Understanding the Host in the Management of Pneumonia. An Official American Thoracic Society Workshop Report

Smoking, Alcohol Use, Diabetes Mellitus, and Metabolic Syndrome as Risk Factors for Community-Acquired Pneumonia

Community-acquired pneumonia (CAP) continues to be a cause of significant morbidity and mortality worldwide. Much recent attention in this area of research has been focused on host factors associated with the infection. This article will discuss 4 diverse, yet often coexistent conditions, namely, smoking, excessive alcohol use, diabetes mellitus, and metabolic syndrome. While all these conditions can be considered to be largely associated with lifestyle factors, they represent important risk factors for CAP. All can lead to acquired host immune suppression that underlies their risk for the development of severe CAP.

A Review on Risk Factors, Traditional Diagnostic Techniques, and Biomarkers for Pneumonia Prognostication and Management in Diabetic Patients

People of all ages can contract pneumonia, and it can cause mild to severe disease and even death. In addition to being a major cause of death for elderly people and those with prior medical conditions such as diabetes, it isthe world's biggest infectious cause of death for children. Diabetes mellitus is a metabolic condition with a high glucose level and is a leading cause of lower limb amputation, heart attacks, strokes, blindness, and renal failure. Hyperglycemia is known to impair neutrophil activity, damage antioxidant status, and weaken the humoral immune system. Therefore, diabetic patients are more susceptible to pneumonia than people without diabetes and linked fatalities. The absence of quick, precise, simple, and affordable ways to identify the etiologic agents of community-acquired pneumonia has made diagnostic studies' usefulness contentious. Improvements in biological markers and molecular testing techniques have significantly increased the ability to diagnose pneumonia and other related respiratory infections. Identifying the risk factors for developing severe pneumonia and early testing in diabetic patients might lead to a significant decrease in the mortality of diabetic patients with pneumonia. In this regard, various risk factors, traditional testing techniques, and pathomechanisms are discussed in this review. Further, biomarkers and next-generation sequencing are briefly summarized. Finding biomarkers with the ability to distinguish between bacterial and viral pneumonia could be crucial because identifying the precise pathogen would stop the unnecessary use of antibiotics and effectively save the patient's life.

Basic host response parameters to classify mortality risk in COVID-19 and community-acquired pneumonia

Improved phenotyping in pneumonia is necessary to strengthen risk assessment. Via a feasible and multidimensional approach with basic parameters, we aimed to evaluate the effect of host response at admission on severity stratification in COVID-19 and community-acquired pneumonia (CAP). Three COVID-19 and one CAP multicenter cohorts including hospitalized patients were recruited. Three easily available variables reflecting different pathophysiologic mechanisms-immune, inflammation, and respiratory-were selected (absolute lymphocyte count [ALC], C-reactive protein [CRP] and, SpO2/FiO2). In-hospital mortality and intensive care unit (ICU) admission were analyzed as outcomes. A multivariable, penalized maximum likelihood logistic regression was performed with ALC (< 724 lymphocytes/mm3), CRP (> 60 mg/L), and, SpO2/FiO2 (< 450). A total of 1452, 1222 and 462 patients were included in the three COVID-19 and 1292 in the CAP cohort for the analysis. Mortality ranged between 4 and 32% (0 to 3 abnormal biomarkers) and 0-9% in SARS-CoV-2 pneumonia and CAP, respectively. In the first COVID-19 cohort, adjusted for age and sex, we observed an increased odds ratio for in-hospital mortality in COVID-19 with elevated biomarkers altered (OR 1.8, 3, and 6.3 with 1, 2, and 3 abnormal biomarkers, respectively). The model had an AUROC of 0.83. Comparable findings were found for ICU admission, with an AUROC of 0.76. These results were confirmed in the other COVID-19 cohorts Similar OR trends were reported in the CAP cohort; however, results were not statistically significant. Assessing the host response via accessible biomarkers is a simple and rapidly applicable approach for pneumonia.

