were analyzed. We found Staphylococcus aureus was the most prevalent pathogen. Higher Acute Physiology and Chronic Health Evaluation II score, shock, renal replacement treatment, mechanical ventilation, and extracorporeal membrane oxygenation treatment were more frequently observed in patients with bacterial coinfection. Procalcitonin is more sensitive than C-reactive protein in determining bacterial coinfection in H7N9 patients. In conclusion, H7N9 infection patients with bacterial coinfection had a more severe condition. Elevated procalcitonin is an accurate marker for diagnosing bacterial coinfection in H7N9 patients, thus enabling earlier antibiotic therapy.

Polymicrobial community-acquired pneumonia: An emerging entity

Polymicrobial aetiology in community-acquired pneumonia (CAP) is more common than previously recognized. This growing new entity can influence inflammation, host immunity and disease outcomes in CAP patients. However, the true incidence is complicated to determine and probably underestimated due mainly to many cases going undetected, particularly in the outpatient setting, as the diagnostic yield is restricted by the sensitivity of currently available microbiologic tests and the ability to get certain types of clinical specimens. The observed rate of polymicrobial cases may also lead to new antibiotic therapy considerations. In this review, we discuss the pathogenesis, microbial interactions in pneumonia, epidemiology, biomarkers and antibiotic therapy for polymicrobial CAP.

Retrospective study of risk factors for mortality in human avian influenza A(H7N9) cases in Zhejiang Province, China, March 2013 to June 2014

BACKGROUND

The influenza A(H7N9) virus causes a serious disease that threatens human health. Fatalities associated with human infections caused by this virus are of great public health concern; however, the possible risk factors are not yet fully known.

METHODS

A stratified sampling method, incorporating household income levels and a random number table method, was used to select laboratory-confirmed A(H7N9) cases for this study. Eighty-five patients were selected randomly from 139 laboratory-confirmed A(H7N9) cases occurring in Zhejiang Province between March 1, 2013 and June 30, 2014. Data were collected using a standard method. To test the statistical significance among discrete variables, univariate analyses were used to compare two groups. The Kaplan-Meier product-limit method was used to analyze the patient survival fraction. The Cox proportional hazards regression model was used to analyze all variables with p ≤ 0.05 in the univariate analysis. Lastly, a stepwise procedure was used to construct a final model with a significance level of p > 0.10 for removal and p<0.05 for re-entry.

RESULTS

A total of 85 patients with H7N9 virus infection were identified. Among these, 30 (35.29%) died. In the univariate analysis, the following factors were associated with a high risk of influenza A(H7N9) case fatality: age ≥ 60 years (p=0.008), low education level (p=0.030), chronic diseases (p=0.029), poor hand hygiene (p=0.010), time from illness onset to the first medical visit (p=0.029) and to intensive care unit admission (p=0.008), an incubation period of ≤ 5 days (p=0.039), a peak C-reactive protein ≥ 120 mg/l (p=0.012), increased initial neutrophil count (p=0.020), decreased initial lymphocyte count (p=0.021), and initial infection of both lungs (p=0.003). Multivariate analysis confirmed that the independent predictors of H7N9 virus infection mortality in Zhejiang, China were hand hygiene (hazard ratio (HR) 5.163, 95% confidence interval (CI) 1.164-22.661), age (HR 1.042, 95% CI 1.007-1.076), and peak CRP (HR 1.009, 95% CI 1.002-1.016).

CONCLUSIONS

Improvements in immunity, early case identification and treatment, and personal protection measures are key to addressing the high human avian influenza A(H7N9) case fatality rate.

Pros and cons of using biomarkers versus clinical decisions in start and stop decisions for antibiotics in the critical care setting

INTRODUCTION

Patients in the intensive care unit (ICU) frequently receive prolonged or even unnecessary antibiotic therapy, which selects for antibiotic-resistant bacteria. Over the last decade there has been great interest in biomarkers, particularly procalcitonin, to reduce antibiotic exposure.

