In vitro and in vivo calcitonin I gene expression in parenchymal cells: a novel product of human adipose tissue

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.

Prognosis prediction of procalcitonin within 24 h for acute diquat poisoning

BACKGROUND

To explore the predictive value of procalcitonin (PCT) within 24 h after poisoning for prognosis of acute diquat poisoning.

METHODS

This retrospective study included acute diquat poisoning patients in the Nanyang City Hospital between May 2017 and July 2021.

RESULTS

Among the 45 patients included, 27 survived. The maximum PCT value within 24 h after poisoning was significantly higher in the non-survival patients [9.65 (2.63, 22.77) vs. 0.15 (0.10, 0.50) µg/mL, P < 0.001] compared to the survival patients. The area under the ROC curve (AUC) indicated that the maximum PCT value within 24 h had a good predictive value (AUC = 0.905, 95% CI: 0.808-1.000) compared to ingested quantity (AUC = 0.879, 95% CI: 0.776-0.981), serum creatinine (AUC = 0.776, 95% CI: 0.640-0.912), or APACHE II score (AUC = 0.778, 95% CI: 0.631-0.925). The predictive value of maximum PCT value within 24 h was comparable with blood lactate (AUC = 0.904, 95%CI: 0.807-1.000).

CONCLUSIONS

The maximum PCT value within 24 h after poisoning might be a good predictor for the prognosis of patients with acute diquat poisoning.

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.

Advances in sepsis biomarkers

Sepsis, a dysregulated host immune response to an infectious agent, significantly increases morbidity and mortality for hospitalized patients worldwide. This chapter reviews (1) the basic principles of infectious diseases, pathophysiology and current definition of sepsis, (2) established sepsis biomarkers such lactate, procalcitonin and C-reactive protein, (3) novel, newly regulatory-cleared/approved biomarkers, such as assays that evaluate white blood cell properties and immune response molecules, and (4) emerging biomarkers and biomarker panels to highlight future directions and opportunities in the diagnosis and management of sepsis.

Diagnostic utility of procalcitonin for bacterial infections in diabetic ketoacidosis

Procalcitonin is a widely used infection biomarker; however, its utility in identifying bacterial infection in diabetic ketoacidosis (DKA) is unclear. We aimed to evaluate its diagnostic performance for detecting DKA cases triggered by bacterial infections. We reviewed 303 case records of patients aged ≥ 13 years with DKA admitted to the emergency department, PGIMER (Chandigarh), between 2017 and 2022. Baseline procalcitonin was measured by electrochemiluminescence immunoassay, and a value > 0.5 ng/mL was considered elevated. Both microbiological reference standard (MRS) and composite reference standard (CRS) were used to evaluate the diagnostic performance of procalcitonin. 151/303 (49.8%) DKA cases had infection precipitations. Bacterial infections were present in 98 patients (53 microbiologically confirmed), of which urinary tract infection (n = 42), pneumonia (n = 19), skin and soft-tissue infection (n = 13), and bacteremia (n = 11) were common. The median value of procalcitonin was higher with bacterial infections than in patients without (3.68 vs. 1.00, P-value < 0.001). An elevated procalcitonin to detect bacterial infections in DKA had sensitivity 84.69%, specificity 34.15%, positive likelihood ratio (LR +) 1.29, and negative likelihood ratio (LR -) 2.44, against CRS. Against MRS, both LR + and LR - further decreased to 1.23 and 1.81, respectively. Using the receiver-operating-characteristic curve, an optimal cut-off of procalcitonin was calculated at 1.775 ng/ml against both CRS (area under curve 0.655, sensitivity 68.37%, specificity 59.02%, LR + 1.67, LR - 1.86, Yoden's index 0.274) and MRS (area under curve 0.616, sensitivity 67.92%, specificity 59.02%, LR + 1.66, LR - 1.84, Yoden's index 0.269). Procalcitonin does not help detect bacterial infections in patients with DKA at admission.

Diagnosis of septic shock by serum measurement of human neutrophil lipocalin by a rapid homogeneous assay

BACKGROUND

Human neutrophil lipocalin (HNL) is a marker of neutrophil activation and has a high efficacy in diagnosing bacterial infections. In this study, we applied the AlphaLISA technique to measure the serum level of HNL, evaluate HNL's efficacy in diagnosing septic shock, and identify any association between HNL level and septic patients' prognosis.

METHODS

We collected 146 serum samples from the Fifth Medical Center of Chinese PLA General Hospital. HNL was measured by AlphaLISA and results were compared with commercial ELISA kits. We studied 78 patients admitted to the ICU with sepsis and data on their clinical and physiological characteristics were recorded. Blood levels of HNL, procalcitonin (PCT), high-sensitivity C-reactive protein (hs-CRP), and lactate were measured. A receiver operating characteristic (ROC) curve was used to evaluate the performance of each marker.