Pulmonary superinfection diagnosed with bronchoalveolar lavage at intubation in COVID patients: A Swedish single-centre study

BACKGROUND

Patients with severe coronavirus disease 2019 (COVID) pneumonia and acute respiratory distress syndrome (C-ARDS) on invasive mechanical ventilation (IMV) have been found to be prone to having other microbial findings than severe acute respiratory syndrome coronavirus 2 (SARS-2)-CoV-19 in the bronchoalveolar lavage (BAL) fluid at intubation causing a superinfection. These BAL results could guide empirical antibiotic treatment in complex clinical situations. However, there are limited data on the relationship between microbial findings in the initial BAL at intubation and later ventilator-associated pneumonia (VAP) diagnoses.

OBJECTIVE

To analyse the incidence of, and microorganisms responsible for, superinfections in C-ARDS patients at the time of first intubation through microbial findings in BAL fluid. To correlate these findings to markers of inflammation in plasma and later VAP development.

DESIGN

Retrospective single-centre study.

SETTING

One COVID-19 intensive care unit (ICU) at a County Hospital in Sweden during the first year of the pandemic.

PATIENTS

All patients with C-ARDS who were intubated in the ICU.

RESULTS

We analysed BAL fluid specimens from 112 patients at intubation, of whom 31 (28%) had superinfections. Blood levels of the C-reactive protein, procalcitonin, neutrophil granulocytes, and lymphocytes were indistinguishable between patients with and without a pulmonary superinfection. Ninety-eight (88%) of the patients were treated with IMV for more than 48 h and of these patients, 37% were diagnosed with VAP. The microorganisms identified in BAL at the time of intubation are normally found at the oral, pharyngeal, and airway sites. Only one patient had an indistinguishable bacterial strain responsible for both superinfection at intubation and in VAP.

CONCLUSIONS

One fourth of the patients with C-ARDS had a pulmonary superinfection in the lungs that was caused by another microorganism identified at intubation. Routine serum inflammatory markers could not be used to identify this complication. Microorganisms located in BAL at intubation were rarely associated with later VAP development.

SFX-01 in hospitalised patients with community-acquired pneumonia during the COVID-19 pandemic: a double-blind, randomised, placebo-controlled trial

Introduction

Sulforaphane can induce the transcription factor, Nrf2, promoting antioxidant and anti-inflammatory responses. In this study, hospitalised patients with community-acquired pneumonia (CAP) were treated with stabilised synthetic sulforaphane (SFX-01) to evaluate impact on clinical status and inflammation.

Methods

Double-blind, randomised, placebo-controlled trial of SFX-01 (300 mg oral capsule, once daily for 14 days) conducted in Dundee, UK, between November 2020 and May 2021. Patients had radiologically confirmed CAP and CURB-65 (confusion, urea >7 mmol·L-1, respiratory rate ≥30 breaths·min-1, blood pressure <90 mmHg (systolic) or ≤60 mmHg (diastolic), age ≥65 years) score ≥1. The primary outcome was the seven-point World Health Organization clinical status scale at day 15. Secondary outcomes included time to clinical improvement, length of stay and mortality. Effects on Nrf2 activity and inflammation were evaluated on days 1, 8 and 15 by measurement of 45 serum cytokines and mRNA sequencing of peripheral blood leukocytes.

Results

The trial was terminated prematurely due to futility with 133 patients enrolled. 65 patients were randomised to SFX-01 treatment and 68 patients to placebo. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was the cause of CAP in 103 (77%) cases. SFX-01 treatment did not improve clinical status at day 15 (adjusted OR 0.87, 95% CI 0.41-1.83; p=0.71), time to clinical improvement (adjusted hazard ratio (aHR) 1.02, 95% CI 0.70-1.49), length of stay (aHR 0.84, 95% CI 0.56-1.26) or 28-day mortality (aHR 1.45, 95% CI 0.67-3.16). The expression of Nrf2 targets and pro-inflammatory genes, including interleukin (IL)-6, IL-1β and tumour necrosis factor-α, was not significantly changed by SFX-01 treatment. At days 8 and 15, respectively, 310 and 42 significant differentially expressed genes were identified between groups (false discovery rate adjusted p<0.05, log2FC >1).

