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

Ultrasensitive Love-SAW Biosensor Based on Self-Assembled DMSN@AuNPs with In Situ Amplification for Detecting Biomarker Procalcitonin in Exhaled Breath Condensate

The COVID-19 pandemic has highlighted the importance of early screening and pathogen identification for the effective treatment of pneumonia. Exhaled breath condensate (EBC) provides a noninvasive and easily accessible method for early diagnosis of respiratory diseases, as it captures biomarkers from the airway lining fluid, offering a timely and reliable reflection of respiratory inflammation. Procalcitonin (PCT) is a biomarker widely used to assess infection type and severity, particularly for distinguishing between bacterial and nonbacterial pneumonia. However, detecting PCT especially in EBC is challenging due to its extremely low concentrations. In this work, we developed an ultrasensitive Love-type surface acoustic wave (Love-SAW) biosensor based on self-assembled gold nanoparticles on dendritic mesoporous silica nanoparticles (DMSN@AuNPs) with in situ amplification for PCT detection in EBC. Dendritic mesoporous silica nanoparticles (DMSNs), an emerging porous material with features of large surface area, high thermal stability, and ease of functionalization were employed to load a large amount of AuNPs that can spontaneously grow in situ to further enhance the sensing performance. An automatic detection system was also developed to integrate with the Love-SAW biosensor for multichannel detection of PCT in EBC for pneumonia screening. The DMSN@AuNPs based Love-SAW biosensor demonstrates remarkable performance with a detection range of 0.01-10 ng/mL and detection limit of 3.7 pg/mL, which is about 350 times higher than conventional AuNPs-based methods. These results validate the potential of DMSN@AuNPs based Love-SAW biosensors for ultrasensitive detection of low-concentration biomarkers, providing a promising platform for in vitro diagnostics.

Is There a Role for Bronchoscopy in Aspiration Pneumonia?

Aspiration represents the passage of oropharyngeal content to the lower respiratory tract. The interplay between the host and the aspirate proprieties determines the subsequent aspiration syndrome. A low pH, typical of gastric aspirate, favors chemical pneumonitis, whereas an increased bacterial inoculum causes aspiration pneumonia. About a quarter of patients with aspiration pneumonitis will develop a bacterial superinfection during the course of recovery. While antibiotic therapy is indicated for aspiration pneumonia, supportive care remains the cornerstone of treatment in aspiration pneumonitis. However, the overlapping clinical features of these syndromes lead to initiation of antimicrobial therapy in most cases of aspiration. Bronchoscopy can aid in clinical decision-making by direct airway visualization and also by providing access to a series of emerging biomarkers. Invasive microbiological studies increase diagnostic yield and enable a tailored antibiotic treatment. In conjunction with stewardship programs, invasive sampling and novel molecular diagnostics can decrease the amount of inappropriate antibiotic therapy. In the context of foreign body aspiration, bronchoscopy represents both diagnostic and treatment gold standard.

Diagnostic and Prognostic Roles of Procalcitonin and Other Tools in Community-Acquired Pneumonia: A Narrative Review

Community-acquired pneumonia (CAP) is among the most common causes of death and one of the leading healthcare concerns worldwide. It can evolve into sepsis and septic shock, which have a high mortality rate, especially in critical patients and comorbidities. The definitions of sepsis were revised in the last decade as "life-threatening organ dysfunction caused by a dysregulated host response to infection". Procalcitonin (PCT), C-reactive protein (CRP), and complete blood count, including white blood cells, are among the most commonly analyzed sepsis-specific biomarkers also used in pneumonia in a broad range of studies. It appears to be a reliable diagnostic tool to expedite care of these patients with severe infections in the acute setting. PCT was found to be superior to most other acute phase reactants and indicators, including CRP as a predictor of pneumonia, bacteremia, sepsis, and poor outcome, although conflicting results exist. In addition, PCT use is beneficial to judge timing for the cessation of antibiotic treatment in most severe infectious states. The clinicians should be aware of strengths and weaknesses of known and potential biomarkers in expedient recognition and management of severe infections. This manuscript is intended to present an overview of the definitions, complications, and outcomes of CAP and sepsis in adults, with special regard to PCT and other important markers.