METHODS

In this narrative review, we discuss the value of biomarkers and provide additional information beyond clinical evaluation in order to be clinically useful and review the literature on sepsis biomarkers outside the neonatal period. Both benefits and limitations of biomarkers for clinical decision-making are reviewed.

RESULTS

Several randomized controlled trials (RCTs) have shown the safety and efficacy of procalcitonin to discontinue antibiotic therapy in patients with severe sepsis or septic shock. In contrast, there is limited utility of procalcitonin for treatment initiation or withholding therapy initially. In addition, an algorithm using procalcitonin for treatment escalation has been ineffective and is probably associated with poorer outcomes. Little data from interventional studies are available for other biomarkers for antibiotic stewardship, except for C-reactive protein (CRP), which was recently found to be similarly effective and safe as procalcitonin in a randomized controlled trial. We finally briefly discuss biomarker-unrelated approaches to reduce antibiotic duration in the ICU, which have shown that even without biomarker guidance, most patients with sepsis can be treated with relatively short antibiotic courses of approximately 7 days.

CONCLUSIONS

In summary, there is an ongoing unmet need for biomarkers which can reliably and early on identify patients who require antibiotic therapy, distinguish between responders and non-responders and help to optimize antibiotic treatment decisions among critically ill patients. Available evidence needs to be better incorporated in clinical decision-making.

Adults hospitalised with acute respiratory illness rarely have detectable bacteria in the absence of COPD or pneumonia; viral infection predominates in a large prospective UK sample

OBJECTIVES

Many adult patients hospitalised with acute respiratory illness have viruses detected but the overall importance of viral infection compared to bacterial infection is unclear.

METHODS

Patients were recruited from two acute hospital sites in Leicester (UK) over 3 successive winters. Samples were taken for viral and bacterial testing.

RESULTS

Of the 780 patients hospitalised with acute respiratory illness 345 (44%) had a respiratory virus detected. Picornaviruses were the most commonly isolated viruses (detected in 23% of all patients). Virus detection rates exceeded 50% in patients with exacerbation of asthma (58%), acute bronchitis and Influenza-like-illness (64%), and ranged from 30 to 50% in patients with an exacerbation of COPD (38%), community acquired pneumonia (36%) and congestive cardiac failure (31%). Bacterial detection was relatively frequent in patients with exacerbation of COPD and pneumonia (25% and 33% respectively) but was uncommon in all other groups. Antibiotic use was high across all clinical groups (76% overall) and only 21% of all antibiotic use occurred in patients with detectable bacteria.

CONCLUSIONS

Respiratory viruses are the predominant detectable aetiological agents in most hospitalised adults with acute respiratory illness. Antibiotic usage in hospital remains excessive including in clinical conditions associated with low rates of bacterial detection. Efforts at reducing excess antibiotic use should focus on these groups as a priority. Registered International Standard Controlled Trial Number: 21521552.

Inflammatory response in mixed viral-bacterial community-acquired pneumonia

Background

The role of mixed pneumonia (virus + bacteria) in community-acquired pneumonia (CAP) has been described in recent years. However, it is not known whether the systemic inflammatory profile is different compared to monomicrobial CAP. We wanted to investigate this profile of mixed viral-bacterial infection and to compare it to monomicrobial bacterial or viral CAP.

Methods

We measured baseline serum procalcitonin (PCT), C reactive protein (CRP), and white blood cell (WBC) count in 171 patients with CAP with definite etiology admitted to a tertiary hospital: 59 (34.5%) bacterial, 66 (39.%) viral and 46 (27%) mixed (viral-bacterial).

Results

Serum PCT levels were higher in mixed and bacterial CAP compared to viral CAP. CRP levels were higher in mixed CAP compared to the other groups. CRP was independently associated with mixed CAP. CRP levels below 26 mg/dL were indicative of an etiology other than mixed in 83% of cases, but the positive predictive value was 45%. PCT levels over 2.10 ng/mL had a positive predictive value for bacterial-involved CAP versus viral CAP of 78%, but the negative predictive value was 48%.