Conclusion

SFX-01 treatment did not improve clinical status or modulate key Nrf2 targets in patients with CAP primarily due to SARS-CoV-2 infection.

Respiratory viral infection and resolution of inflammation: Roles for specialized pro-resolving mediators

Respiratory viral infections with influenza A virus (IAV) or respiratory syncytial virus (RSV) pose a significant threat to public health due to excess morbidity and mortality. Dysregulated and excessive inflammatory responses are major underlying causes of viral pneumonia severity and morbidity, including aberrant host immune responses and increased risk for secondary bacterial infections. Currently available antiviral therapies have not substantially reduced the risk of severe viral pneumonia for these pathogens. Thus, new therapeutic approaches that can promote resolution of the pathogen-initiated inflammation without impairing host defense would represent a significant advance. Recent research has uncovered the potential for specialized pro-resolving mediators (SPMs) to transduce multipronged actions for the resolution of serious respiratory viral infection without increased risk for subsequent host susceptibility to bacterial infection. Here, we review recent advances in our understanding of SPM production and SPM receptor signaling in respiratory virus infections and the intriguing potential of harnessing SPM pathways to control excess morbidity and mortality from IAV and RSV pneumonia.

Identifying clusters of coexisting conditions and outcomes among adults admitted to hospital with community-acquired pneumonia: a multicentre cohort study

BACKGROUND

Little is known about patterns of coexisting conditions and their influence on clinical care or outcomes in adults admitted to hospital for community-acquired pneumonia (CAP). We sought to evaluate how coexisting conditions cluster in this population to advance understanding of how multimorbidity affects CAP.

METHODS

We studied 11 085 adults admitted to hospital with CAP at 7 hospitals in Ontario, Canada. Using cluster analysis, we identified patient subgroups based on clustering of comorbidities in the Charlson Comorbidity Index. We derived and replicated cluster analyses in independent cohorts (derivation sample 2010-2015, replication sample 2015-2017), then combined these into a total cohort for final cluster analyses. We described differences in medications, imaging and outcomes.

RESULTS

Patients clustered into 7 subgroups. The low comorbidity subgroup (n = 3052, 27.5%) had no comorbidities. The DM-HF-Pulm subgroup had prevalent diabetes, heart failure and chronic lung disease (n = 1710, 15.4%). One disease category defined each remaining subgroup, as follows: pulmonary (n = 1621, 14.6%), diabetes (n = 1281, 11.6%), heart failure (n = 1370, 12.4%), dementia (n = 1038, 9.4%) and cancer (n = 1013, 9.1%). Corticosteroid use ranged from 11.5% to 64.9% in the dementia and pulmonary subgroups, respectively. Piperacillin-tazobactam use ranged from 9.1% to 28.0% in the pulmonary and cancer subgroups, respectively. The use of thoracic computed tomography ranged from 5.7% to 36.3% in the dementia and cancer subgroups, respectively. Adjusting for patient factors, the risk of in-hospital death was greater in the cancer (adjusted odds ratio [OR] 3.12, 95% confidence interval [CI] 2.44-3.99), dementia (adjusted OR 1.57, 95% CI 1.05-2.35), heart failure (adjusted OR 1.66, 95% CI 1.35-2.03) and DM-HF-Pulm subgroups (adjusted OR 1.35, 95% CI 1.12-1.61), and lower in the diabetes subgroup (adjusted OR 0.67, 95% CI 0.50-0.89), compared with the low comorbidity group.

INTERPRETATION

Patients admitted to hospital with CAP cluster into clinically recognizable subgroups based on coexisting conditions. Clinical care and outcomes vary among these subgroups with little evidence to guide decision-making, highlighting opportunities for research to personalize care.

An Adjudication Protocol for Severe Pneumonia

Background

Clinical end points that constitute successful treatment in severe pneumonia are difficult to ascertain and vulnerable to bias. The utility of a protocolized adjudication procedure to determine meaningful end points in severe pneumonia has not been well described.

