Utility of two biomarkers for directing care among patients with non-severe community-acquired pneumonia

Biomarkers for risk stratification and antibiotic stewardship in elderly patients

PURPOSE

Optimal treatment of infections in the elderly patients population is challenging because clinical symptoms and signs may be less specific potentially resulting in both, over- and undertreatment. Elderly patients also have a less pronounced immune response to infection, which may influence kinetics of biomarkers of infection.

METHODS

Within a group of experts, we critically reviewed the current literature regarding biomarkers for risk stratification and antibiotic stewardship in elderly patients with emphasis on procalcitonin (PCT).

RESULTS

The expert group agreed that there is strong evidence that the elderly patient population is particularly vulnerable for infections and due to ambiguity of clinical signs and parameters in the elderly, there is considerable risk for undertreatment. At the same time, however, this group of patients is particularly vulnerable for off-target effects from antibiotic treatment and limiting the use of antibiotics is therefore important. The use of infection markers including PCT to guide individual treatment decisions has thus particular appeal in geriatric patients. For the elderly, there is evidence that PCT is a valuable biomarker for assessing the risk of septic complications and adverse outcomes, and helpful for guiding individual decisions for or against antibiotic treatment. There is need for additional educational efforts regarding the concept of "biomarker-guided antibiotic stewardship" for health care providers caring for elderly patients.

CONCLUSION

Use of biomarkers, most notably PCT, has high potential to improve the antibiotic management of elderly patients with possible infection for improving both, undertreatment and overtreatment. Within this narrative review, we aim to provide evidence-based concepts for the safe and efficient use of PCT in elderly patients.

A literature review of severity scores for adults with influenza or community-acquired pneumonia - implications for influenza vaccines and therapeutics

Influenza vaccination and antiviral therapeutics may attenuate disease, decreasing severity of illness in vaccinated and treated persons. Standardized assessment tools, definitions of disease severity, and clinical endpoints would support characterizing the attenuating effects of influenza vaccines and antivirals. We review potential clinical parameters and endpoints that may be useful for ordinal scales evaluating attenuating effects of influenza vaccines and antivirals in hospital-based studies. In studies of influenza and community-acquired pneumonia, common physiologic parameters that predicted outcomes such as mortality, ICU admission, complications, and duration of stay included vital signs (hypotension, tachypnea, fever, hypoxia), laboratory results (blood urea nitrogen, platelets, serum sodium), and radiographic findings of infiltrates or effusions. Ordinal scales based on these parameters may be useful endpoints for evaluating attenuating effects of influenza vaccines and therapeutics. Factors such as clinical and policy relevance, reproducibility, and specificity of measurements should be considered when creating a standardized ordinal scale for assessment.

Where is Chlamydophila pneumoniae pneumonia?

BACKGROUND

Molecular diagnostic methods have recently gained widespread use, and consequently, the importance of viral pathogens in community-acquired pneumonia (CAP) has undergone re-evaluation. Under these circumstances, the role of Chlamydophila pneumoniae as a pathogen that causes CAP also needs to be reviewed.

METHODS

We reviewed articles that contained data on the frequency of identification of C. pneumoniae pneumonia as a causative pathogen for CAP. The articles were identified by performing a search in PubMed with the keywords "community-acquired pneumonia" and "pathogen".

RESULTS

Sixty-three articles were identified. The reviewed articles demonstrated that the rates of identification of C. pneumoniae as the causative pathogen for CAP were significantly lower in assessments based on polymerase chain reaction (PCR) methods than in those based on serological methods. In some studies, it was possible to compare both serological and PCR methods directly using the same set of samples.

CONCLUSIONS

The use of PCR methods, including multiplex PCR assays, has revealed that C. pneumoniae may play a limited role as a pathogen for CAP.

