Procalcitonin as a Marker of Etiology in Adults Hospitalized With Community-Acquired Pneumonia

Increased plasma AACT level as an indicator of poor prognosis in patients hospitalised with community-acquired pneumonia: a multicentre prospective cohort study

BACKGROUND AND OBJECTIVE

Community-acquired pneumonia (CAP) is a common respiratory disease that frequently requires hospitalisation, and is a significant cause of death worldwide. This study aimed to evaluate the usefulness of alpha-1-antichymotrypsin (AACT) as a diagnostic and prognostic biomarker of CAP.

METHODS

We conducted a multicentre prospective cohort study in patients hospitalised with CAP. Plasma AACT levels were measured using a quantitative enzyme-linked immunosorbent assay. Receiver-operating characteristic (ROC) curves and Cox proportional hazards regression were used to assess the association between plasma AACT levels and CAP diagnosis and prognosis.

RESULTS

A total of 274 patients with CAP were enrolled in the study. AACT levels were elevated in patients with CAP, especially those with severe CAP and non-survivors. The area under the curve (AUC) of AACT and CRP for diagnosing CAP was 0.755 and 0.843. Cox regression showed that CURB-65 and AACT levels were independent predictors of 30-day mortality. ROC curves showed that plasma AACT levels had the highest accuracy for predicting acute respiratory distress syndrome (ARDS), with an AUC of 0.862. Combining AACT with Pneumonia Severity Index and CURB-65 significantly improved their predictive accuracy for predicting 30-day mortality.

CONCLUSION

Plasma AACT levels are elevated in patients with CAP, but plasma AACT level is inferior to the C-reactive protein level for diagnosing CAP. The AACT level can reliably predict the occurrence of ARDS and 30-day mortality in patients with CAP.

Evaluating the utility of procalcitonin and a clinical decision support tool to determine duration of antimicrobial therapy for respiratory tract infections

PURPOSE

Procalcitonin (PCT) levels may play a role in decreasing the duration of antimicrobial therapy in institutions that have long durations of therapy for management of community-acquired pneumonia. We assessed the impact of the combination of pharmacist stewardship interventions assisted by a clinical decision support (CDS) tool and PCT assessment on the antimicrobial days of therapy (DOT) prescribed for respiratory tract infections (RTIs).

METHODS

We conducted a quasi-experimental study in which patients in the preintervention group were admitted between April and June 2021 and patients in the intervention group were admitted between April and June 2022. In the intervention phase, a CDS tool was utilized to alert clinical pharmacists when patients met specific criteria. This alert was programmed to activate for individual patients when a reported PCT level was less than 0.25 ng/mL and the patient was on antimicrobials prescribed for an RTI as indicated by providers in the electronic health record. Stewardship interventions were made by pharmacists via prospective audit and feedback. The primary endpoint was inpatient antimicrobial DOT for RTIs.

RESULTS

There were 90 patients in the preintervention group and 104 patients in the intervention group. Although baseline characteristics were not well matched between the groups, favoring the preintervention group, the median DOT was lower in the intervention group, at 3 days (interquartile range [IQR], 2-4 days), compared to 4 days (IQR, 2.8-5 days) in the preintervention group (P = 0.001).

CONCLUSION

The results of our study demonstrate the utility of pharmacist interventions coupled with CDS and PCT in reducing antimicrobial DOT prescribed for RTIs. Antimicrobial stewardship programs may benefit from implementing a PCT bundle.

Predictive signature of murine and human host response to typical and atypical pneumonia

BACKGROUND

Pneumonia due to typical bacterial, atypical bacterial and viral pathogens can be difficult to clinically differentiate. Host response-based diagnostics are emerging as a complementary diagnostic strategy to pathogen detection.

METHODS

We used murine models of typical bacterial, atypical bacterial and viral pneumonia to develop diagnostic signatures and understand the host's response to these types of infections. Mice were intranasally inoculated with Streptococcus pneumoniae, Mycoplasma pneumoniae, influenza or saline as a control. Peripheral blood gene expression analysis was performed at multiple time points. Differentially expressed genes were used to perform gene set enrichment analysis and generate diagnostic signatures. These murine-derived signatures were externally validated in silico using human gene expression data. The response to S. pneumoniae was the most rapid and robust.

RESULTS

Mice infected with M. pneumoniae had a delayed response more similar to influenza-infected animals. Diagnostic signatures for the three types of infection had 0.94-1.00 area under the receiver operator curve (auROC). Validation in five human gene expression datasets revealed auROC of 0.82-0.96.

DISCUSSION

This study identified discrete host responses to typical bacterial, atypical bacterial and viral aetiologies of pneumonia in mice. These signatures validated well in humans, highlighting the conserved nature of the host response to these pathogen classes.

A review of the value of point-of-care testing for community-acquired pneumonia

INTRODUCTION

Community-acquired pneumonia (CAP) is an infectious disease associated with high mortality worldwide. Although Streptococcus pneumoniae remains the most frequent pathogen in CAP, data from recent studies using molecular tests have shown that respiratory viruses play a key role in adults with pneumonia. The impact of difficult-to-treat pathogens on the outcomes of pneumonia is also important even though they represent only a small proportion of overall cases. Despite improvements in the microbiological diagnosis of CAP in recent decades, the identification of the causative pathogen is often delayed because of difficulties in obtaining good-quality sputum samples, issues in transporting samples, and slow laboratory processes. Therefore, the initial treatment of CAP is usually empirical. Point-of-care testing (POCT) was introduced to avoid treatment delays and reduce reliance on empirical antibiotics.

AREAS COVERED

This review summarizes the main scientific evidence on the role of POCT in the diagnosis and management of patients with CAP. The authors searched for articles on POCT in pneumonia on PubMed from inception to 20 January 2024. The references in the identified articles were also searched.

EXPERT OPINION

POCT involves rapid diagnostic assays that can be performed at the bedside especially in cases of severe CAP and immunocompromised patients. These tests can produce results that could help guide initial therapy and management.

Guidelines for Antibiotics Prescription in Critically Ill Patients

How to cite this article: Khilnani GC, Tiwari P, Mittal S, Kulkarni AP, Chaudhry D, Zirpe KG, et al. Guidelines for Antibiotics Prescription in Critically Ill Patients. Indian J Crit Care Med 2024;28(S2):S104-S216.

Effect of Renin-Angiotensin-Aldosterone System Blockers on Adverse Outcomes in COVID-19 Patients

INTRODUCTION

Angiotensin-converting enzyme 2 (ACE2) of the renin-angiotensin-aldosterone system (RAAS) serves as a functional receptor to gain entry into the cells for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19). The interaction between SARS-CoV-2 and ACE2 is a potential virulent factor in infectivity. Our study aimed to ascertain the association of RAAS inhibitors with adverse cardiovascular and other outcomes in hospitalized COVID-19 patients.

METHODS

This is a retrospective study of medical records of ≥18-year-old patients hospitalized for COVID-19 from March 2020 to October 2020. Primary outcomes were acute cardiovascular events (ST-elevation myocardial infarction, non-ST-elevation myocardial infarction type 1, acute congestive heart failure, acute stroke) and mortality. Secondary outcomes were respiratory failure, need for and duration of mechanical ventilation, acute deep vein thrombosis or pulmonary embolism (DVT/PE), and readmission rate.

RESULTS

Among 376 hospitalized COVID-19 patients, 149 were on RAAS inhibitors. No statistically significant differences were found between RAAS inhibitor and non-RAAS inhibitor groups with respect to acute cardiovascular events (6% vs. 6.2%, p = 0.94), acute DVT/PE (4.7% vs. 4.8%, p = 0.97), hypoxia (62.4% vs. 58.6%, p = 0.46), need for mechanical ventilation (18.1% vs. 16.7%, p = 0.72), mortality (19.5% vs. 22%, p = 0.56), and readmission rate (11.4% vs. 14.1%, p = 0.45). Some nuances discovered were a higher rate of hospitalizations among Native Americans receiving RAAS inhibitors (30.2% vs. 19.8%) and significantly lower levels of procalcitonin in patients on RAAS inhibitors.

CONCLUSIONS

Among hospitalized patients with COVID-19, those on RAAS inhibitors showed no significant differences in acute cardiovascular events, acute DVT/PE, hypoxia, need for mechanical ventilation, readmission, or mortality rate compared to those not on them. However, further large-scale studies are needed to validate these findings.

Plasma proteome analysis and validation of patients with community-acquired pneumonia: A cohort study

PURPOSE

This study aimed to investigate the diagnostic potential of plasma biomarkers of community-acquired pneumonia (CAP) and their severity grading.