Methods

This was a single-center prospective cohort study of patients with severe pneumonia admitted to the medical intensive care unit. The objective was to develop an adjudication protocol for severe bacterial and/or viral pneumonia. Each episode of pneumonia was independently reviewed by 2 pulmonary and critical care physicians. If a discrepancy occurred between the 2 adjudicators, a third adjudicator reviewed the case. If a discrepancy remained after all 3 adjudications, consensus was achieved through committee review.

Results

Evaluation of 784 pneumonia episodes during 593 hospitalizations achieved only 48.1% interobserver agreement between the first 2 adjudicators and 78.8% when agreement was defined as concordance between 2 of 3 adjudicators. Multiple episodes of pneumonia and presence of bacterial/viral coinfection in the initial pneumonia episode were associated with lower interobserver agreement. For an initial episode of bacterial pneumonia, patients with an adjudicated day 7-8 clinical impression of cure (compared with alternative impressions) were more likely to be discharged alive (odds ratio, 6.3; 95% CI, 3.5-11.6).

Conclusions

A comprehensive adjudication protocol to identify clinical end points in severe pneumonia resulted in only moderate interobserver agreement. An adjudicated end point of clinical cure by day 7-8 was associated with more favorable hospital discharge dispositions, suggesting that clinical cure by day 7-8 may be a valid end point to use in adjudication protocols.

Lung epithelial cell-derived C3 protects against pneumonia-induced lung injury

The complement component C3 is a fundamental plasma protein for host defense, produced largely by the liver. However, recent work has demonstrated the critical importance of tissue-specific C3 expression in cell survival. Here, we analyzed the effects of local versus peripheral sources of C3 expression in a model of acute bacterial pneumonia induced by Pseudomonas aeruginosa. Whereas mice with global C3 deficiency had severe pneumonia-induced lung injury, those deficient only in liver-derived C3 remained protected, comparable to wild-type mice. Human lung transcriptome analysis showed that secretory epithelial cells, such as club cells, express high levels of C3 mRNA. Mice with tamoxifen-induced C3 gene ablation from club cells in the lung had worse pulmonary injury compared with similarly treated controls, despite maintaining normal circulating C3 levels. Last, in both the mouse pneumonia model and cultured primary human airway epithelial cells, we showed that stress-induced death associated with C3 deficiency parallels that seen in Factor B deficiency rather than C3a receptor deficiency. Moreover, C3-mediated reduction in epithelial cell death requires alternative pathway component Factor B. Thus, our findings suggest that a pathway reliant on locally derived C3 and Factor B protects the lung mucosal barrier.

Host response dysregulations amongst adults hospitalized by influenza A H1N1 virus pneumonia: A prospective multicenter cohort study

BACKGROUND

Limited knowledge exists on how early host response impacts outcomes in influenza pneumonia.

METHODS

This study assessed what was the contribution of host immune response at the emergency department on hospital mortality amongst adults with influenza A H1N1pdm09 pneumonia and whether early stratification by immune host response anticipates the risk of death. This is a secondary analysis from a prospective, observational, multicenter cohort comparing 75 adults requiring intensive care with 38 hospitalized in medical wards. Different immune response biomarkers within 24 h of hospitalization and their association with hospital mortality were assessed.

RESULTS

Fifty-three were discharged alive. Non-survivors were associated (p&lt;0.05) with lower lymphocytes (751 vs. 387), monocytes (450 vs. 220) expression of HLA-DR (1,662 vs. 962) and higher IgM levels (178 vs. 152;p&lt;0.01). Lymphocyte subpopulations amongst non-survivors showed a significantly (p&lt;0.05) lower number of TCD3+ (247.2 vs. 520.8), TCD4+ (150.3 vs. 323.6), TCD8+ (95.3 vs. 151.4) and NKCD56+ (21.9 vs. 91.4). Number of lymphocytes, monocytes and NKCD56+ predicted hospital mortality (AUC 0.854). Hospital mortality was independently associated with low HLA-DR values, low number of NKCD56+ cells, and high IgM levels, in a Cox-proportional hazard analysis. A second model, documented that hospital mortality was independently associated with a phenotype combining immunoparalysis with hyperinflammation (HR 5.53; 95%CI 2.16-14.14), after adjusting by predicted mortality.