Conclusions

Mixed CAP has a different inflammatory pattern compared to bacterial or viral CAP. High CRP levels may be useful for clinicians to suspect mixed CAP.

The role of immune and metabolic biomarkers for improved management of sepsis patients

Sepsis, the body`s overwhelming response to systemic infections, is responsible for significant morbidity, mortality, and financial burden. Pathogens and their antigens stimulate pro- and anti-inflammatory mediators and immune markers which characterize the host defense and orchestrate leukocyte recruitment to the acute site of infection. Different immune and metabolic biomarkers have been studied in relation to sepsis for their diagnostic and/or prognostic aid. Recent studies have provided abundant evidence that specific immune and metabolic biomarkers improve a physician`s ability to guide early sepsis recognition, severity assessment and therapeutic decisions in individual patients. This may allow for a transition from bundled sepsis care (protocols combining several medical practices) to more individualized management. First, lactate has now been widely used for risk stratification and guidance of fluid resuscitation. Second, procalcitonin correlates with risks of bacterial infections and helps guide therapeutic decisions about initiation and withdrawal of anti-microbial therapy. Third, prognostic markers such as pro-adrenomedullin improve early mortality prediction and thereby site-of-care decisions in respiratory infections. For these markers interventional trials have documented their value when integrated in clinical protocols.

Procalcitonin for diagnosis of bacterial pneumonia in critically ill patients during 2009 H1N1 influenza pandemic: a prospective cohort study, systematic review and individual patient data meta-analysis

Introduction

Procalcitonin (PCT) is helpful for diagnosing bacterial infections. The diagnostic utility of PCT has not been examined thoroughly in critically ill patients with suspected H1N1 influenza.

Methods

Clinical characteristics and PCT were prospectively assessed in 46 patients with pneumonia admitted to medical ICUs during the 2009 and 2010 influenza seasons. An individual patient data meta-analysis was performed by combining our data with data from five other studies on the diagnostic utility of PCT in ICU patients with suspected 2009 pandemic influenza A(H1N1) virus infection identified by performing a systematic literature search.

Results

PCT levels, measured within 24 hours of ICU admission, were significantly elevated in patients with bacterial pneumonia (isolated or coinfection with H1N1; n = 77) (median = 6.2 μg/L, interquartile range (IQR) = 0.9 to 20) than in patients with isolated H1N1 influenza pneumonia (n = 84; median = 0.56 μg/L, IQR = 0.18 to 3.33). The area under the curve of the receiver operating characteristic curve of PCT was 0.72 (95% confidence interval (CI) = 0.64 to 0.80; P < 0.0001) for diagnosis of bacterial pneumonia, but increased to 0.76 (95% CI = 0.68 to 0.85; P < 0.0001) when patients with hospital-acquired pneumonia and immune-compromising disorders were excluded. PCT at a cut-off of 0.5 μg/L had a sensitivity (95% CI) and a negative predictive value of 80.5% (69.9 to 88.7) and 73.2% (59.7 to 84.2) for diagnosis of bacterial pneumonia, respectively, which increased to 85.5% (73.3 to 93.5) and 82.2% (68.0 to 92.0) in patients without hospital acquired pneumonia or immune-compromising disorder.

Conclusions

In critically ill patients with pneumonia during the influenza season, PCT is a reasonably accurate marker for detection of bacterial pneumonia, particularly in patients with community-acquired disease and without immune-compromising disorders, but it might not be sufficient as a stand-alone marker for withholding antibiotic treatment.