EXPERIMENTAL DESIGN

Plasma proteomes from cohort I (n = 32) with CAP were analyzed by data-independent acquisition mass spectrometry (MS). MetaboAnalyst 5.0 was used to statistically evaluate significant differences in proteins from different samples, and demographic and clinical data were recorded for all enrolled patients. Cohort II (n = 80) was used to validate candidate biomarkers. Plasma protein levels were determined using quantitative enzyme-linked immunosorbent assay (ELISA). Correlations were assessed using Pearson's correlation coefficient. A receiver operating characteristic curve was used to verify the association between the variables, CAP diagnosis, and prognosis.

RESULTS

121 differentially expressed proteins (DEPs) were obtained between CAP and controls. These DEPs were mainly aggregated in pathways of phagosome(hsa04145) and complement and coagulation cascades (hsa04610). No significant differential proteins were detected in bacterial, viral, and mixed infection groups. The plasma levels of fetuin-A, alpha-1-antichymotrypsin (AACT), α1-acid glycoprotein (A1AG), and S100A8/S100A9 heterodimers detected by ELISA were consistent with those of MS. AACT, A1AG, S100A8/S100A9 heterodimer, and fetuin-A can potentially be used as diagnostic predictors, and fetuin-A and AACT are potential predictors of SCAP.

CONCLUSIONS AND CLINICAL RELEVANCE

Plasma protein profiling can successfully identify potential biomarkers for CAP diagnosis and disease severity assessment. These biomarkers should be further studied for their clinical application.

Value of a secretomic approach for distinguishing patients with COVID-19 viral pneumonia among patients with respiratory distress admitted to intensive care unit

In intensive care units, COVID-19 viral pneumonia patients (VPP) present symptoms similar to those of other patients with Nonviral infection (NV-ICU). To better manage VPP, it is therefore interesting to better understand the molecular pathophysiology of viral pneumonia and to search for biomarkers that may clarify the diagnosis. The secretome being a set of proteins secreted by cells in response to stimuli represents an opportunity to discover new biomarkers. The objective of this study is to identify the secretomic signatures of VPP with those of NV-ICU. Plasma samples and clinical data from NV-ICU (n = 104), VPP (n = 30) or healthy donors (HD, n = 20) were collected at Nantes Hospital (France) upon admission. Samples were enriched for the low-abundant proteins and analyzed using nontarget mass spectrometry. Specifically deregulated proteins (DEP) in VPP versus NV-ICU were selected. Combinations of 2 to 4 DEPs were established. The differences in secretome profiles of the VPP and NV-ICU groups were highlighted. Forty-one DEPs were specifically identified in VPP compared to NV-ICU. We describe five of the best combinations of 3 proteins (complement component C9, Ficolin-3, Galectin-3-binding protein, Fibrinogen alpha, gamma and beta chain, Proteoglycan 4, Coagulation factor IX and Cdc42 effector protein 4) that show a characteristic receptor function curve with an area under the curve of 95.0%. This study identifies five combinations of candidate biomarkers in VPP compared to NV-ICU that may help distinguish the underlying causal molecular alterations.

Serum procalcitonin as a diagnostic biomarker in dogs with bacterial respiratory diseases

BACKGROUND

Procalcitonin (PCT) is a useful biomarker in humans in the identification of bacterial respiratory infections.

OBJECTIVES

The aim of this study was to investigate the utility of serum PCT measurements as a diagnostic biomarker in canine bacterial lower respiratory tract diseases.

METHODS

PCT concentrations were measured in serum samples with an ELISA method previously validated for dogs. All dogs underwent thorough clinical examinations, and the diagnosis of respiratory disease was based on clinical and laboratory findings, diagnostic imaging, as well as cytology and bacterial culture of respiratory samples. PCT concentrations between different cohorts of dogs were compared with an ANOVA-model.

RESULTS

Sixty-two privately owned dogs with respiratory diseases, 25 with bacterial pneumonia (BP), 17 with bacterial bronchitis caused by Bordetella bronchiseptica (BB), and 20 with chronic bronchitis (CB) as well as 44 healthy controls were included in the study. Serum PCT concentrations in dogs with bacterial respiratory diseases (BP mean 51.8 ng/L ± standard deviation [SD] 40.6 ng/L and BB mean 61.4 ng/L ± SD 35.3 ng/L) were not significantly different when compared with dogs with a non-bacterial respiratory disease (CB mean 89.7 ± SD 73.5 ng/L) or healthy dogs (mean 51.0 ng/L ± SD 37.5 ng/L, p > .05 in all comparisons).

CONCLUSIONS

These results indicate that despite being a valuable diagnostic, prognostic, and follow-up marker in humans with pneumonia, serum PCT concentrations are not elevated in dogs with bacterial respiratory diseases and, therefore, cannot be used as a diagnostic biomarker in dogs.

Clinical Predictors of Bacteremia Outcome After Initial Empirical Antimicrobial Therapy in Patients with Hematological Malignancies: A Retrospective Analysis

Objective

We performed a retrospective analysis to investigate the clinical predictors of bacteremia outcome involving Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) after initial empirical antimicrobial therapy among hematological malignancy cases.

Methods

This retrospective study was conducted between April 2018 and April 2023. All bloodstream infections (BSIs) caused by E. coli and K. pneumoniae in hospitalized hematological malignancy (HM) patients were identified. Data on patient demographics, clinical characteristics, empirical antimicrobial treatment, outcomes and the antimicrobial susceptibility were collected from medical records. Multivariate analyses were utilized to assess the risk factors for all-cause mortality within 28 days and carbapenem resistance. Optimal cutoffs for continuous predictive variables were evaluated by receiver operating characteristic (ROC) curve analysis.

Results

Among 61 individuals diagnosed with bacteremia, 39 cases were caused by E. coli bacteremia, while the remaining 22 were identified as K. pneumoniae bacteremia. Out of these, there were 10 cases of carbapenem-resistant Enterobacteriaceae (CRE) and 12 cases resulted in all-cause mortality within 28 days. Analysis indicated that Pitt score was an independent risk factor for mortality and a cut-off of 2.5 was a reliable predictor with 83.3% sensitivity and 85.7% specificity, respectively. Impaired mental status and elevated body temperature exceeding 38.6°C as well as a procalcitonin (PCT) level over 8.24 ng/mL on the third day (d3) after antimicrobial treatment were identified as independent risk factors for predicting carbapenem resistance.

Conclusion

We found that Pitt score with a cut-off of 2.5 was a reliable predictor for mortality within 28 days in HM bacteremia cases. Impaired mental status and elevated temperature exceeding 38.6°C as well as a procalcitonin (PCT) level over 8.24 ng/mL on d3 after antimicrobial treatment were identified as predictive risk factors to carbapenem resistance.

Diagnostic testing and antibiotic utilization among inpatients evaluated for coronavirus disease 2019 (COVID-19) pneumonia

We evaluated diagnostic test and antibiotic utilization among 252 patients from 11 US hospitals who were evaluated for coronavirus disease 2019 (COVID-19) pneumonia during the severe acute respiratory coronavirus virus 2 (SARS-CoV-2) omicron variant pandemic wave. In our cohort, antibiotic use remained high (62%) among SARS-CoV-2-positive patients and even higher among those who underwent procalcitonin testing (68%).

Optimizing Antimicrobial Stewardship in the Emergency Department

Antibiotic stewardship is a core component of emergency department (ED) practice and impacts patient safety, clinical outcomes, and public health. The unique characteristics of ED practice, including crowding, time pressure, and diagnostic uncertainty, need to be considered when implementing antibiotic stewardship interventions in this setting. Rapid advances in pathogen detection and host response biomarkers promise to revolutionize the diagnosis of infectious diseases in the ED, but such tests are not yet considered standard of care. Presently, clinical decision support embedded in the electronic health record and pharmacist-led interventions are the most effective ways to improve antibiotic prescribing in the ED.

Improved diagnostic markers for invasive pulmonary aspergillosis in COPD patients

Background

The prevalence of invasive pulmonary aspergillosis (IPA) among patients with chronic obstructive pulmonary disease (COPD) is steadily increasing, leading to high mortality. Although early diagnosis can significantly reduce mortality, the efficacy of current diagnostic methods is limited. Consequently, there is a need for novel approaches for early IPA detection.

Methods

This retrospective study involved 383 hospitalized COPD patients with GOLD stages III and IV. The IPA group (67 patients) and non-IPA group (316 patients) were identified at the First Affiliated Hospital of Guangzhou Medical University between January 2016 and February 2022. We analyzed common serological indicators in our hospital to identify predictive indicators for the early diagnosis of IPA in COPD patients.