RESULTS

The AlphaLISA assay for serum HNL had a detection range from 1.5 ng/mL to 1000 ng/mL, with a detection limit of 1 ng/mL and a detection time of approximately 25 min. The AlphaLISA assay's results were in high agreement with ELISA results (R2 = 0.9413). HNL levels were analyzed in sepsis patients, and HNL was significantly higher in sepsis patients with shock compared to sepsis patients without shock (median 356.47 ng/mL vs 158.93 ng/mL, P < 0.0001) and in the 28-day non-survivor group compared to the 28-day survivor group (median 331.83 ng/mL vs 175.17 ng/mL, P < 0.0001). ROC curve analysis was performed for the biomarkers. In differentiating the diagnosis of septic shock from sepsis patients, HNL was the most effective marker (AUC = 0.857), followed by PCT (AUC = 0.754) and hs-CRP (AUC = 0.627). In predicting the prognosis of septic patients, lactate had the best effect (AUC = 0.805), followed by HNL (AUC = 0.784), PCT (AUC = 0.721), and hs-CRP (AUC = 0.583).

CONCLUSIONS

As an assessment tool, we found that our AlphaLISA had good consistency with an ELISA and had several other advantages, including requiring a shorter processing time and detecting a wider range of serum HNL concentrations. Monitoring serum HNL levels of patients admitted to the ICU might be useful in distinguishing sepsis patients who have septic shock from other sepsis patients, indicating its value in the prediction of sepsis patient prognosis.

Relationship between the diagnosis of food protein-induced enterocolitis syndrome and postemetic procalcitonin levels

Background

There are no reports on the relationship between food protein-induced enterocolitis syndrome (FPIES) diagnosis and procalcitonin levels.

Objective

Our study sought to demonstrate a correlation between the presence or absence and severity of FPIES symptoms and postemetic procalcitonin levels.

Methods

The subjects were 53 patients with FPIES (44 with hen's egg allergy, 4 with milk allergy, 4 with wheat allergy, and 3 with soy allergy), who collectively underwent a total of 75 oral food challenges (OFCs). Procalcitonin levels at 5 hours after antigen ingestion were compared between patients with a positive OFC result and those with a negative OFC result and between patients who experienced mild or moderate events and those who experienced severe events.

Results

At 5 hours after ingestion of the causative food, the median procalcitonin levels in patients with a negative OFC result, patients who experienced a mild or moderate event, and patients who experienced a severe event were 0.02, 0.03, and 0.16 ng/mL, respectively. The procalcitonin level was significantly higher in the groups with a positive OFC result than in the groups with a negative OFC result (P < .001), and it was significantly higher in those who experienced severe events than in those who experienced mild or moderate events (P = .012).

Conclusion

Measurement of procalcitonin levels has the potential to provide a quantitative and objective assessment of FPIES diagnosis and severity.

Inflammatory response after out-of-hospital cardiac arrest-Impact on outcome and organ failure development

BACKGROUND

Post-cardiac arrest syndrome that occurs in out-of-hospital cardiac arrest (OHCA) patients is characterized by inflammatory response. We conducted a scoping review of current evidence regarding several inflammatory markers' usefulness for assessment of patient outcome and illness severity. We also discuss the proposed underlying mechanisms leading to inflammatory response after OHCA.

METHODS

We searched the MEDLINE, PubMed Central, Cochrane CENTRAL and Web of Science Core Collection databases with the following search terms: ("inflammation" OR "cytokines") AND "out-of-hospital cardiac arrest." Each inflammatory marker found was combined with "out-of-hospital cardiac arrest" using "AND" to find further relevant studies. We included original studies measuring inflammatory markers in adult OHCA patients that assessed their prognostic capabilities for mortality, neurological outcome, or organ failure severity.

RESULTS

Fifty-nine studies met the inclusion criteria, covering in total 65 different markers. Interleukin-6 (IL-6), procalcitonin (PCT) and C-reactive protein (CRP) were the most studied markers, and they were associated with poor outcomes in 13/15, 13/14 and 11/17 studies, respectively. Based on area under the receiver operating characteristic curve (AUC) value, the time point of best discriminatory capacity for poor outcome was ICU admission for IL-6 (median AUC 0.78, range 0.71-0.98) and day one after OHCA for PCT (median AUC 0.84, range 0.61-0.98). Seven studies reported AUCs for CRP (range 0.52-0.76) with no measurement time point being superior to others. The association of IL-6 and PCT with outcome appeared stronger in studies with more severely ill patients. Studies reported conflicting results regarding each marker's association with organ failure severity.

CONCLUSION

Inflammatory markers are potentially useful for early risk stratification after OHCA. PCT and IL-6 have moderate prognostic value during the first 24 h of the ICU stay. Predictive accuracy appears to be associated with the study overall event rate.