Biomarkers for Lipid and Albumin Metabolism in Hospitalized Patients with Underlying Diseases and Community-Acquired Pneumonia Caused by Bacterial or SARS-CoV-2 Infection

Background

To look at the differences and similarities in albumin and lipid metabolism in non-severe COVID-19 infection, non-severe community-acquired pneumonia, and severe community pneumonia with underlying diseases, as well as the relationship between albumin and lipid metabolism and inflammatory mediators.

Methods

This retrospective analysis comprised 253 individuals with bacterial pneumonia and COVID-19 infection (1 May 2021-1 May 2022). Routine blood examination, blood lipid levels, albumin level, C-reactive protein (CRP) levels, coagulation function, cardiac enzymes, liver function, renal function, immunological function, and bacterial culture were also collected. Correlation analysis was performed using Spearman's test for lipid parameter and Inflammatory factors in the blood. Furthermore, the multiple linear regression (MLR) analysis was employed to analyze the multicollinearity in lipidomics data. The statistical analysis was performed using SPSS statistic version 19.0.

Results

There were 63 (24.90%) non-severe community-acquired pneumonia patients (NSCAP), 48 (18.97%) severe community-acquired pneumonia patients (SCAP), 112 (44.27%) non-severe COVID-19 infection patients (NSCOV), and 30 (11.86%) healthy volunteers (HV). In all, 45.59% (116/253) of the patients had underlying diseases. Patients with community-acquired pneumonia had lower albumin and cholesterol levels than those with non-severe COVID-19 infection and healthy controls (t = -3.81, -2.09, P = 0.00, 0.04). Albumin, triglyceride, cholesterol, and LDL-C levels in peripheral blood were considerably lower in the SCAP group than in the NSCAP group. Albumin, cholesterol, HDL-C, LDL-C, and aop-A were all inversely connected with CRP in the SCAP with underlying illness group, but cholesterol level was favorably correlated with lymphocyte count (R = 0.36, P = 0.01). Hypoproteinemia, hypotriglyceridemia, and an elevated neutrophil-to-lymphocyte count ratio are all risk factors for severe community-acquired pneumonia.

Conclusion

Hypoalbuminemia and abnormal lipid metabolism are important indicators of bacterial infection, especially severe bacterial pneumonia.

Which children with chest-indrawing pneumonia can be safely treated at home, and under what conditions is it safe to do so? A systematic review of evidence from low- and middle-income countries

Background

WHO pneumonia guidelines recommend that children (aged 2-59 months) with chest indrawing pneumonia and without any "general danger sign" can be treated with oral amoxicillin without hospital admission. This recommendation was based on trial data from limited contexts whose generalisability is unclear. This review aimed to identify which children with chest-indrawing pneumonia in low- and middle-income countries can be safely treated at home, and under what conditions is it safe to do so.

Methods

We searched MEDLINE, EMBASE, and PubMed for observational and interventional studies of home-based management of children (aged 28 days to four years) with chest-indrawing pneumonia in low- or middle-income countries.

Results

We included 14 studies, including seven randomised trials, from a variety of urban and rural contexts in 11 countries. Two community-based and two hospital-based trials in Pakistan and India found that home treatment of chest-indrawing pneumonia was associated with similar or superior treatment outcomes to hospital admission. Evidence from trials (n = 3) and observational (n = 6) studies in these and other countries confirms the acceptability and feasibility of home management of chest-indrawing pneumonia in low-risk cases, so long as safeguards are in place. Risk assessment includes clinical danger signs, oxygen saturation, and the presence of comorbidities such as undernutrition, anaemia, or HIV. Pulse oximetry is a critical risk-assessment tool that is currently not widely available and can identify severely ill patients with hypoxaemia otherwise possibly missed by clinical assessment alone. Additional safeguards include caregiver understanding and ability to return for review.