Results

The sensitivity and specificity of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), procalcitonin (PCT), lactate dehydrogenase (LDH), and ceruloplasmin (CER) for diagnosing IPA in COPD patients were as follows: CRP (91.2%, 57.7%), ESR (77.5%, 73.0%), PCT (60.5%, 71.4%), LDH (50.0%, 88.8%), and CER (60.7%, 74.3%). Combinations of biomarkers, such as CRP-ESR, CRP-LDH, ESR-LDH, ESR-CER, and LDH-CER, showed promising diagnostic potential, with larger area under the curve (AUC) values for IPA diagnosis in COPD patients. However, no statistically significant difference was observed between the diagnostic efficacy of single biomarkers and combined biomarkers. Notably, compared to those in the unassisted ventilation group, the patients in the assisted ventilation group (including noninvasive ventilation and tracheal intubation/incision-assisted ventilation group) exhibited significantly greater PCT and LDH levels, while the CER significantly decreased (p=0.021). There were no significant differences in biomarker levels between the ICU group and the non-ICU group. CRP (p<0.01), ESR (p=0.028), PCT (p<0.01), and CER (p<0.01) were positively correlated with hospitalization duration, whereas LDH was not correlated with hospitalization duration.

Conclusion

Our study highlights the diagnostic potential of CRP, ESR, PCT, LDH, and CER for IPA in COPD patients. CRP and LDH can also initially predict the need for assisted ventilation, while CRP can initially estimate the length of hospitalization. This study represents the first report of the potential of CER for diagnosing IPA, suggesting its significance for further research.

Biomarkers: Are They Useful in Severe Community-Acquired Pneumonia?

Community acquired pneumonia (CAP) is a prevalent infectious disease often requiring hospitalization, although its diagnosis remains challenging as there is no gold standard test. In severe CAP, clinical and radiologic criteria have poor sensitivity and specificity, and microbiologic documentation is usually delayed and obtained in less than half of sCAP patients. Biomarkers could be an alternative for diagnosis, treatment monitoring and establish resolution. Beyond the existing evidence about biomarkers as an adjunct diagnostic tool, most evidence comes from studies including CAP patients in primary care or emergency departments, and not only sCAP patients. Ideally, biomarkers used in combination with signs, symptoms, and radiological findings can improve clinical judgment to confirm or rule out CAP diagnosis, and may be valuable adjunctive tools for risk stratification, differentiate viral pneumonia and monitoring the course of CAP. While no single biomarker has emerged as an ideal one, CRP and PCT have gathered the most evidence. Overall, biomarkers offer valuable information and can enhance clinical decision-making in the management of CAP, but further research and validation are needed to establish their optimal use and clinical utility.

PLUS-IS-LESS project: Procalcitonin and Lung UltraSonography-based antibiotherapy in patients with Lower rESpiratory tract infection in Swiss Emergency Departments: study protocol for a pragmatic stepped-wedge cluster-randomized trial

BACKGROUND

Lower respiratory tract infections (LRTIs) are among the most frequent infections and a significant contributor to inappropriate antibiotic prescription. Currently, no single diagnostic tool can reliably identify bacterial pneumonia. We thus evaluate a multimodal approach based on a clinical score, lung ultrasound (LUS), and the inflammatory biomarker, procalcitonin (PCT) to guide prescription of antibiotics. LUS outperforms chest X-ray in the identification of pneumonia, while PCT is known to be elevated in bacterial and/or severe infections. We propose a trial to test their synergistic potential in reducing antibiotic prescription while preserving patient safety in emergency departments (ED).

METHODS

The PLUS-IS-LESS study is a pragmatic, stepped-wedge cluster-randomized, clinical trial conducted in 10 Swiss EDs. It assesses the PLUS algorithm, which combines a clinical prediction score, LUS, PCT, and a clinical severity score to guide antibiotics among adults with LRTIs, compared with usual care. The co-primary endpoints are the proportion of patients prescribed antibiotics and the proportion of patients with clinical failure by day 28. Secondary endpoints include measurement of change in quality of life, length of hospital stay, antibiotic-related side effects, barriers and facilitators to the implementation of the algorithm, cost-effectiveness of the intervention, and identification of patterns of pneumonia in LUS using machine learning.

DISCUSSION

The PLUS algorithm aims to optimize prescription of antibiotics through improved diagnostic performance and maximization of physician adherence, while ensuring safety. It is based on previously validated tests and does therefore not expose participants to unforeseeable risks. Cluster randomization prevents cross-contamination between study groups, as physicians are not exposed to the intervention during or before the control period. The stepped-wedge implementation of the intervention allows effect calculation from both between- and within-cluster comparisons, which enhances statistical power and allows smaller sample size than a parallel cluster design. Moreover, it enables the training of all centers for the intervention, simplifying implementation if the results prove successful. The PLUS algorithm has the potential to improve the identification of LRTIs that would benefit from antibiotics. When scaled, the expected reduction in the proportion of antibiotics prescribed has the potential to not only decrease side effects and costs but also mitigate antibiotic resistance.

TRIAL REGISTRATION

This study was registered on July 19, 2022, on the ClinicalTrials.gov registry using reference number: NCT05463406.

TRIAL STATUS

Recruitment started on December 5, 2022, and will be completed on November 3, 2024. Current protocol version is version 3.0, dated April 3, 2023.

The utility of procalcitonin for identifying secondary infections in patients with influenza or COVID-19 receiving extracorporeal membrane oxygenation

Background

Identifying secondary infections in patients receiving extracorporeal membrane oxygenation (ECMO) presents challenges due to the ECMO circuit's influence on traditional signs of infection.

Objectives

This study evaluates procalcitonin as a diagnostic marker for secondary infections in patients receiving ECMO with influenza or COVID-19 infection.

Design

Single-center retrospective cohort study.

Methods

All adult patients receiving veno-venous ECMO with underlying influenza or COVID-19 from November 2017 to October 2021 were included. Patient demographics, time receiving ECMO, culture data, and procalcitonin levels were examined. The first procalcitonin within 3 days of infection was compared to negative workups that were collected at least 10 days from the last positive culture. Furthermore, we compared procalcitonin levels by the type of pathogen and site of infection.

Results

In this study, 84 patients with influenza or COVID-19 who received ECMO were included. A total of 276 procalcitonin labs were ordered in this cohort, with 33/92 (36%) of the secondary infections having an associated procalcitonin value. When comparing procalcitonin levels, there was no significant difference between the infection and negative workup groups [1 ng/mL (interquartile ranges, IQR: 0.4-1.2) versus 1.3 (0.5-4.3), p = 0.19]. Using 0.5 ng/mL as the cut-off, the sensitivity of procalcitonin was 67% and the specificity was 30%. In our cohort, the positive predictive value of procalcitonin was 14.5% and the negative predictive value was 84%. There was no difference in procalcitonin by type of organism or site of infection. Procalcitonin levels did not routinely decline even after an infection was identified.

Conclusion

While procalcitonin is a proposed potential diagnostic marker for secondary infections in patients receiving ECMO, this single-center study demonstrated low sensitivity and specificity of procalcitonin in identifying secondary infections. Furthermore, there was no association of procalcitonin levels with etiology of infection when one was present. Procalcitonin should be used cautiously in identifying infections in veno-venous ECMO.

A high α1-antitrypsin/interleukin-10 ratio predicts bacterial pneumonia in adults with community-acquired pneumonia: a prospective cohort study

BACKGROUND

Current microbiological tests fail to identify the causative microorganism in more than half of all pneumonia cases. We explored biomarkers that could be used for differentiating between bacterial and viral pneumonia in patients with community-acquired pneumonia (CAP).

METHODS

In this prospective cohort study conducted in Japan, data obtained from adult patients with bacterial pneumonia, including bacterial and viral coinfections (bacterial pneumonia [BP] group), and purely viral pneumonia (VP group) at diagnosis were analyzed using multivariate logistic regression analysis to identify predictors of bacterial pneumonia. Furthermore, a decision tree was developed using the predictors.

RESULTS

A total of 210 patients were analyzed. The BP and VP groups comprised 108 and 18 patients, respectively. The other 84 patients had no identified causative microorganism. The two groups shared similar characteristics, including disease severity; however, a significant difference (p < 0.05) was observed between the two groups regarding sputum type; sputum volume score; neutrophil counts; and serum levels of interleukin (IL)-8, IL-10, and α1-antitrypsin (AAT). Sputum volume score (p < 0.001), IL-10 (p < 0.001), and AAT (p = 0.008) were ultimately identified as predictors of BP. The area under the curve for these three variables on the receiver operating characteristic (ROC) curve was 0.927 (95% confidence interval [CI]: 0.881-0.974). The ROC curve for sputum volume score and an AAT/IL-10 ratio showed a diagnostic cutoff of 1 + and 65, respectively. Logistic regression analysis using dichotomized variables at the cutoff values showed that the odds ratios for the diagnosis of BP were 10.4 (95% CI: 2.2-50.2) for sputum volume score (absence vs. presence) and 19.8 (95% CI: 4.7-83.2) for AAT/IL-10 ratio (< 65 vs. ≥ 65).