Clinical courses and outcomes of hospitalized adult patients with seasonal influenza in Korea, 2011-2012: Hospital-based Influenza Morbidity & Mortality (HIMM) surveillance

Influenza is an acute respiratory illness, which can be accompanied by complications such as pneumonia. This study was conducted to survey the clinical courses and outcomes of hospitalized adult patients with laboratory-confirmed seasonal influenza. A prospective case-control study was performed in adult influenza patients who were admitted to hospitals participating in the Hospital-based Influenza Morbidity and Mortality (HIMM) surveillance system in Korea from October 2011 to May 2012. Cases with complicated influenza were compared to those without complications. A total of 123 (5.6%) patients among 2184 laboratory-confirmed adult influenza patients were hospitalized during the 2011-2012 influenza epidemic season. Forty (32.5%) experienced 50 complication episodes. Age older than 60 years (P < 0.01), male sex (P = 0.04), diabetes (P < 0.01), chronic cardiovascular disease (P < 0.01) and neuromuscular disease (P = 0.02) were significantly related to development of complications in univariate analysis. Multivariate logistic regression analysis revealed that diabetes (odds ratio [OR] 3.63, 95% confidence interval [CI] 1.15-11.51, P = 0.02) was an independent risk factor for complicated seasonal influenza. C-reactive protein (CRP) was discriminative between complicated and uncomplicated influenza (cutoff value 13 mg/L, sensitivity 70%, specificity 74%). Complicated patients received antibiotics more frequently (P < 0.01) with longer hospital stays (P = 0.01). In conclusion, diabetic patients are at great risk for complicated influenza, and CRP would be useful to predicting complication. Therefore, early interventions such as antiviral therapy should be considered for high risk patients with diabetes, especially those with increased serum CRP level.

Rianimazione e influenza grave: pandemia influenzale A (H1N1)

Durante la pandemia influenzale A (H1N1) nel 2009-2010, il 20% dei pazienti ospedalizzati ha presentato delle forme gravi con trasferimento in rianimazione. L’età mediana di questi pazienti era di circa 30 anni, con una percentuale leggermente inferiore al 10% di donne gravide. Si riscontrava circa un 80% di comorbilità, essenzialmente malattie cardiorespiratorie e obesità. Il tempo mediano tra la comparsa della sindrome influenzale e il trasferimento in rianimazione era di un giorno. I test di diagnosi rapida sono realizzabili a partire da semplici campioni respiratori, ma la loro sensibilità rimane bassa. La durata mediana del ricovero in rianimazione era dell’ordine di 11 giorni. Circa il 70% dei pazienti ha richiesto una ventilazione meccanica (durata mediana di dieci giorni). Oltre il 95% di questi pazienti ha ricevuto un trattamento antivirale e oltre il 95% degli antibiotici, a fronte di un 20% soltanto di infezioni batteriche documentate, soprattutto da Streptococcus pneumoniae e Staphylococcus aureus. La mortalità globale a 28 giorni era del 17%. Il tempo mediano tra la comparsa della sindrome influenzale e il decesso era di 14 giorni. Fra questi decessi, la maggior parte dei pazienti aveva ricevuto un trattamento antivirale, ma non sempre nelle prime 48 ore, il che appare un fattore prognostico infausto. Così, il trattamento antivirale è consigliato nelle forme gravi; il virus pandemico A (H1N1) era sensibile ai due inibitori della neuraminidasi. Sono stati riscontrati dei casi sporadici di resistenza, il che spinge a sviluppare altre molecole attive sui virus influenzali.

Viral pneumonitis is increased in obese patients during the first wave of pandemic A(H1N1) 2009 virus

Introduction

There is conflicting data as to whether obesity is an independent risk factor for mortality in severe pandemic (H1N1) 2009 influenza (A(H1N1)pdm09). It is postulated that excess inflammation and cytokine production in obese patients following severe influenza infection leads to viral pneumonitis and/or acute respiratory distress syndrome.

Methods

Demographic, laboratory and clinical data prospectively collected from obese and non-obese patients admitted to nine adult Australian intensive care units (ICU) during the first A(H1N1)pdm09 wave, supplemented with retrospectively collected data, were compared.