Conclusions

Home treatment of chest-indrawing pneumonia can be safe but should only be recommended for children confirmed to be low-risk and in contexts where appropriate care and safety measures are in place.

Community-Acquired Pneumonia

Community-acquired pneumonia is an important cause of morbidity and mortality. It can be caused by bacteria, viruses, or fungi and can be prevented through vaccination with pneumococcal, influenza, and COVID-19 vaccines. Diagnosis requires suggestive history and physical findings in conjunction with radiographic evidence of infiltrates. Laboratory testing can help guide therapy. Important issues in treatment include choosing the proper venue, timely initiation of the appropriate antibiotic or antiviral, appropriate respiratory support, deescalation after negative culture results, switching to oral therapy, and short treatment duration.

Plasma lipid profiling for the prognosis of 90-day mortality, in-hospital mortality, ICU admission, and severity in bacterial community-acquired pneumonia (CAP)

Introduction

Pneumonia is the most common cause of mortality from infectious diseases, the second leading cause of nosocomial infection, and the leading cause of mortality among hospitalized adults. To improve clinical management, metabolomics has been increasingly applied to find specific metabolic biopatterns (profiling) for the diagnosis and prognosis of various infectious diseases, including pneumonia.

Methods

One hundred fifty bacterial community-acquired pneumonia (CAP) patients whose plasma samples were drawn within the first 24 h of hospital admission were enrolled in this study and separated into two age- and sex-matched cohorts: non-survivors (died ≤ 90 days) and survivors (survived > 90 days). Three analytical tools, ¹H-NMR spectroscopy, GC-MS, and targeted DI-MS/MS, were used to prognosticate non-survivors from survivors by means of metabolic profiles.

Results

We show that quantitative lipid profiling using DI-MS/MS can predict the 90-day mortality and in-hospital mortality among patients with bacterial CAP compared to ¹H-NMR- and GC-MS-based metabolomics. This study showed that the decreased lysophosphatidylcholines and increased acylcarnitines are significantly associated with increased mortality in bacterial CAP. Additionally, we found that decreased lysophosphatidylcholines and phosphatidylcholines (> 36 carbons) and increased acylcarnitines may be used to predict the prognosis of in-hospital mortality for bacterial CAP as well as the need for ICU admission and severity of bacterial CAP.

Discussion

This study demonstrates that lipid-based plasma metabolites can be used for the prognosis of 90-day mortality among patients with bacterial CAP. Moreover, lipid profiling can be utilized to identify patients with bacterial CAP who are at the highest risk of dying in hospital and who need ICU admission as well as the severity assessment of CAP.

2018 recommendations for the management of community acquired pneumonia

Community-acquired pneumonia (CAP) is the leading cause of death worldwide. Despite the vast diversity of respiratory microbiota, Streptococcus pneumoniae remains the most prevalent pathogen among etiologic agents. Despite the significant decrease in the mortality rates for lower respiratory tract infections in recent decades, CAP ranks third as a cause of death in Brazil. Since the latest Guidelines on CAP from the Sociedade Brasileira de Pneumologia e Tisiologia (SBPT, Brazilian Thoracic Association) were published (2009), there have been major advances in the application of imaging tests, in etiologic investigation, in risk stratification at admission and prognostic score stratification, in the use of biomarkers, and in the recommendations for antibiotic therapy (and its duration) and prevention through vaccination. To review these topics, the SBPT Committee on Respiratory Infections summoned 13 members with recognized experience in CAP in Brazil who identified issues relevant to clinical practice that require updates given the publication of new epidemiological and scientific evidence. Twelve topics concerning diagnostic, prognostic, therapeutic, and preventive issues were developed. The topics were divided among the authors, who conducted a nonsystematic review of the literature, but giving priority to major publications in the specific areas, including original articles, review articles, and systematic reviews. All authors had the opportunity to review and comment on all questions, producing a single final document that was approved by consensus.