CONCLUSIONS

Considering that obtaining a definitive etiologic diagnosis with the current testing methods is difficult and time consuming, a decision tree with two predictors, namely sputum volume and the AAT/IL-10 ratio, can be useful in predicting BP among patients diagnosed with CAP and facilitating the appropriate use of antibiotics.

TRIAL REGISTRATION

UMIN000034673 registered on November 29, 2018.

Management of pneumonia in the critically ill

Pneumonias continue to be major public health issues and are commonly encountered in the intensive care setting. The most common types of pneumonia leading to critical illness include severe community acquired pneumonia, hospital acquired pneumonia, and ventilator associated pneumonia. Early evaluation, diagnosis, and escalation to appropriate levels of care are imperative to improving survival. Treatment remains challenging with the need to balance antibiotic stewardship and minimizing patient harm. As evidenced in the most recent society guidelines, the identification of risk factors for severe disease and the causative pathogens are crucial in guiding the most appropriate therapy.

Misleading Procalcitonin in Patients With Staphylococcus aureus Bacteremia: A Report of Two Cases

Procalcitonin (PCT) is an important biomarker for bacterial infection with a high negative predictive value. It is almost always positive in patients who are bacteremic with pathogenic bacteria. Here, we report two cases of Staphylococcus aureus bacteremia, where PCT levels were unexpectedly negative. This uncommon occurrence challenges the assumption of PCT's infallibility as a diagnostic marker in patients with true bacteremia. The first case is a 55-year-old woman with no past medical issues who presented with one week of generalized weakness and two days of fever and chills. Though her white blood cell (WBC) count and c-reactive protein (CRP) were elevated, PCT was normal, with no apparent source of infection, and hence antibiotic differed. However, her blood cultures returned positive for methicillin-resistant Staphylococcus aureus (MRSA). The patient was started on vancomycin and discharged on daptomycin, she responded appropriately and improved. The second case is an intravenous (IV) drug user, a 40-year-old woman, who presented with septic arthritis and osteomyelitis involving the right hip. She had blood cultures positive for methicillin-susceptible Staphylococcus aureus (MSSA); however, a PCT check on the day of positive blood cultures and various occasions subsequently was normal. These two cases remind us that we cannot over-rely on one test to rule out bacterial infection and should consider the whole clinical picture. They highlight the need for vigilance among clinicians that PCT can rarely be negative in cases of true bacteremia in spite of its high negative predictive value. Physicians and antibiotic stewardship programs should be cautious and aware of this potential pitfall when utilizing PCT as a diagnostic tool.

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.

One biomarker does not fit all: tailoring anti-infective therapy through utilization of procalcitonin and other specific biomarkers

INTRODUCTION

Considering the ongoing increase in antibiotic resistance, the importance of judicious use of antibiotics through reduction of exposure is crucial. Adding procalcitonin (PCT) and other biomarkers to pathogen-specific tests may help to further improve antibiotic therapy algorithms and advance antibiotic stewardship programs to achieve these goals.

AREAS COVERED

In recent years, several trials have investigated the inclusion of biomarkers such as PCT into clinical decision-making algorithms. For adult patients, findings demonstrated improvements in the individualization of antibiotic treatment, particularly for patients with respiratory tract infections and sepsis. While most trials were performed in hospitals with central laboratories, point-of-care testing might further advance the field by providing a cost-effective and rapid diagnostic tool in upcoming years. Furthermore, novel biomarkers including CD-64, presepsin, Pancreatic stone and sTREM-1, have all shown promising results for increased accuracy of sepsis diagnosis. Availability of these markers however is currently still limited and there is insufficient evidence for their routine use in clinical care.

EXPERT OPINION

In addition to new host-response markers, combining such biomarkers with pathogen-directed diagnostics present a promising strategy to increase algorithm accuracy in differentiating between bacterial and viral infections. Recent advances in microbiologic testing using PCR or nucleic amplification tests may further improve the diagnostic yield and promote more targeted pathogen-specific antibiotic therapy.

The potential clinical value of pairing procalcitonin and lung ultrasonography to guide antibiotic therapy in patients with community-acquired pneumonia: a narrative review

INTRODUCTION

Lower respiratory tract infections (LRTIs) are among the most frequent infections and are prone to inappropriate antibiotic treatments. This results from a limited accuracy of diagnostic tools in identifying bacterial pneumonia. Lung ultrasound (LUS) has excellent sensitivity and specificity in diagnosing pneumonia. Additionally, elevated procalcitonin (PCT) levels correlate with an increased likelihood of bacterial infection. LUS and PCT appear to be complementary in identifying patients with bacterial pneumonia who are likely to benefit from antibiotics.

AREAS COVERED

This narrative review aims to summarize the current evidence for LUS to diagnose pneumonia, for PCT to guide antibiotic therapy and the clinical value of pairing both tools.

EXPERT OPINION

LUS has excellent diagnostic accuracy for pneumonia in different settings, regardless of the examiner's experience. PCT guidance safely reduces antibiotic prescription in LRTIs. The combination of both tools has demonstrated an enhanced accuracy in the diagnosis of pneumonia, including CAP in the ED and VAP in the ICU, but randomized controlled studies need to validate the clinical impact of a combined approach.

Procalcitonin as a biomarker to guide treatments for patients with lower respiratory tract infections

INTRODUCTION

Lower respiratory tract infections are amongst the main causes for hospital/intensive care unit admissions and antimicrobial prescriptions. In order to reduce antimicrobial pressure, antibiotic administration could be optimized through procalcitonin-based algorithms.

AREAS COVERED

In this review, we discuss the performances of procalcitonin for the diagnosis and the management of community-acquired and ventilator-associated pneumonia. We provide up-to-date evidence and deliver clear messages regarding the purpose of procalcitonin to reduce unnecessary antimicrobial exposure.

EXPERT OPINION

Antimicrobial pressure and resulting antimicrobial resistances are a major public health issue as well as a daily struggle in the management of patients with severe infectious diseases, especially in intensive care units where antibiotic exposure is high. Procalcitonin-guided antibiotic administration has proven its efficacy in reducing unnecessary antibiotic use in lower respiratory tract infections without excess in mortality, hospital length of stay or disease relapse. Procalcitonin-guided algorithms should be implemented in wards taking care of patients with severe infections. However, procalcitonin performances are different regarding the setting of the infection (community versus hospital-acquired infections) the antibiotic management (start or termination of antibiotic) as well as patient's condition (immunosuppressed or in shock) and we encourage the physicians to be aware of these limitations.

Usefulness of serum procalcitonin and point-of-care multiplex PCR gastro-intestinal panel in acute diarrhea or colitis in the emergency department

Introduction: Acute infectious diarrhea is one of the most common diseases worldwide. Procalcitonin (PCT) is useful for antibiotic stewardship in lower respiratory tract infections but has been poorly studied in infectious diarrhea. Our objective is to describe the PCT concentrations according to diarrhea etiology.Methods: This is a single-center prospective cohort study involving adults consulting the emergency department (ED) for an acute diarrhea or colitis. Serum PCT was measured and a stool sample was tested with FilmArray® Gastro-Intestinal Panel. The primary endpoint is the PCT concentration according to each type of pathogen identified using Gastro-Intestinal-panel and/or stool cultures at ED admission.Results: 125 patients were included: 80 had an acute infectious diarrhea, 21 an acute colitis and 24 another illness causing diarrhea. The median (interquartile ranges) PCT values (ng/ml) were 0.13 (0.08-0.28), 0.07 (0.06-0.54), 0.13 (0.09-0.26) and 0.05 (0.03-0.17), respectively if there was a bacteria (n = 41), parasite (n = 3), virus (n = 10) or no pathogen identified and 0.34 (0.13-1.03) if the diarrhea was due to another illness (n = 24).Conclusion: In patients admitted to the ED with an acute infectious diarrhea or acute colitis, PCT remained low when a bacteria was identified. It may not be informative in current practice to guide antibiotic therapy.