Blood circRNAs as biomarkers for the diagnosis of community-acquired pneumonia

Circular RNAs (circRNAs) have been reported as effective diagnostic and therapeutic biomarkers in many diseases, but the potential of using this easy-to-monitor and highly stable materials for diagnosing Community-acquired pneumonia (CAP) remains unexplored. Here, aiming to identify potential CAP-related circRNAs in peripheral blood and seeking to deepen the understanding of how circRNA-miRNA-mRNA regulatory networks may contribute to CAP, we applied microarrays profiling analysis and identified 8296 differentially expressed (DE) circRNAs between patients with CAP (n = 6) and healthy controls (n = 6). Subsequently, we validated the accumulation trends for the top 100 DE circRNAs based on qPCR in an independent validation cohort (30 patients vs 30 controls), and ultimately identified a panel of four circRNAs that perform extremely well as sensitive and specific biomarkers for diagnosing CAP: hsa_circ_0018429 (area under the curve [AUC] = 0.8216), hsa_circ_0026579 (AUC = 0.7733), hsa_circ_0125357 (AUC = 0.7730), and hsa_circ_0099188 (AUC = 0.6978); combined as a panel (AUC = 0.8776). In addition, hsa_circ_0026579 exhibited good performance in differentiating viral from bacterial or mixed infection, with an AUC of 0.863. We also identified 10 miRNAs that most likely to interact with these four circRNAs, and then predicted 205 mRNA target genes. The KEGG pathway enrichment analysis suggested highly plausible functional implications related to inflammation and to virus-infection-related signaling pathways (such as HTLV-1 infection and hepatitis B infection). Thus, we generated a genetic network of potential CAP-related regulatory interactions that should inform future hypothesis-driven research into the causes and potential treatment of this widespread and frequently fatal disease.

Comparison of procalcitonin, C-reactive protein, white blood cell count and clinical status in diagnosing pneumonia in patients hospitalized with acute exacerbations of COPD: A prospective observational study

Lower respiratory tract infection is the most common cause of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). The aim of the present study was to compare the accuracy of procalcitonin (PCT), C-reactive protein (CRP) and white blood cell count (WBC) as single diagnostic tests and in combination with clinical signs and symptoms to diagnose pneumonia in patients hospitalized with AECOPD. This was a prospective, single centre observational study. Patients with spirometry-confirmed COPD who were hospitalized due to AECOPD were consecutively recruited at the hospital's Emergency Unit. Pneumonia was defined as a new pulmonary infiltrate on chest X-ray. The values of PCT, CRP and WBC were determined at admission. Receiver operating characteristic (ROC) curve analysis was used to study the accuracy of various diagnostic tests. Of the 113 included patients, 35 (31%) had pneumonia at admission. Area under the ROC curve (AUC) for PCT, CRP and WBC as a single test to distinguish between patients with and without pneumonia was 0.67 (95% CI 0.55-0.79), 0.73 (95% CI 0.63-0.84) and 0.67 (95% CI 0.55-0.79), respectively ( p = 0.42 for the test of difference). The AUC for a model of clinical signs and symptoms was 0.84 (95% CI 0.76-0.92). When biomarkers were added to the clinical model, the AUCs of the combined models were not significantly different from that of the clinical model alone ( p = 0.54). PCT had about the same accuracy as CRP and WBC in predicting pneumonia in patients hospitalized with AECOPD both as a single test and in combination with clinical signs and symptoms.

Usefulness and prognostic value of biomarkers in patients with community-acquired pneumonia in the emergency department

Between all patients treated in the Emergency Department (ED), 1.35% are diagnosed with community-acquired pneumonia (CAP). CAP is the main cause of death due to infectious disease (10-14%) and the most frequent reason of sepsis-septic shock in the ED. In the last decade, the search for objective tools to help establishing an early diagnosis, bacterial aetiology, severity, suspicion of bacteremia and the prognosis of mortality has increased. Biomarkers have shown their usefulness in this matter. Procalcitonin (obtains the highest accuracy for CAP diagnosis, bacterial aetiology and the presence of bacteremia), lactate (biomarker of hypoxia and tissue hypoperfusion) and proadrenomedullin (which has the greatest accuracy to predict mortality which in combination with the prognostic severity scales obtains even better results). The aim of this review is to highlight recently published scientific evidence and to compare the utility and prognostic accuracy of the biomarkers in CAP patients treated in the ED.