Results

Of 173 patients, 100 (57.8%), 73 (42.2%) and 23 (13.3%) had body mass index (BMI) <30 kg/m², ≥30 kg/m² (obese) and ≥40 kg/m² (morbidly obese) respectively. Compared to non-obese patients, obese patients were younger (mean age 43.4 vs. 48.4 years, p = 0.035) and more likely to develop pneumonitis (61% vs. 44%, p = 0.029). Extracorporeal membrane oxygenation use was greater in morbidly obese compared to non-obese patients (17.4% vs. 4.7%, p = 0.04). Higher mortality rates were observed in non-obese compared to obese patients, but not after adjusting for severity of disease. C-reactive protein (CRP) levels and hospital length of stay (LOS) were similar. Amongst ICU survivors, obese patients had longer ICU LOS (median 11.9 vs. 6.8 days, p = 0.017). Similar trends were observed when only patients infected with A(H1N1)pdm09 were examined.

Conclusions

Among patients admitted to ICU during the first wave of A(H1N1)pdm09, obese and morbidly obese patients with severe infection were more likely to develop pneumonitis compared to non-obese patients, but mortality rates were not increased. CRP is not an accurate marker of pneumonitis.

Severe acute respiratory infections in the postpandemic era of H1N1

PURPOSE OF REVIEW

Shortly after the advent of severe acute respiratory syndrome and the avian influenza, the emergence of the influenza A(H1N1)2009 pandemic caused significant vibrations to the public health authorities and stressed the health systems worldwide. We sought to investigate whether this experience has altered our knowledge and our current and future practice on the management of severe acute respiratory infections (SARI) and community-acquired pneumonia.

RECENT FINDINGS

A changing epidemiology was demonstrated, with obesity and pregnancy beyond established risk groups for influenza A, other clinical syndromes beyond primary viral pneumonia, possible coinfections by other viral beyond bacterial pathogens and a disappointing performance of all available severity assessment tools. On the treatment topic, accumulating evidence suggesting worse outcomes argues against the use of corticosteroids, but some noninvasive ventilating modalities require further assessment.

SUMMARY

The recent influenza A(H1N1)2009 pandemic has highlighted our weaknesses relating to the diagnosis and assessment of severity of SARI, compromising early treatment and ultimate outcomes; further research based on this experience will help to improve prognosis and boost our future preparedness. An important message is the necessity of international collaboration for the rapid dissemination of locally acquired knowledge.

Comparison of clinical features and outcomes of hospitalized adult patients with novel influenza A (H1N1) pneumonia and other pneumonia

OBJECTIVES

A novel swine-origin influenza A (H1N1) virus caused worldwide outbreaks starting in April 2009. The aim of this study was to evaluate the clinical characteristics and outcomes of pandemic 2009 H1N1 pneumonia by comparing to community-acquired pneumonia (CAP) of other origin.

METHODS

The authors conducted a prospective cohort study of consecutive adult (over 15 years old) patients with suspected CAP requiring admission to a tertiary university-affiliated hospital during the second wave of pandemic 2009 H1N1 influenza. Based on the results of real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, the staff completed a standard assessment form and managed the patients according to a uniform protocol. Clinical characteristics, as well as laboratory and radiologic findings, were collected and compared between pandemic 2009 H1N1 pneumonia and CAP of other origin. The primary outcome was in-hospital mortality and secondary outcomes were duration of hospitalization, duration of intensive care unit (ICU) stay, and requirement of mechanical ventilation.

RESULTS

A total of 135 patients with suspected CAP were included in the study. Of these, 59 patients were RT-PCR positive for H1N1 virus, and 76 patients were RT-PCR negative. Patients with H1N1 pneumonia were significantly younger than those with CAP of other origin (46.0 years vs. 68.0 years, p < 0.01) and more frequently had nonspecific symptoms (p < 0.01), initial leukopenia (8.5% vs. 0.0%, p = 0.01), lymphopenia (45.8% vs. 26.3%, p = 0.02), low values of C-reactive protein (CRP; 5.2 mg/dL vs. 13.4 mg/dL, p = 0.02), bilateral abnormalities (57.7% vs. 29.7%, p < 0.01) on chest radiography, ground glass opacities (43.9% vs. 12.8%, p < 0.01) on chest computed tomography, and low values of pneumonia severity index (PSI) score (56.0 vs. 91.0, p < 0.01) than those with CAP of other origin. However, there were no significant differences in infection severity, clinical outcome, length of ICU stay, requirement for mechanical ventilation, and mortality between the two groups.