Hematological Parameters and Procalcitonin as Discriminants between Bacterial Pneumonia-Induced Sepsis and Viral Sepsis Secondary to COVID-19: A Retrospective Single-Center Analysis

Bacterial and viral sepsis induce alterations of all hematological parameters and procalcitonin is used as a biomarker of infection and disease severity. Our aim was to study the hematological patterns associated with pulmonary sepsis triggered by bacteria and Severe Acute Respiratory Syndrome-Coronavirus-type-2 (SARS-CoV-2) and to identify the discriminants between them. We performed a retrospective, observational study including 124 patients with bacterial sepsis and 138 patients with viral sepsis. Discriminative ability of hematological parameters and procalcitonin between sepsis types was tested using receiver operating characteristic (ROC) analysis. Sensitivity (Sn%), specificity (Sp%), positive and negative likelihood ratios were calculated for the identified cut-off values. Patients with bacterial sepsis were older than patients with viral sepsis (p < 0.001), with no differences regarding gender. Subsequently to ROC analysis, procalcitonin had excellent discriminative ability for bacterial sepsis diagnosis with an area under the curve (AUC) of 0.92 (cut-off value of >1.49 ng/mL; Sn = 76.6%, Sp = 94.2%), followed by RDW% with an AUC = 0.87 (cut-off value >14.8%; Sn = 80.7%, Sp = 85.5%). Leukocytes, monocytes and neutrophils had good discriminative ability with AUCs between 0.76-0.78 (p < 0.001), while other hematological parameters had fair or no discriminative ability. Lastly, procalcitonin value was strongly correlated with disease severity in both types of sepsis (p < 0.001). Procalcitonin and RDW% had the best discriminative ability between bacterial and viral sepsis, followed by leukocytes, monocytes and neutrophils. Procalcitonin is a marker of disease severity regardless of sepsis type.

Splenic Abscess: A Rare Complication of Bacterial Pneumonia

Splenic abscess is a rare condition with potentially life-threatening evolution. Hematogenous spread is the most common cause of splenic abscess. Contiguous spread after bacterial pneumonia has rarely been reported in the literature. Early diagnosis can be made by a combination of imaging modalities and clinical features. The successful management of splenic abscess includes timely medical therapy, computed tomography (CT)-guided percutaneous aspiration, and splenectomy. In this report, we discuss a rare case of splenic abscess after hospitalization for bacterial pneumonia. The aim of this case report is to raise awareness about this rare complication so that prompt and appropriate management can be quickly performed to prevent severe outcomes.

Overruling of Procalcitonin-Guided Antibiotics for Lower Respiratory Tract Infections in Primary Care: Ancillary Study of a Randomized Controlled Trial

BACKGROUND

Lower respiratory tract infections (LRTIs) in primary care are a promising target for antibiotic stewardship. A clinical trial in Switzerland showed a large decrease in antibiotic prescriptions with procalcitonin guidance (cut-off < 0.25 µg/L) compared with usual care. However, one-third of patients with low procalcitonin at baseline received antibiotics by day 28.

AIM

To explore the factors associated with the overruling of initial procalcitonin guidance.

DESIGN AND SETTING

Secondary analysis of a cluster randomized trial in which patients with an LRTI were included.

METHOD

Using the characteristics of patients, their disease, and general practitioners (GPs), we conducted a multivariate logistic regression, adjusted for clustering.

RESULTS

Ninety-five out of 301 (32%) patients with low procalcitonin received antibiotics by day 28. Factors associated with an overruling of procalcitonin guidance were: a history of chest pain (adjusted OR [aOR] 1.81, 95% confidence interval 1.03-3.17); a prescription of chest X-ray by the GP (aOR 4.65, 2.32-9.34); a C-reactive protein measured retrospectively above 100 mg/L (aOR 7.48, 2.34-23.93, reference ≤ 20 mg/L); the location of the GP practice in an urban setting (aOR 2.27, 1.18-4.37); and the GP's number of years of experience (aOR per year 1.05, 1.01-1.09).

CONCLUSIONS

Overruling of procalcitonin guidance was associated with GPs' socio-demographic characteristics, pointing to the general behavioral problem of overprescription by physicians. Continuous medical education and communication training might support the successful implementation of procalcitonin point-of-care tests aimed at antibiotic stewardship.

Antimicrobial Stewardship Techniques for Critically Ill Patients with Pneumonia

Pneumonia is common in the intensive care unit (ICU), infecting 27% of all critically ill patients. Given the high prevalence of this disease state in the ICU, optimizing antimicrobial therapy while minimizing toxicities is of utmost importance. Inappropriate antimicrobial use can increase the risk of antimicrobial resistance, Clostridiodes difficile infection, allergic reaction, and other complications from antimicrobial use (e.g., QTc prolongation, thrombocytopenia). This review article aims to discuss methods to optimize antimicrobial treatment in patients with pneumonia, including the following: procalcitonin use, utilization of methicillin-resistant Staphylococcus aureus nares testing to determine need for vancomycin therapy, utilization of the Biofire^® FilmArray^® pneumonia polymerase chain reaction (PCR), and microbiology reporting techniques.

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.

Prognostic value of procalcitonin in cancer patients with coronavirus disease 2019

OBJECTIVES

Many biomarkers have been studied to assist in the risk stratification and prognostication of patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Procalcitonin (PCT), a circulating precursor of the hormone calcitonin, has been studied with mixed results as a predictor of severe coronavirus disease 2019 (COVID-19) in the general population; however, to date, no studies have focused on the utility of PCT in predicting disease severity and death from COVID-19 in the cancer population.

METHODS

We conducted a retrospective study of cancer patients hospitalized with COVID-19 at a comprehensive cancer center over a 10-month period who had PCT recorded on admission. We assessed associations between variables of clinical interest and the primary outcomes of progression of COVID-19 and death during or within 30 days of hospitalization using univariable and multivariable logistic regression.

RESULTS

The study included 209 unique patients. In the univariate analysis, elevated PCT on admission was associated with higher odds of progression of COVID-19 or death (Odds ratio [OR] 1.40, 95% CI 1.08-1.93) and mortality alone (OR 1.53, 95% CI 1.17-2.11). In multivariate regression, PCT remained significantly associated with progression or death after holding chronic kidney disease (CKD) status constant (OR 1.40, 95% CI: 1.08, 1.93, p=0.003). Similarly, the association of PCT and death remained significant after adjusting for age (OR 1.54, 95% CI: 1.17-2.15).

CONCLUSIONS

In hospitalized COVID-19 patients with underlying cancer, initial PCT levels on admission may be associated with prognosis, involving higher odds of progression of COVID-19 and/or mortality.

The Role of Biomarkers in Influenza and COVID-19 Community-Acquired Pneumonia in Adults

Pneumonia is a growing problem worldwide and remains an important cause of morbidity, hospitalizations, intensive care unit admission and mortality. Viruses are the causative agents in almost a fourth of cases of community-acquired pneumonia (CAP) in adults, with an important representation of influenza virus and SARS-CoV-2 pneumonia. Moreover, mixed viral and bacterial pneumonia is common and a risk factor for severity of disease. It is critical for clinicians the early identification of the pathogen causing infection to avoid inappropriate antibiotics, as well as to predict clinical outcomes. It has been extensively reported that biomarkers could be useful for these purposes. This review describe current evidence and provide recommendations about the use of biomarkers in influenza and SARS-CoV-2 pneumonia, focusing mainly on procalcitonin (PCT) and C-reactive protein (CRP). Evidence was based on a qualitative analysis of the available scientific literature (meta-analyses, randomized controlled trials, observational studies and clinical guidelines). Both PCT and CRP levels provide valuable information about the prognosis of influenza and SARS-CoV-2 pneumonia. Additionally, PCT levels, considered along with other clinical, radiological and laboratory data, are useful for early diagnosis of mixed viral and bacterial CAP, allowing the proper management of the disease and adequate antibiotics prescription. The authors propose a practical PCT algorithm for clinical decision-making to guide antibiotic initiation in cases of influenza and SARS-CoV-2 pneumonia. Further well-design studies are needed to validate PCT algorithm among these patients and to confirm whether other biomarkers are indeed useful as diagnostic or prognostic tools in viral pneumonia.

Trends in the Use of Procalcitonin at US Children's Hospital Emergency Departments

OBJECTIVES

Procalcitonin (PCT) was approved by the Food and Drug Administration in 2016. We assessed changes in PCT utilization over time in emergency departments (EDs) at US Children's Hospitals and identified the most common conditions associated with PCT testing.

METHODS

We performed a cross-sectional study of children <18 years of age presenting to 1 of 33 EDs contributing data to the Pediatric Health Information System between 2016 and 2020. We examined trends in PCT utilization during an ED encounter between institutions and over the study period. Using All Patients Refined Diagnosis Related Groups, we identified the most common conditions for which PCT was obtained (overall, and relative to the performance of a complete blood count).

RESULTS

The overall rate of PCT testing increased from 0.2% of all ED visits in 2016 to 1.8% in 2020. Across hospitals, the proportion of ED encounters with PCT obtained ranged from 0.0005% to 4.3% with marked variability in overall use. Among children who had PCT testing performed, the most common diagnoses were fever (10.7%), infections of the upper respiratory tract (9.2%), and pneumonia (5.9%). Relative to the performance of a complete blood count, rates of PCT testing were highest among children with sepsis (28.7%), fever (21.4%), pulmonary edema/respiratory failure (17.3%), and bronchiolitis/respiratory syncytial virus pneumonia (15.6%).