An Interferon Signature Discriminates Pneumococcal From Staphylococcal Pneumonia

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia (CAP). Despite the low prevalence of CAP caused by methicillin-resistant Staphylococcus aureus (MRSA), CAP patients often receive empirical antibiotic therapy providing coverage for MRSA such as vancomycin or linezolid. An early differentiation between S. pneumoniae and S. aureus pneumonia can help to reduce the use of unnecessary antibiotics. The objective of this study was to identify candidate biomarkers that can discriminate pneumococcal from staphylococcal pneumonia. A genome-wide transcriptional analysis of lung and peripheral blood performed in murine models of S. pneumoniae and S. aureus lung infection identified an interferon signature specifically associated with S. pneumoniae infection. Prediction models built using a support vector machine and Monte Carlo cross-validation, identified the combination of the interferon-induced chemokines CXCL9 and CXCL10 serum concentrations as the set of biomarkers with best sensitivity, specificity, and predictive power that enabled an accurate discrimination between S. pneumoniae and S. aureus pneumonia. The predictive performance of these biomarkers was further validated in an independent cohort of mice. This study highlights the potential of serum CXCL9 and CXCL10 biomarkers as an adjunctive diagnostic tool that could facilitate prompt and correct pathogen-targeted therapy in CAP patients.

The prognostic and risk-stratified value of neutrophil–lymphocyte count ratio in Chinese patients with community-acquired pneumonia

Community-acquired pneumonia is a common disease associated with high mortality. This retrospective study examined whether the neutrophil–lymphocyte count ratio (NLR), already widely used as an index of inflammation, can be used to predict in-hospital mortality of adults with community-acquired pneumonia. Clinical characteristics, CURB-65 and pneumonia severity index score of pneumonia severity, NLR, serum levels of C-reactive protein and procalcitonin, and in-hospital mortality were analyzed for 318 consecutive adults with community-acquired pneumonia admitted to West China Hospital between July 2012 and December 2013. The ability of NLR and other parameters to predict in-hospital mortality was assessed using receiver operating characteristic (ROC) curves. Results showed that NLR increased with increasing CURB-65 ( P < 0.05) and pneumonia severity index ( P < 0.05), and NLR correlated positively with serum levels of C-reactive protein (r = 0.239, P < 0.05) and procalcitonin (r = 0.211, P < 0.05). The median value of NLR was significantly higher among patients who died in hospital (11.96) than among those who were alive at the end of hospitalization (4.19, P < 0.05). Based on a cut-off NLR of 7.12, this index predicted in-hospital mortality with a sensitivity of 82.61% and specificity of 72.20% (area under ROC curve, 0.799). Predictive power was greater for the combination of NLR and serum levels of C-reactive protein and procalcitonin. These results suggest that NLR may be useful for predicting prognosis in Chinese adults with community-acquired pneumonia, and it may work better in combination with traditional markers.

Economic evaluation of procalcitonin-guided antibiotic therapy in acute respiratory infections: a Chinese hospital system perspective

Background:

Cost-impact models have indicated that in the USA, the use of antibiotic stewardship protocols based on procalcitonin (PCT) levels for patients with suspected acute respiratory tract infection results in cost savings. Our objective was to assess the cost impact of adopting PCT testing among patients with acute respiratory infections (ARI) from the perspective of a typical hospital system in urban China.

Methods:

To conduct an economic evaluation of PCT testing versus usual care we built a cost-impact model based on a previously published patient-level meta-analysis data of randomized trials including Chinese sites. The data were adapted to the China setting by applying the results to mean lengths of stay, costs, and practice patterns typically found in China. We estimated the annual ARI visit rate for the typical hospital system (assumed to be 1650 beds) and ARI diagnosis.

Results:

In the inpatient setting, the costs of PCT-guided care compared to usual care for a cohort of 16,405 confirmed ARI patients was almost 1.1 million Chinese yuan (CNY), compared to almost 1.8 million CNY for usual care, resulting in net savings of 721,563 CNY to a typical urban Chinese hospital system for 2015. In the ICU and outpatient settings, savings were 250,699 CNY and 2.4 million CNY, respectively. The overall annual net savings of PCT-guided care was nearly 3.4 million CNY.