CONCLUSIONS

This study shows that clinical characteristics and outcomes of 2009 H1N1 pneumonia are comparable to those of CAP of other origin. However, some characteristics, including younger age, nonspecific symptoms (including headache, leukopenia, and fatigue), lymphopenia, lower initial CRP and PSI score, and radiologic findings (including bilateral abnormalities and ground glass opacities), may help clinicians to diagnostically differentiate between H1N1 pneumonia and CAP of other origin before the result of RT-PCR are obtained.

Biomarkers: what is their benefit in the identification of infection, severity assessment, and management of community-acquired pneumonia?

Biomarkers have been proposed as tools that can guide the management of patients with community-acquired pneumonia, providing information that supplements the usually available clinical data. Among the available biomarkers, procalcitonin has been studied extensively and seems promising for several purposes. The use of biomarkers needs further study, to validate their utility in daily practice, especially given the limitations of the current tools for identifying the need for antibiotic therapy in patients with influenza and secondary bacterial pneumonia, in patients with aspiration syndromes, and in those infected with atypical pathogens.

Non-specific inflammatory parameters in patients with pandemic H1N1 influenza

The measurement of non-specific inflammation parameters, such as erythrocyte sedimentation rate (ESR), fibrinogen, C-reactive protein (CRP) and procalctinon (PCT) are very important tools for diagnosis of infections, as well as for monitoring of treatment response. The aim of this study was to determine the significance of non-specific inflammatory parameters in patients with influenza H1N1 infection. ESR, fibrinogen, CRP and PCT were analyzed in patients with influenza H1N1 infection. The diagnosis of influenza H1N1 was established from the nasopharyngeal swabs using Real Time Polymerase Chain Reaction - (RT PCR) method. Chest X-ray was performed to diagnose pneumonia Sixty-three out of 340 hospitalized patients with influenza had pandemic influenza. Their mean age was 34.60±13.82 years. They were referred to hospital 1 to 7 (4.06±2.0) days after onset of symptoms. Of these, 46 had pneumonia, while the majority (41 patients) had interstitial pneumonia, and only five had lobar or segmental pneumonia. Patients with pneumonia had significantly higher levels of CRP and PCT in comparison with those without pneumonia. Patients with lobar pneumonia had significantly higher CRP than those with interstitial pneumonia. However, mean values of PCT between interstitial and lobar pneumonia cases did not differ significantly. Interstitial pneumonia was the most common complication of H1N1 infection among our patients. Non-specific parameters of inflammation, especially CRP and PCT were increased in all pneumonia cases, regardless of the etiology. Monitoring of non-specific inflammatory parameters in patients with H1N1 infection allows recognition of patients with complications, their prompt hospitalization and early initiation of antimicrobial therapy.

Do sepsis biomarkers in the emergency room allow transition from bundled sepsis care to personalized patient care?

PURPOSE OF REVIEW

There is convincing evidence linking early start of fluid resuscitation and initiation of appropriate antimicrobial therapy to improved outcomes in patients with sepsis in the emergency department. Blood biomarkers measured on admission and during follow-up have the ability to guide early sepsis recognition, severity assessment and therapeutic decisions in individual patients and may allow transition from bundled sepsis care to more individualized management in single patients.