CONCLUSIONS

PCT utilization in the ED has increased over the past 5 years with variation between hospitals. PCT is most frequently obtained for children with respiratory infections and febrile illnesses.

Serum Ferritin as a Predictor of Outcomes in Hospitalized Patients with Covid-19 Pneumonia

Purpose: Elevated ferritin levels are associated with poor outcomes in Covid-19 patients. Optimal timing of ferritin assessment and the merit of longitudinal values remains unclear. Methods: Patients admitted to Henry Ford Hospital with confirmed SARS-CoV-2 were studied. Regression models were used to determine the relation between ferritin and mortality, need for mechanical ventilation, ICU admission, and days on the ventilator. Results: 2265 patients were evaluated. Patients with an initial ferritin of > 490 ng/mL had an increased risk of death (OR 3.4, P < .001), admission to the ICU (OR 2.78, P < .001) and need for mechanical ventilation (OR 3.9, P < .001). There was no difference between admission and Day 1 ICU ferritin levels (611.5 ng/mL vs. 649 ng/mL respectively; P = .07). The decline in ferritin over ICU days 1-4 was similar between survivors and non-survivors. A change in ferritin levels from admission to ICU Day 1 (P = .330), or from ICU Day 1 to 2 (P = .788), did not predict days on the ventilator. Conclusions: Initial Ferritin levels were highly predictive of ICU admission, the need for mechanical ventilation and in-hospital mortality. However, longitudinal measures of ferritin throughout the hospital stay did not provide additional predictive value.

Benchmarking transcriptional host response signatures for infection diagnosis

Identification of host transcriptional response signatures has emerged as a new paradigm for infection diagnosis. For clinical applications, signatures must robustly detect the pathogen of interest without cross-reacting with unintended conditions. To evaluate the performance of infectious disease signatures, we developed a framework that includes a compendium of 17,105 transcriptional profiles capturing infectious and non-infectious conditions and a standardized methodology to assess robustness and cross-reactivity. Applied to 30 published signatures of infection, the analysis showed that signatures were generally robust in detecting viral and bacterial infections in independent data. Asymptomatic and chronic infections were also detectable, albeit with decreased performance. However, many signatures were cross-reactive with unintended infections and aging. In general, we found robustness and cross-reactivity to be conflicting objectives, and we identified signature properties associated with this trade-off. The data compendium and evaluation framework developed here provide a foundation for the development of signatures for clinical application. A record of this paper's transparent peer review process is included in the supplemental information.

When Influenza, Bacterial Pneumonia, and COVID-19 Co-exist

In the United States, influenza virus and bacterial pneumonia are known to be the leading causes of hospitalization in the winter season. Although healthcare workers are knowledgeable about the management of these co-infections, with the coronavirus disease 2019 (COVID-19) global pandemic that occurred in 2019, a significant change has occurred. The symptoms and clinical manifestations of COVID-19 are similar to that of influenza virus and bacterial pneumonia which can present a unique challenge for healthcare workers. Many reports are available for influenza virus and bacterial pneumonia but none about influenza, bacterial pneumonia, and COVID-19 co-infection. Here, we present the case of a patient who was admitted with COVID-19, influenza, and bacterial pneumonia co-infection, along with his clinical characteristics, laboratory findings, treatment plan, and outcomes.

Prevention and treatment of ventilator-associated pneumonia in COVID-19

Ventilator-associated pneumonia (VAP) is the most common acquired infection in the intensive care unit. Recent studies showed that the critical COVID-19 patients with invasive mechanical ventilation have a high risk of developing VAP, which result in a worse outcome and an increasing economic burden. With the development of critical care medicine, the morbidity and mortality of VAP remains high. Especially since the outbreak of COVID-19, the healthcare system is facing unprecedented challenges. Therefore, many efforts have been made in effective prevention, early diagnosis, and early treatment of VAP. This review focuses on the treatment and prevention drugs of VAP in COVID-19 patients. In general, prevention is more important than treatment for VAP. Prevention of VAP is based on minimizing exposure to mechanical ventilation and encouraging early release. There is little difference in drug prophylaxis from non-COVID-19. In term of treatment of VAP, empirical antibiotics is the main treatment, special attention should be paid to the antimicrobial spectrum and duration of antibiotics because of the existence of drug-resistant bacteria. Further studies with well-designed and large sample size were needed to demonstrate the prevention and treatment of ventilator-associated pneumonia in COVID-19 based on the specificity of COVID-19.

Diagnostic Accuracy of a Bacterial and Viral Biomarker Point-of-Care Test in the Outpatient Setting

Importance

Acute respiratory infections (ARIs) account for most outpatient visits. Discriminating bacterial vs viral etiology is a diagnostic challenge with therapeutic implications.

Objective

To investigate whether FebriDx, a rapid, point-of-care immunoassay, can differentiate bacterial- from viral-associated host immune response in ARI through measurement of myxovirus resistance protein A (MxA) and C-reactive protein (CRP) from finger-stick blood.

Design, Setting, and Participants

This diagnostic study enrolled adults and children who were symptomatic for ARI and individuals in a control group who were asymptomatic between October 2019 and April 2021. Included participants were a convenience sample of patients in outpatient settings (ie, emergency department, urgent care, and primary care) who were symptomatic, aged 1 year or older, and had suspected ARI and fever within 72 hours. Individuals with immunocompromised state and recent vaccine, antibiotics, stroke, surgery, major burn, or myocardial infarction were excluded. Of 1685 individuals assessed for eligibility, 259 individuals declined participation, 718 individuals were excluded, and 708 individuals were enrolled (520 patients with ARI, 170 patients without ARI, and 18 individuals who dropped out).

Exposures

Bacterial and viral immunoassay testing was performed using finger-stick blood. Results were read at 10 minutes, and treating clinicians and adjudicators were blinded to results.

Main Outcomes and Measures

Bacterial- or viral-associated systemic host response to an ARI as determined by a predefined comparator algorithm with adjudication classified infection etiology.

Results

Among 520 participants with ARI (230 male patients [44.2%] and 290 female patients [55.8%]; mean [SD] age, 35.3 [17.7] years), 24 participants with missing laboratory information were classified as unknown (4.6%). Among 496 participants with a final diagnosis, 73 individuals (14.7%) were classified as having a bacterial-associated response, 296 individuals (59.7%) as having a viral-associated response, and 127 individuals (25.6%) as negative by the reference standard. The bacterial and viral test correctly classified 68 of 73 bacterial infections, demonstrating a sensitivity of 93.2% (95% CI, 84.9%-97.0%), specificity of 374 of 423 participants (88.4% [95% CI, 85.0%-91.1%]), positive predictive value (PPV) of 68 of 117 participants (58.1% [95% CI, 49.1%-66.7%), and negative predictive value (NPV) of 374 of 379 participants (98.7% [95% CI, 96.9%-99.4%]).The test correctly classified 208 of 296 viral infections, for a sensitivity of 70.3% (95% CI, 64.8%-75.2%), a specificity of 176 of 200 participants (88.0% [95% CI, 82.8%-91.8%]), a PPV of 208 of 232 participants (89.7% [95% CI, 85.1%-92.9%]), and an NPV of 176 of 264 participants (66.7% [95% CI, 60.8%-72.1%]).

Conclusions and Relevance

In this study, a rapid diagnostic test demonstrated diagnostic performance that may inform clinicians when assessing for bacterial or viral etiology of ARI symptoms.

Inverse relationship between IL-6 and sodium levels in patients with COVID-19 and other respiratory tract infections: data from the COVIVA study

Objective

Hyponatremia in COVID-19 is often due to the syndrome of inadequate antidiuresis (SIAD), possibly mediated by interleukin-6 (IL-6)-induced non-osmotic arginine vasopressin (AVP) secretion. We hypothesized an inverse association between IL-6 and plasma sodium concentration, stronger in COVID-19 compared to other respiratory infections.

Design

Secondary analysis of a prospective cohort study including patients with COVID-19 suspicion admitted to the Emergency Department, University Hospital of Basel, Switzerland, between March and July 2020.

Methods

We included patients with PCR-confirmed COVID-19 and patients with similar symptoms, further subclassified into bacterial and other viral respiratory infections. The primary objective was to investigate the association between plasma sodium and IL-6 levels.