CONCLUSIONS

We conclude that amongst influenza pneumonia, presence of immunoparalysis was a major mortality driver. Influenza heterogeneity was partly explained by early specific host response dysregulations which should be considered to design personalized approaches of adjunctive therapy.

Machine learning-derived prediction of in-hospital mortality in patients with severe acute respiratory infection: analysis of claims data from the German-wide Helios hospital network

BACKGROUND

Severe acute respiratory infections (SARI) are the most common infectious causes of death. Previous work regarding mortality prediction models for SARI using machine learning (ML) algorithms that can be useful for both individual risk stratification and quality of care assessment is scarce. We aimed to develop reliable models for mortality prediction in SARI patients utilizing ML algorithms and compare its performances with a classic regression analysis approach.

METHODS

Administrative data (dataset randomly split 75%/25% for model training/testing) from years 2016-2019 of 86 German Helios hospitals was retrospectively analyzed. Inpatient SARI cases were defined by ICD-codes J09-J22. Three ML algorithms were evaluated and its performance compared to generalized linear models (GLM) by computing receiver operating characteristic area under the curve (AUC) and area under the precision-recall curve (AUPRC).

RESULTS

The dataset contained 241,988 inpatient SARI cases (75 years or older: 49%; male 56.2%). In-hospital mortality was 11.6%. AUC and AUPRC in the testing dataset were 0.83 and 0.372 for GLM, 0.831 and 0.384 for random forest (RF), 0.834 and 0.382 for single layer neural network (NNET) and 0.834 and 0.389 for extreme gradient boosting (XGBoost). Statistical comparison of ROC AUCs revealed a better performance of NNET and XGBoost as compared to GLM.

CONCLUSION

ML algorithms for predicting in-hospital mortality were trained and tested on a large real-world administrative dataset of SARI patients and showed good discriminatory performances. Broad application of our models in clinical routine practice can contribute to patients' risk assessment and quality management.

Prevalence, nature and trajectory of dysphagia postoesophageal cancer surgery: a prospective longitudinal study protocol

INTRODUCTION

Dysphagia is a common problem following oesophagectomy, and is associated with aspiration pneumonia, malnutrition, weight loss, prolonged enteral feeding tube dependence, in addition to an extended in-hospital stay and compromised quality of life (QOL). To date, the prevalence, nature and trajectory of post-oesophagectomy dysphagia has not been systematically studied in a prospective longitudinal design. The study aims (1) to evaluate the prevalence, nature and trajectory of dysphagia for participants undergoing an oesophagectomy as part of curative treatment, (2) to determine the risk factors for, and post-operative complications of dysphagia in this population and (3) to examine the impact of oropharyngeal dysphagia on health-related QOL across time points.

METHODS AND ANALYSIS

A videofluoroscopy will be completed and analysed on both post-operative day (POD) 4 or 5 and at 6-months post-surgery. Other swallow evaluations will be completed preoperatively, POD 4 or 5, 1-month and 6-month time points will include a swallowing screening test, tongue pressure measurement, cough reflex testing and an oral hygiene evaluation. Nutritional measurements will include the Functional Oral Intake Scale to measure feeding tube reliance, Malnutrition Screening Tool and the Strength, Assistance With Walking, Rise From a Chair, Climb Stairs and Falls questionnaire. The Reflux Symptom Index will be administered to investigate aerodigestive symptoms commonly experienced by adults post-oesophagectomy. Swallowing-related QOL outcome measures will be determined using the European Organisation for Research and Treatment of Cancer QLQ-18, MD Anderson Dysphagia Inventory and the Swallowing Quality of Life Questionnaire.

ETHICS AND DISSEMINATION

Ethical approval has been granted by the Tallaght University Hospital/St. James' Hospital Research Ethics Committee (JREC), Dublin, Ireland (Ref. No. 2021-Jul-310). The study results will be published in peer-reviewed journals and presented at national and international scientific conferences.