RECENT FINDINGS

Although a large number of promising diagnostic and prognostic biomarkers have been put forward in observational studies, only few have been evaluated in prospective randomized-controlled intervention trials. Markers such as lactate for risk stratification and guidance of fluid resuscitation, procalcitonin for assessing risk of bacterial infections and guiding therapeutic decisions about initiation and duration of antimicrobial therapy, and recently proadrenomedullin for early mortality prediction and site-of-care decisions in respiratory infections, have shown to improve patient management.

SUMMARY

For few biomarkers, recent study results demonstrate that well defined clinical protocols have the potential to guide decisions about the individual risk stratification and treatment of patients with suspicion of sepsis ultimately leading to improved patient care and outcomes. For other biomarkers, promising observation data have been put forward, but their potential needs to be evaluated in large-scale, well designed prospective intervention studies before clinical use can be recommended.

A distinct influenza infection signature in the blood transcriptome of patients with severe community-acquired pneumonia

INTRODUCTION

Diagnosis of severe influenza pneumonia remains challenging because of a lack of correlation between the presence of influenza virus and clinical status. We conducted gene-expression profiling in the whole blood of critically ill patients to identify a gene signature that would allow clinicians to distinguish influenza infection from other causes of severe respiratory failure, such as bacterial pneumonia, and noninfective systemic inflammatory response syndrome.

METHODS

Whole-blood samples were collected from critically ill individuals and assayed on Illumina HT-12 gene-expression beadarrays. Differentially expressed genes were determined by linear mixed-model analysis and overrepresented biological pathways determined by using GeneGo MetaCore.

RESULTS

The gene-expression profile of H1N1 influenza A pneumonia was distinctly different from those of bacterial pneumonia and systemic inflammatory response syndrome. The influenza gene-expression profile is characterized by upregulation of genes from cell-cycle regulation, apoptosis, and DNA-damage-response pathways. In contrast, no distinctive gene-expression signature was found in patients with bacterial pneumonia or systemic inflammatory response syndrome. The gene-expression profile of influenza infection persisted through 5 days of follow-up. Furthermore, in patients with primary H1N1 influenza A infection in whom bacterial co-infection subsequently developed, the influenza gene-expression signature remained unaltered, despite the presence of a superimposed bacterial infection.

CONCLUSIONS

The whole-blood expression-profiling data indicate that the host response to influenza pneumonia is distinctly different from that caused by bacterial pathogens. This information may speed the identification of the cause of infection in patients presenting with severe respiratory failure, allowing appropriate patient care to be undertaken more rapidly.

Can procalcitonin tests aid in identifying bacterial infections associated with influenza pneumonia? A systematic review and meta-analysis

OBJECTIVE

To summarize evidence for the diagnostic accuracy of procalcitonin (PCT) tests for identifying secondary bacterial infections in patients with influenza.

METHODS

Major databases, including MEDLINE, EMBASE, and the Cochrane Library, were searched for studies published between January 1966 and May 2009 that evaluated PCT as a marker for diagnosing bacterial infections in patients with influenza infections and that provided sufficient data to construct two-by-two tables.

RESULTS

Six studies were selected that included 137 cases with bacterial coinfection and 381 cases without coinfection. The area under a summary ROC curve was 0·68 (95% CI: 0·64-0·72). The overall sensitivity and specificity estimates for PCT tests were 0·84 (95% CI: 0·75-0·90) and 0·64 (95% CI: 0·58-0·69), respectively. These studies reported heterogeneous sensitivity estimates ranging from 0·74 to 1·0. The positive likelihood ratio for PCT (LR+ = 2·31; 95% CI: 1·93-2·78) was not sufficiently high for its use as a rule-in diagnostic tool, while its negative likelihood ratio was reasonably low for its use as a rule-out diagnostic tool (LR- = 0·26; 95% CI: 0·17-0·40).

CONCLUSIONS

Procalcitonin tests have a high sensitivity, particularly for ICU patients, but a low specificity for identifying secondary bacterial infections among patients with influenza. Because of its suboptimal positive likelihood ratio and good negative likelihood ratio, it can be used as a suitable rule-out test but cannot be used as a standalone rule-in test.