Identification of miRNA biomarkers of pneumonia using RNA-sequencing and bioinformatics analysis

Pneumonia is a lower respiratory tract infection that causes dramatic mortality worldwide. The present study aimed to investigate the pathogenesis of pneumonia and identify microRNA (miRNA) biomarkers as candidates for targeted therapy. RNA from the peripheral blood plasma of participants with pneumonia (severe, n=9; non-severe, n=9) and controls (n=9) was isolated and paired-end sequencing was performed on an Illumina HiSeq4000 system. Following the processing of raw reads, the sequences were aligned against the Genome Reference Consortium human genome assembly 38 reference genome using Bowtie2 software. Reads per kilobase of transcript per million mapped read values were obtained and the limma software package was used to identify differentially expressed miRNAs (DE-miRs). Then, DE-miR targets were predicted and subjected to enrichment analysis. In addition, a protein-protein interaction (PPI) network of the predicted targets was constructed. This analysis identified 11 key DE-miRs in pneumonia samples, including 6 upregulated miRNAs (including hsa-miR-34a and hsa-miR-455) and 5 downregulated miRNAs (including hsa-let-7f-1). All DE-miRs kept their upregulation/downregulation pattern in the control, non-severe pneumonia and severe pneumonia samples. Predicted target genes of DE-miRs in the subjects with non-severe pneumonia vs. the control and the subjects with severe pneumonia vs. the non-severe pneumonia group were markedly enriched in the adherens junction and Wnt signaling pathways. KALRN, Ras homolog family member A (RHOA), β-catenin (CTNNB1), RNA polymerase II subunit K (POLR2K) and amyloid precursor protein (APP) were determined to encode crucial proteins in the PPI network constructed. KALRN was predicted to be a target of hsa-mir-200b, while RHOA, CTNNB1, POLR2K and APP were predicted targets of hsa-let-7f-1. The results of the present study demonstrated that hsa-let-7f-1 may serve a role in the development of cancer and the Notch signaling pathway. Conversely, hsa-miR-455 may be an inhibitor of pneumonia pathogenesis. Furthermore, hsa-miR-200b might promote pneumonia via targeting KALRN.

Tools for outcome prediction in patients with community acquired pneumonia

INTRODUCTION

Community-acquired pneumonia (CAP) is one of the most common causes of mortality world-wide. The mortality rate of patients with CAP is influenced by the severity of the disease, treatment failure and the requirement for hospitalization and/or intensive care unit (ICU) management, all of which may be predicted by biomarkers and clinical scoring systems. Areas covered: We review the recent literature examining the efficacy of established and newly-developed clinical scores, biological and inflammatory markers such as C-Reactive protein (CRP), procalcitonin (PCT) and Interleukin-6 (IL-6), whether used alone or in conjunction with clinical severity scores to assess the severity of CAP, predict treatment failure, guide acute in-hospital or ICU admission and predict mortality. Expert commentary: The early prediction of treatment failure using clinical scores and biomarkers plays a developing role in improving survival of patients with CAP by identifying high-risk patients requiring hospitalization or ICU admission; and may enable more efficient allocation of resources. However, it is likely that combinations of scoring systems and biomarkers will be of greater use than individual markers. Further larger studies are needed to corroborate the additive value of these markers to clinical prediction scores to provide a safer and more effective assessment tool for clinicians.

Prevalence of Atypical Pathogens in Patients With Cough and Community-Acquired Pneumonia: A Meta-Analysis

PURPOSE

Community-acquired pneumonia (CAP), acute cough, bronchitis, and lower respiratory tract infections (LRTI) are often caused by infections with viruses or Streptococcus pneumoniae. The prevalence of atypical pathogens Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, and Bordetella pertussis among patients with these illnesses in the ambulatory setting has not been previously summarized. We set out to derive prevalence information from the existing literature.