Prognostic value of blood urea nitrogen-to-serum albumin ratio for mortality of pneumonia in patients receiving glucocorticoids: Secondary analysis based on a retrospective cohort study

INTRODUCTION

Previous studies have revealed that blood urea nitrogen-to-serum albumin ratio (BUN/ALB) is one of major risk factors of mortality in pneumonia. However, there are fewer scientific research about the correlation between BUN/ALB ratio and outcome of pneumonia in patients receiving glucocorticoids. This study was undertaken to explore the prognostic value of BUN/ALB ratio for mortality of pneumonia in patients receiving glucocorticoids.

METHODS

The present study was a retrospective cohort study. 1397 subjects receiving glucocorticoids alone or glucocorticoids and other immunosuppressants from six secondary and tertiary academic hospitals in China were analyzed. The endpoint of the study was 30-day mortality. It was noted that the entire study was completed by Li et al. and uploaded the data to the DATADRYAD website. The author only used this data for secondary analysis.

RESULTS

After adjusting potential confounders (age, sex, WBC, persistent lymphocytopenia, PLT, ALT, AST, Cr, high-dose steroid use, and COPD), non-linear relationship was detected between BUN/ALB ratio and 30-day mortality, whose point was 0.753. The effect sizes and the confidence intervals on the left and right sides of inflection point were 23.110 (7.157, 74.623) and 0.410 (0.074, 2.283), respectively. Subgroup analysis revealed the positive association was stronger among subjects with connective tissue disease.

CONCLUSIONS

The relationship between BUN/ALB ratio and 30-day mortality of pneumonia in patients receiving glucocorticoids is non-linear. BUN/ALB ratio is positively related with 30-day mortality when BUN/ALB ratio is less than 0.753.

Diagnostic concordance between BioFire® FilmArray® Pneumonia Panel and culture in patients with COVID-19 pneumonia admitted to intensive care units: the experience of the third wave in eight hospitals in Colombia

Background

The detection of coinfections is important to initiate appropriate antimicrobial therapy. Molecular diagnostic testing identifies pathogens at a greater rate than conventional microbiology. We assessed both bacterial coinfections identified via culture or the BioFire® FilmArray® Pneumonia Panel (FA-PNEU) in patients infected with SARS-CoV-2 in the ICU and the concordance between these techniques.

Methods

This was a prospective study of patients with SARS-CoV-2 who were hospitalized for no more than 48 h and on mechanical ventilation for no longer than 24 h in 8 ICUs in Medellín, Colombia. We studied mini-bronchoalveolar lavage or endotracheal aspirate samples processed via conventional culture and the FA-PNEU. Coinfection was defined as the identification of a respiratory pathogen using the FA-PNEU or cultures. Serum samples of leukocytes, C-reactive protein, and procalcitonin were taken on the first day of intubation. We analyzed the empirical antibiotics and the changes in antibiotic management according to the results of the FA-PNEUM and cultures.

Results

Of 110 patients whose samples underwent both methods, FA-PNEU- and culture-positive samples comprised 24.54% versus 17.27%, respectively. Eighteen samples were positive in both techniques, 82 were negative, 1 was culture-positive with a negative FA-PNEU result, and 9 were FA-PNEU-positive with negative culture. The two bacteria most frequently detected by the FA-PNEU were Staphylococcus aureus (37.5%) and Streptococcus agalactiae (20%), and those detected by culture were Staphylococcus aureus (34.78%) and Klebsiella pneumoniae (26.08%). The overall concordance was 90.1%, and when stratified by microorganism, it was between 92.7 and 100%. The positive predictive value (PPV) was between 50 and 100% and were lower for Enterobacter cloacae and Staphylococcus aureus. The negative predictive value (NPV) was high (between 99.1 and 100%); MecA/C/MREJ had a specificity of 94.55% and an NPV of 100%. The inflammatory response tests showed no significant differences between patients whose samples were positive and negative for both techniques. Sixty-one patients (55.45%) received at least one dose of empirical antibiotics.

Conclusions

The overall concordance was 90.1%, and it was between 92.7% and 100% when stratified by microorganisms. The positive predictive value was between 50 and 100%, with a very high NPV.