Conclusions:

Substantial savings are associated with PCT protocols of ARI across common China hospital treatment settings mainly by direct reduction in unnecessary antibiotic utilization.

HDL-c levels predict the presence of pleural effusion and the clinical outcome of community-acquired pneumonia

Objectives

To investigate if HDL cholesterol (HDL-c) could be a biomarker of the degree of severity according to prognostic prediction scores in community-acquired pneumonia (CAP) or the development of clinical complications such as pleural effusion.

Methods

We included in a retrospective study 107 patients admitted to the hospital that fulfilled diagnostic criteria for CAP between the 30th October 2011 and 1st September 2012. HDL-c levels at admission, CAP prognosis scores (PSI and CURB65) and clinical outcomes were recorded for the study.

Results

Basal HDL-c levels were not statistically different according to prognostics scores neither PSI nor CURB-65. Significantly lower levels of HDL-c were also associated to the development of septic shock and admission to the intensive care unit. HDL-c were inversely correlated with acute phase reactants CRP (r = −0.585, P < 0.001), ESR (r = −0.477, P < 0.001), and leukocytes cell count (r = −0.254, P < 0.009). Patients with pleural effusion showed significant lower levels of HDL-c [28.9 (15.5) mg/dl vs. 44.6 (21.1) mg/dl]; P = 0.007. HDL-c is a good predictor of the presence of pleural effusion in multivariate analyses and using ROC analyses [AUC = 0.712 (0.591–0.834), P = 0.006]. HDL-c levels of 10 mg/dl showed a sensitivity of 97.6 % and a specificity of 82.4 % for the presence of pleural effusion.

Conclusion

Monitoring HDL-c in CAP is an useful serum marker of acute phase response, clinical outcome and the presence of pleural effusion.

Lipid metabolites as potential diagnostic and prognostic biomarkers for acute community acquired pneumonia

Early diagnosis of acute community-acquired pneumonia (CAP) is important in patient triage and treatment decisions. To identify biomarkers that distinguish patients with CAP from non-CAP controls, we conducted an untargeted global metabolome analysis for plasma samples from 142 patients with CAP (CAP cases) and 97 without CAP (non-CAP controls). Thirteen lipid metabolites could discriminate between CAP cases and non-CAP controls with area-under-the-receiver-operating-characteristic curve of >0.8 (P ≤ 10⁻⁹). The levels of glycosphingolipids, sphingomyelins, lysophosphatidylcholines and L-palmitoylcarnitine were higher, while the levels of lysophosphatidylethanolamines were lower in the CAP cases than those in non-CAP controls. All 13 metabolites could distinguish CAP cases from the non-infection, extrapulmonary infection and non-CAP respiratory tract infection subgroups. The levels of trihexosylceramide (d18:1/16:0) were higher, while the levels of lysophosphatidylethanolamines were lower, in the fatal than those of non-fatal CAP cases. Our findings suggest that lipid metabolites are potential diagnostic and prognostic biomarkers for CAP.

•

Thirteen lipid metabolites could discriminate CAP cases from non-CAP controls.

•

The levels of 2 lipid metabolites differ between fatal and non-fatal CAP cases.

•

Lipid metabolites are potential diagnostic and prognostic biomarkers for CAP.

Fluoroquinolone- and ceftriaxone-based therapy of community-acquired pneumonia in hospitalized patients: the risk of subsequent isolation of multidrug-resistant organisms

A retrospective cohort study was performed on 175 adult patients treated for community-acquired pneumonia with moxifloxacin or ceftriaxone/azithromycin in a nonintensive care unit. Both cohorts were very similar with regard to a wide range of characteristics including age, severity of disease, comorbidities, length of stay, and mortality. Multidrug-resistant organisms were subsequently isolated from 6 (15%) moxifloxacin-treated patients and 5 (4%) ceftriaxone/azithromycin-treated patients within 90 days after beginning of therapy (P = .026 on logistic regression analysis).