METHODS

We performed a systematic review of MEDLINE for prospective, consecutive-series studies reporting the prevalence of M pneumoniae, C pneumoniae, L pneumophila and/or B pertussis in outpatients with cough, acute bronchitis, LRTI, or CAP. Articles were independently reviewed by 2 authors for inclusion and abstraction of data; discrepancies were resolved by consensus discussion. A meta-analysis was performed on each pathogen to calculate the pooled prevalence estimates using a random effects model of raw proportions.

RESULTS

Fifty studies met our inclusion criteria. While calculated heterogeneity was high, most studies reported prevalence for each pathogen within a fairly narrow range. In patients with CAP, the overall prevalences of M pneumoniae and C pneumoniae were 10.1% (95% CI, 7.1%-13.1%) and 3.5% (95% CI, 2.2%-4.9%), respectively. Consistent with previous reports, M pneumoniae prevalence peaked in roughly 6-year intervals. Overall prevalence of L pneumophila was 2.7% (95% CI, 2.0%-3.4%), but the organism was rare in children, with only 1 case in 1,765. In patients with prolonged cough in primary care, the prevalence of B pertussis was 12.4% (95% CI, 4.9%-19.8%), although it was higher in studies that included only children (17.6%; 95% CI, 3.4%-31.8%).

CONCLUSIONS

Atypical bacterial pathogens are relatively common causes of lower respiratory diseases, including cough, bronchitis, and CAP. Where surveillance data were available, we found higher prevalences in studies where all patients are tested for these pathogens. It is likely that these conditions are underreported, underdiagnosed, and undertreated in current clinical practice.

Host Biomarkers for Distinguishing Bacterial from Non-Bacterial Causes of Acute Febrile Illness: A Comprehensive Review

Background

In resource limited settings acute febrile illnesses are often treated empirically due to a lack of reliable, rapid point-of-care diagnostics. This contributes to the indiscriminate use of antimicrobial drugs and poor treatment outcomes. The aim of this comprehensive review was to summarize the diagnostic performance of host biomarkers capable of differentiating bacterial from non-bacterial infections to guide the use of antibiotics.

Methods

Online databases of published literature were searched from January 2010 through April 2015. English language studies that evaluated the performance of one or more host biomarker in differentiating bacterial from non-bacterial infection in patients were included. Key information extracted included author information, study methods, population, pathogens, clinical information, and biomarker performance data. Study quality was assessed using a combination of validated criteria from the QUADAS and Lijmer checklists. Biomarkers were categorized as hematologic factors, inflammatory molecules, cytokines, cell surface or metabolic markers, other host biomarkers, host transcripts, clinical biometrics, and combinations of markers.

Findings

Of the 193 citations identified, 59 studies that evaluated over 112 host biomarkers were selected. Most studies involved patient populations from high-income countries, while 19% involved populations from low- and middle-income countries. The most frequently evaluated host biomarkers were C-reactive protein (61%), white blood cell count (44%) and procalcitonin (34%). Study quality scores ranged from 23.1% to 92.3%. There were 9 high performance host biomarkers or combinations, with sensitivity and specificity of ≥85% or either sensitivity or specificity was reported to be 100%. Five host biomarkers were considered weak markers as they lacked statistically significant performance in discriminating between bacterial and non-bacterial infections.

Discussion

This manuscript provides a summary of host biomarkers to differentiate bacterial from non-bacterial infections in patients with acute febrile illness. Findings provide a basis for prioritizing efforts for further research, assay development and eventual commercialization of rapid point-of-care tests to guide use of antimicrobials. This review also highlights gaps in current knowledge that should be addressed to further improve management of febrile patients.

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.

Multimarker Prognostication for Hospitalized Patients with Community-acquired Pneumonia

OBJECTIVE

The optimal prognostic model for community-acquired pneumonia (CAP) remains unclear. In this study, we sought to identify independent predictors of 30-day mortality in patients with CAP and to determine whether adding specific prognostic factors to each of the two clinical prediction scores could improve the prognostic yield.

METHODS

This retrospective study involved 797 CAP patients who had been hospitalized at a tertiary referral center. The patients were categorized into two groups: those who survived and those who had died on or before 30 days after admission. Select clinical parameters were then compared between the two groups.