Results

A total of 500 patients were included, 184 (37%) with COVID-19, 92 (18%) with bacterial respiratory infections, and 224 (45%) with other viral respiratory infections. In all groups, median (IQR) IL-6 levels were significantly higher in hyponatremic compared to normonatremic patients (COVID-19: 43.4 (28.4, 59.8) vs 9.2 (2.8, 32.7) pg/mL, P < 0.001; bacterial: 122.1 (63.0, 282.0) vs 67.1 (24.9, 252.0) pg/mL, P < 0.05; viral: 14.1 (6.9, 84.7) vs 4.3 (2.1, 14.4) pg/mL, P < 0.05). IL-6 levels were negatively correlated with plasma sodium levels in COVID-19, whereas the correlation in bacterial and other viral infections was weaker (COVID-19: R = -0.48, P < 0.001; bacterial: R = -0.25, P = 0.05, viral: R = -0.27, P < 0.001).

Conclusions

IL-6 levels were inversely correlated with plasma sodium levels, with a stronger correlation in COVID-19 compared to bacterial and other viral infections. IL-6 might stimulate AVP secretion and lead to higher rates of hyponatremia due to the SIAD in these patients.

Guidelines for the Use of Procalcitonin for Rational Use of Antibiotics

How to cite this article: Khilnani GC, Tiwari P, Zirpe KG, Chaudhary D, Govil D, Dixit S, et al. Guidelines for the Use of Procalcitonin for Rational Use of Antibiotics. Indian J Crit Care Med 2022;26(S2):S77-S94.

Frontline workers: Mediators of mucosal immunity in community acquired pneumonia and COVID-19

The current COVID-19 pandemic has highlighted a need to further understand lung mucosal immunity to reduce the burden of community acquired pneumonia, including that caused by the SARS-CoV-2 virus. Local mucosal immunity provides the first line of defence against respiratory pathogens, however very little is known about the mechanisms involved, with a majority of literature on respiratory infections based on the examination of peripheral blood. The mortality for severe community acquired pneumonia has been rising annually, even prior to the current pandemic, highlighting a significant need to increase knowledge, understanding and research in this field. In this review we profile key mediators of lung mucosal immunity, the dysfunction that occurs in the diseased lung microenvironment including the imbalance of inflammatory mediators and dysbiosis of the local microbiome. A greater understanding of lung tissue-based immunity may lead to improved diagnostic and prognostic procedures and novel treatment strategies aimed at reducing the disease burden of community acquired pneumonia, avoiding the systemic manifestations of infection and excess morbidity and mortality.

Diagnostic Accuracy of Procalcitonin upon Emergency Department Admission during SARS-CoV-2 Pandemic

INTRODUCTION

Procalcitonin is a marker for bacterial diseases and has been used to guide antibiotic prescription. Procalcitonin accuracy, measured at admission, in patients with community-acquired pneumonia (CAP), is unknown in the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic.

OBJECTIVES

To evaluate the diagnostic accuracy of procalcitonin to assess the need for antibiotic treatment in patients with CAP presenting to the emergency department during the SARS-CoV-2 pandemic.

METHODS

We performed a real-world diagnostic retrospective accuracy study of procalcitonin in patients admitted to the emergency department. Measures of diagnostic accuracy were calculated based on procalcitonin results compared to the reference standard of combined microbiological and radiological analysis. Sensitivity, specificity, positive and negative predictive values, and area under (AUC) the receiver-operating characteristic (ROC) curve were calculated in two analyses: first assessing procalcitonin ability to differentiate microbiologically proven bacteria from viral CAP and then clinically diagnosed bacterial CAP from viral CAP.

RESULTS

When using a procalcitonin threshold of 0.5 ng/mL to identify bacterial etiology within patients with CAP, we observed sensitivity and specificity of 50% and 64.1%, and 43% and 82.6%, respectively, in the two analyses. The positive and negative predictive values of a procalcitonin threshold of 0.5 ng/mL to identify patients for whom antibiotics should be advised were 46.4% and 79.7%, and 48.9% and 79% in the two analyses, respectively. The AUC for the two analyses was 0.60 (95% confidence interval [CI] 0.52-0.68) and 0.62 (95% CI, 0.55-0.69).

CONCLUSIONS

Procalcitonin measured upon admission during the SARS-CoV-2 pandemic should not guide antibiotic treatment in patients with CAP.

ARDS Clinical Practice Guideline 2021

BACKGROUND

The joint committee of the Japanese Society of Intensive Care Medicine/Japanese Respiratory Society/Japanese Society of Respiratory Care Medicine on ARDS Clinical Practice Guideline has created and released the ARDS Clinical Practice Guideline 2021.

METHODS

The 2016 edition of the Clinical Practice Guideline covered clinical questions (CQs) that targeted only adults, but the present guideline includes 15 CQs for children in addition to 46 CQs for adults. As with the previous edition, we used a systematic review method with the Grading of Recommendations Assessment Development and Evaluation (GRADE) system as well as a degree of recommendation determination method. We also conducted systematic reviews that used meta-analyses of diagnostic accuracy and network meta-analyses as a new method.

RESULTS

Recommendations for adult patients with ARDS are described: we suggest against using serum C-reactive protein and procalcitonin levels to identify bacterial pneumonia as the underlying disease (GRADE 2D); we recommend limiting tidal volume to 4-8 mL/kg for mechanical ventilation (GRADE 1D); we recommend against managements targeting an excessively low SpO2 (PaO2) (GRADE 2D); we suggest against using transpulmonary pressure as a routine basis in positive end-expiratory pressure settings (GRADE 2B); we suggest implementing extracorporeal membrane oxygenation for those with severe ARDS (GRADE 2B); we suggest against using high-dose steroids (GRADE 2C); and we recommend using low-dose steroids (GRADE 1B). The recommendations for pediatric patients with ARDS are as follows: we suggest against using non-invasive respiratory support (non-invasive positive pressure ventilation/high-flow nasal cannula oxygen therapy) (GRADE 2D), we suggest placing pediatric patients with moderate ARDS in the prone position (GRADE 2D), we suggest against routinely implementing NO inhalation therapy (GRADE 2C), and we suggest against implementing daily sedation interruption for pediatric patients with respiratory failure (GRADE 2D).

CONCLUSIONS

This article is a translated summary of the full version of the ARDS Clinical Practice Guideline 2021 published in Japanese (URL: https://www.jsicm.org/publication/guideline.html ). The original text, which was written for Japanese healthcare professionals, may include different perspectives from healthcare professionals of other countries.

Negative predictive value of procalcitonin to rule out bacterial respiratory co-infection in critical covid-19 patients

Background

: Procalcitonin (PCT) and C-Reactive Protein (CRP) are useful biomarkers to differentiate bacterial from viral or fungal infections, although the association between them and co-infection or mortality in COVID-19 remains unclear.

Methods

: The study represents a retrospective cohort study of patients admitted for COVID-19 pneumonia to 84 ICUs from ten countries between (March 2020-January 2021). Primary outcome was to determine whether PCT or CRP at admission could predict community-acquired bacterial respiratory co-infection (BC) and its added clinical value by determining the best discriminating cut-off values. Secondary outcome was to investigate its association with mortality. To evaluate the main outcome, a binary logistic regression was performed. The area under the curve evaluated diagnostic performance for BC prediction.

Results

: 4635 patients were included, 7.6% fulfilled BC diagnosis. PCT (0.25[IQR 0.1-0.7] versus 0.20[IQR 0.1-0.5]ng/mL, p<0.001) and CRP (14.8[IQR 8.2-23.8] versus 13.3 [7-21.7]mg/dL, p=0.01) were higher in BC group. Neither PCT nor CRP were independently associated with BC and both had a poor ability to predict BC (AUC for PCT 0.56, for CRP 0.54). Baseline values of PCT<0.3ng/mL, could be helpful to rule out BC (negative predictive value 91.1%) and PCT≥0.50ng/mL was associated with ICU mortality (OR 1.5,p<0.001).

Conclusions

: These biomarkers at ICU admission led to a poor ability to predict BC among patients with COVID-19 pneumonia. Baseline values of PCT<0.3ng/mL may be useful to rule out BC, providing clinicians a valuable tool to guide antibiotic stewardship and allowing the unjustified overuse of antibiotics observed during the pandemic, additionally PCT≥0.50ng/mL might predict worsening outcomes.

Stemming the Rise of Antibiotic Use for Community-Acquired Acute Respiratory Infections during COVID-19 Pandemic

At the start of the COVID-19 pandemic, there was an increase in the use of antibiotics for the treatment of community-acquired respiratory tract infection (CA-ARI) in patients admitted for suspected or confirmed COVID-19, raising concerns for misuse. These antibiotics are not under the usual purview of the antimicrobial stewardship unit (ASU). Serum procalcitonin, a biomarker to distinguish viral from bacterial infections, can be used to guide antibiotic recommendations in suspected lower respiratory tract infection. We modified our stewardship approach, and used a procalcitonin-guided strategy to identify “high yield” interventions for audits in patients admitted with CA-ARI. With this approach, there was an increase in the proportion of patients with antibiotics discontinued within 4 days (16.5% vs. 34.9%, p < 0.001), and the overall duration of antibiotic therapy was significantly shorter [7 (6−8) vs. 6 (3−8) days, p < 0.001]. There was a significant decrease in patients with intravenous-to-oral switch of antibiotics to “complete the course” (45.3% vs. 34.4%, p < 0.05). Of the patients who had antibiotics discontinued, none were restarted on antibiotics within 48 h, and there was no-30-day readmission or 30-day mortality attributed to respiratory infection. This study illustrates the importance of the antimicrobial stewardship during the pandemic and the need for ASU to remain attuned to prescriber’s practices, and adapt accordingly to address antibiotic misuse to curb antimicrobial resistance.