The Use of Procalcitonin in Clinical Practice

Procalcitonin (PCT) has emerged as the most promising marker of infectious inflammation. This development is critical to the practicing doctor dealing with febrile patients with suspected sepsis. An ideal biomarker would provide data for early diagnosis, differentiation of bacterial from non-bacterial causes of inflammation and information about the clinical course and prognosis of the disease. PCT is an early biomarker that is present within 3 to 4 hours of the triggering infection. An undetectable PCT level would efficiently rule out systemic infection. PCT may also be viewed as a marker of resolving infection as it has a half-life of about 22 hours, and its blood level correlates with bacterial load. Thus, PCT may be used as a clinical tool for early diagnosis, prognosis and therapeutic guide. Automated platforms with short assay times and service that is available 24 hours a day have enabled clinicians to obtain rapid reliable results for the early diagnosis and timely monitoring of appropriate pharmacotherapy. Clinicians should use PCT as an adjunct to clinical and other diagnostic criteria.

Diagnosis of pneumococcal pneumonia: current pitfalls and the way forward

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia. However, it can also asymptomatically colonize the upper respiratory tract. Because of the need to distinguish between S. pneumoniae that is simply colonizing the upper respiratory tract and S. pneumoniae that is causing pneumonia, accurate diagnosis of pneumococcal pneumonia is a challenging issue that still needs to be solved. Sputum Gram stains and culture are the first diagnostic step for identifying pneumococcal pneumonia and provide information on antibiotic susceptibility. However, these conventional methods are relatively slow and insensitive and show limited specificity. In the past decade, new diagnostic tools have been developed, particularly antigen (teichoic acid and capsular polysaccharides) and nucleic acid (ply, lytA, and Spn9802) detection assays. Use of the pneumococcal antigen detection methods along with biomarkers (C-reactive protein and procalcitonin) may enhance the specificity of diagnosis for pneumococcal pneumonia. This article provides an overview of current methods of diagnosing pneumococcal pneumonia and discusses new and future test methods that may provide the way forward for improving its diagnosis.

Antibiotic utilization for acute respiratory tract infections in U.S. emergency departments

Inappropriate use of antibiotics for acute respiratory tract infections (ARTIs) has decreased in many outpatient settings. For patients presenting to U.S. emergency departments (EDs) with ARTIs, antibiotic utilization patterns are unclear. We conducted a retrospective cohort study of ED patients from 2001 to 2010 using data from the National Hospital Ambulatory Medical Care Survey (NHAMCS). We identified patients presenting to U.S. EDs with ARTIs and calculated rates of antibiotic utilization. Diagnoses were classified as antibiotic appropriate (otitis media, sinusitis, pharyngitis, tonsillitis, and nonviral pneumonia) or antibiotic inappropriate (nasopharyngitis, unspecified upper respiratory tract infection, bronchitis or bronchiolitis, viral pneumonia, and influenza).There were 126 million ED visits with a diagnosis of ARTI, and antibiotics were prescribed in 61%. Between 2001 and 2010, antibiotic utilization decreased for patients aged<5 presenting with antibiotic-inappropriate ARTI (rate ratio [RR], 0.94; confidence interval [CI], 0.88 to 1.00). Utilization also decreased significantly for antibiotic-inappropriate ARTI patients aged 5 to 19 years (RR, 0.89; CI, 0.85 to 0.94). Utilization remained stable for antibiotic-inappropriate ARTI among adult patients aged 20 to 64 years (RR, 0.99; CI, 0.97 to 1.01). Among adults, rates of quinolone use for ARTI increased significantly from 83 per 1,000 visits in 2001 to 2002 to 105 per 1,000 in 2009 to 2010 (RR, 1.08; CI, 1.03 to 1.14). Although significant progress has been made toward reduction of antibiotic utilization for pediatric patients with ARTI, the proportion of adult ARTI patients receiving antibiotics in U.S. EDs is inappropriately high. Institution of measures to reduce inappropriate antibiotic use in the ED setting is warranted.