RESULTS

During the 30-day period, there were 72 deaths (9%). We constructed two models for a multivariate analysis: one was based on a high CURB-65 score (3-5) and the other on a high pneumonia severity index (PSI) class (V). In both models, a high CURB-65 score or a high PSI class, along with the presence of dyspnea, high Eastern Cooperative Oncology Group (ECOG) performance status (3-4), and a low serum albumin level, were independent predictors of 30-day mortality. In both the CURB-65-based and PSI-based models, the addition of dyspnea, high ECOG performance status, and hypoalbuminemia (<3 g/dL) enhanced the prognostic assessment, and subsequently, the c-statistics calculated with the use of three- or four- predictor combinations exceeded 0.8.

CONCLUSION

In addition to the CURB-65 or PSI, the clinical factors of dyspnea, the ECOG performance status, and serum albumin level may be independent predictors of 30-day mortality in CAP patients. When combined with the CURB-65 or PSI, these parameters provide additional evidence for predicting poor prognoses.

Management of patients with respiratory infections in primary care: procalcitonin, C-reactive protein or both?

Use of inflammatory biomarkers to guide antibiotic decisions has shown promising results in the risk-adapted management of respiratory tract infections, mainly in the inpatient setting. Several observational and interventional trials have investigated the benefits of procalcitonin (PCT) and C-reactive protein (CRP) testing in primary care. Both markers have shown promising results, although CRP is an inflammatory biomarker while PCT is more specific for bacterial infections. For CRP, point-of-care testing is widely established. Recently, sensitive point-of-care testing for PCT has also become available. A high-quality trial comparing these two markers for the management of patients in primary care is currently lacking. The aim of this paper is to review the existing literature investigating the use of PCT and CRP in primary care. The authors compare their performance for guiding antibiotic stewardship and analyze the cut-off values and endpoints to put these parameters into context in a low-acuity environment.

Association of White Blood Cell Count and C-Reactive Protein with Outcomes in Children Hospitalized for Community-acquired Pneumonia

We examined the association between baseline peripheral white blood cell count and C-reactive protein (CRP) values with outcomes among 153 children hospitalized with pneumonia. In multivariable analyses, CRP, but not white blood cell count, was significantly associated with both fever duration and hospital length of stay. For every 1mg/dL increase in CRP, length of stay increased by 1 hour.

Major advances in managing community-acquired pneumonia

This article is a non-systematic review of selected recent publications in community-acquired pneumonia, including a comparison of various guidelines. Risk stratification of patients has recently been advanced by the addition of several useful biomarkers. The issue of single versus dual antibiotic treatment remains controversial and awaits a conclusive randomized controlled trial. However, in the meantime, there is a working consensus that more severe patients should receive dual therapy.

Markers of lower respiratory tract infections in emergency departments

Background

Acute respiratory tract infections are the common causes for admission to emergency department. Appropriate diagnosis and initiating treatment on time are important for reducing morbidity and mortality rate due to lower respiratory tract infection (LRTI). The aim of this study is to determine if C-reactive protein (CRP) levels and white blood cells (WBC) count are considerable markers to help rapid diagnosis and prediction of antibiotic need for lower respiratory infections in emergency departments. The relationships between infectious agents and those markers have also been evaluated.

Methods

Study subjects and control group were selected by defined criteria. Patients were analyzed and assessed for CRP and WBC, sputum Gram stain and culture besides routine laboratory tests and chest X-Rays.

Results

One hundred and ninety four episodes out of 175 patients were evaluated for the study. CRP level and WBC count were detected significantly higher in patients ofstudy group than in those of control group. Pseudomonas aeruginosa and Haemophilus influenzae were the pathogens most often isolated.

Conclusion

In conclusion, CRP and WBC sputum are important markers for diagnosis of LRTI at the emergency departments and results of microbiological analysis of respiratory specimens were correlated with these markers.

Trial registration

Registation number of ethic committee of Dr. Suat Seren Chest Diseases and Surgery Training and Research Hospital: 28.04.2006/114