ARDS clinical practice guideline 2021

BACKGROUND

The joint committee of the Japanese Society of Intensive Care Medicine/Japanese Respiratory Society/Japanese Society of Respiratory Care Medicine on ARDS Clinical Practice Guideline has created and released the ARDS Clinical Practice Guideline 2021.

METHODS

The 2016 edition of the Clinical Practice Guideline covered clinical questions (CQs) that targeted only adults, but the present guideline includes 15 CQs for children in addition to 46 CQs for adults. As with the previous edition, we used a systematic review method with the Grading of Recommendations Assessment Development and Evaluation (GRADE) system as well as a degree of recommendation determination method. We also conducted systematic reviews that used meta-analyses of diagnostic accuracy and network meta-analyses as a new method.

RESULTS

Recommendations for adult patients with ARDS are described: we suggest against using serum C-reactive protein and procalcitonin levels to identify bacterial pneumonia as the underlying disease (GRADE 2D); we recommend limiting tidal volume to 4-8 mL/kg for mechanical ventilation (GRADE 1D); we recommend against managements targeting an excessively low SpO₂ (PaO₂) (GRADE 2D); we suggest against using transpulmonary pressure as a routine basis in positive end-expiratory pressure settings (GRADE 2B); we suggest implementing extracorporeal membrane oxygenation for those with severe ARDS (GRADE 2B); we suggest against using high-dose steroids (GRADE 2C); and we recommend using low-dose steroids (GRADE 1B). The recommendations for pediatric patients with ARDS are as follows: we suggest against using non-invasive respiratory support (non-invasive positive pressure ventilation/high-flow nasal cannula oxygen therapy) (GRADE 2D); we suggest placing pediatric patients with moderate ARDS in the prone position (GRADE 2D); we suggest against routinely implementing NO inhalation therapy (GRADE 2C); and we suggest against implementing daily sedation interruption for pediatric patients with respiratory failure (GRADE 2D).

CONCLUSIONS

This article is a translated summary of the full version of the ARDS Clinical Practice Guideline 2021 published in Japanese (URL: https://www.jrs.or.jp/publication/jrs_guidelines/). The original text, which was written for Japanese healthcare professionals, may include different perspectives from healthcare professionals of other countries.

Evaluation of Procalcitonin's Utility to Predict Concomitant Bacterial Pneumonia in Critically Ill COVID-19 Patients

Background: Historically, procalcitonin(PCT) has been used as a predictor of bacterial infection and to guide antibiotic therapy in hospitalized patients. The purpose of this study was to determine PCT's diagnostic utility in predicting secondary bacterial pneumonia in critically ill patients with severe COVID-19 pneumonia. Methods: A retrospective cohort study was conducted in COVID-19 adults admitted to the ICU between March 2020, and March 2021. All included patients had a PCT level within 72 h of presentation and serum creatinine of <1.5mg/dL. A PCT threshold of 0.5ng/mL was used to compare patients with high( ≥ 0.5ng/mL) versus low(< 0.5ng/mL) PCT. Bacterial pneumonia was defined by positive respiratory culture. A receiver operating characteristics (ROC) curve was utilized to evaluate PCT as a diagnostic test for bacterial pneumonia, with an area under the curve(AUC) threshold of 0.7 to signify an accurate diagnostic test. A multivariable model was constructed to identify variables associated with in-hospital mortality. Results: There were 165 patients included: 127 low PCT versus 38 high PCT. There was no significant difference in baseline characteristics, vital signs, severity of disease, or outcomes among low versus high PCT groups (all p > 0.05). While there was no difference in bacterial pneumonia in low versus high groups (34(26.8%) versus 12(31.6%), p = 0.562), more patients in the high PCT group had bacteremia (19(15%) versus 11(28.9%), p = 0.050). Sensitivity was 26.1% and specificity was 78.2% for PCT to predict bacterial pneumonia coinfection in ICU patients with COVID-19 pneumonia. ROC yielded an AUC 0.54 (p = 0.415). After adjusting for LDH>350U/L and creatinine in multivariable regression, PCT did not enhance performance of the regression model. Conclusions: PCT offers little to no predictive utility in diagnosing concomitant bacterial pneumonia in critically ill patients with COVID-19 nor in predicting increased severity of disease or worse outcomes including mortality.

Prevalence of Discordant Procalcitonin Use at an Academic Medical Center

OBJECTIVES

Despite multiple trials demonstrating that procalcitonin (PCT) is an effective tool for antibiotic stewardship, inconsistent application in real-world settings continues to fuel controversy regarding its clinical utility. We sought to determine rates of concordance between PCT results and antibiotic prescribing in hospitalized patients.

METHODS

We performed a retrospective review of all inpatient encounters at an academic tertiary care health system with a PCT result between February 2017 and October 2019. Concordant prescribing was defined as starting or continuing antibiotics following an elevated PCT (>0.5 ng/mL) finding and withholding or stopping antibiotics following a low PCT (< 0.1 ng/mL) finding.

RESULTS

Antibiotic prescribing decisions were discordant from the PCT level in 32.5% of our sample. Among patients not receiving antibiotics at the time of testing, 25.9% (430 of 1,662) were prescribed antibiotics despite a low PCT result. Among patients already receiving antibiotics, treatment was continued despite a low PCT level in 80.4% (728 of 906) of cases. Enhanced decision support tools introduced during the study period had no impact on PCT use for antibiotic decisions.

CONCLUSIONS

Overall concordance between PCT results and antibiotic use is relatively low in a real-world setting. The potential value of PCT for antibiotic stewardship may not be fully realized.

Host Transcriptional Signatures Predict Etiology in Community-Acquired Pneumonia: Potential Antibiotic Stewardship Tools

Background:

Current approaches for pathogen identification in community-acquired pneumonia (CAP) remain suboptimal, leaving most patients without a microbiological diagnosis. If better diagnostic tools were available for differentiating between viral and bacterial CAP, unnecessary antibacterial therapy could be avoided in viral CAP patients.

Methods:

In 156 adults hospitalized with CAP classified to have bacterial, viral, or mixed viral-bacterial infection based on microbiological testing or both microbiological testing and procalcitonin (PCT) levels, we aimed to identify discriminatory host transcriptional signatures in peripheral blood samples acquired at hospital admission, by applying Dual-color-Reverse-Transcriptase-Multiplex-Ligation-dependent-Probe-Amplification (dc-RT MLPA).

Results:

In patients classified by microbiological testing, a 9-transcript signature showed high accuracy for discriminating bacterial from viral CAP (AUC 0.91, 95% CI 0.85-0.96), while a 10-transcript signature similarly discriminated mixed viral-bacterial from viral CAP (AUC 0.91, 95% CI 0.86-0.96). In patients classified by both microbiological testing and PCT levels, a 13-transcript signature showed excellent accuracy for discriminating bacterial from viral CAP (AUC 1.00, 95% CI 1.00-1.00), while a 7-transcript signature similarly discriminated mixed viral-bacterial from viral CAP (AUC 0.93, 95% CI 0.87-0.98).

Conclusion:

Our findings support host transcriptional signatures in peripheral blood samples as a potential tool for guiding clinical decision-making and antibiotic stewardship in CAP.

Systematic review of clinical practice guidelines on the management of community acquired pneumonia in children

Childhood community acquired pneumonia (CAP) is the leading cause of mortality in children under 5 years worldwide. Clinical practice guidelines (CPGs) may be limited by method of development, scope of recommendations and the quality of supporting evidence. This study systematically identified, appraised and compared the recommendations of CPGs for the management of paediatric CAP using the AGREE II tool. The systematic review yielded 1409 non-duplicate results, of which 14 CPGs were appraised. Four of the fourteen CPGs were deemed high quality. Most CPGs were considered low-medium quality with 'rigour of development' and 'applicability' the weakest domains. These areas should be considered in deriving CPGs in the future. Recommendations were generally similar across all guidelines; however, there was notable heterogeneity in three areas. This suggests the need for further evidence to guide management decisions on oxygen saturation thresholds for admission, the utility of investigations such as acute phase reactants, and the duration of antibiotic therapy.