Reduced Reliability of Procalcitonin (PCT) as a Biomarker of Bacterial Superinfection: Concerns about PCT-Driven Antibiotic Stewardship in Critically Ill COVID-19 Patients-Results from a Retrospective Observational Study in Intensive Care Units

BACKGROUND

The aim of this study was to assess whether procalcitonin levels is a diagnostic tool capable of accurately identifying sepsis and ventilator-associated pneumonia (VAP) even in critically ill COVID-19 patients.

METHODS

In this retrospective, observational study, all critically ill COVID-19 patients who survived for ≥2 days in a single university hospital and had at least one serum procalcitonin (PCT) value and associated blood culture and/or culture from a lower respiratory tract specimen available were eligible for the study.

RESULTS

Over the research period, 184 patients were recruited; 67 VAP/BSI occurred, with an incidence rate of 21.82 episodes of VAP/BSI (95% CI: 17.18-27.73) per 1000 patient-days among patients who were included. At the time of a positive microbiological culture, an average PCT level of 1.25-3.2 ng/mL was found. Moreover, also in subjects without positive cultures, PCT was altered in 21.7% of determinations, with an average value of 1.04-5.5 ng/mL. Both PCT and PCT-72 h were not linked to a diagnosis of VAP/BSI in COVID-19 patients, according to the multivariable GEE models (aOR 1.13, 95% CI 0.51-2.52 for PCT; aOR 1.32, 95% CI 0.66-2.64 for PCT-72 h).

CONCLUSION

Elevated PCT levels might not always indicate bacterial superinfections or coinfections in a severe COVID-19 setting.

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.

Systemic Inflammation after Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is one of the most severe neurological disorders, with a high mortality rate and severe disabling functional sequelae. Systemic inflammation following hemorrhagic stroke may play an important role in mediating intracranial and extracranial tissue damage. Previous studies showed that various systemic inflammatory biomarkers might be useful in predicting clinical outcomes. Anti-inflammatory treatment might be a promising therapeutic approach for improving the prognosis of patients with aSAH. This review summarizes the complicated interactions between the nervous system and the immune system.

AACC Guidance Document on the Clinical Use of Procalcitonin

BACKGROUND

Procalcitonin (PCT), a peptide precursor of the hormone calcitonin, is a biomarker whose serum concentrations are elevated in response to systemic inflammation caused by bacterial infection and sepsis. Clinical adoption of PCT in the United States has only recently gained traction with an increasing number of Food and Drug Administration-approved assays and expanded indications for use. There is interest in the use of PCT as an outcomes predictor as well as an antibiotic stewardship tool. However, PCT has limitations in specificity, and conclusions surrounding its utility have been mixed. Further, there is a lack of consensus regarding appropriate timing of measurements and interpretation of results. There is also a lack of method harmonization for PCT assays, and questions remain regarding whether the same clinical decision points may be used across different methods.

CONTENT

This guidance document aims to address key questions related to the use of PCT to manage adult, pediatric, and neonatal patients with suspected sepsis and/or bacterial infections, particularly respiratory infections. The document explores the evidence for PCT utility for antimicrobial therapy decisions and outcomes prediction. Additionally, the document discusses analytical and preanalytical considerations for PCT analysis and confounding factors that may affect the interpretation of PCT results.

SUMMARY

While PCT has been studied widely in various clinical settings, there is considerable variability in study designs and study populations. Evidence to support the use of PCT to guide antibiotic cessation is compelling in the critically ill and in some lower respiratory tract infections but is lacking in other clinical scenarios, and evidence is also limited in the pediatric and neonatal populations. Interpretation of PCT results requires guidance from multidisciplinary care teams of clinicians, pharmacists, and clinical laboratorians.

Biomarkers for risk stratification and antibiotic stewardship in elderly patients

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Daily combined measurement of platelet count and presepsin concentration can predict in-hospital death of patients with severe coronavirus disease 2019 (COVID-19)

The purpose of this study was to classify patients with severe COVID-19 into more detailed risk groups using coagulation/fibrinolysis, inflammation/immune response, and alveolar/myocardial damage biomarkers, as well as to identify prognostic markers for these patients. These biomarkers were measured every day for eight intensive care unit days in 54 adult patients with severe COVID-19. The patients were classified into survivor (n = 40) and non-survivor (n = 14) groups. Univariate and multivariate analyses showed that the combined measurement of platelet count and presepsin concentrations may be the most valuable for predicting in-hospital death, and receiver operating characteristic curve analysis further confirmed this result (area under the curve = 0.832). Patients were consequently classified into three groups (high-, medium-, and low-risk) on the basis of their cutoff values (platelet count 53 × 10³/µL, presepsin 714 pg/mL). The Kaplan-Meier curve for 90-day survival by each group showed that the 90-day mortality rate significantly increased as risk level increased (P < 0.01 by the log-rank test). Daily combined measurement of platelet count and presepsin concentration may be useful for predicting in-hospital death and classifying patients with severe COVID-19 into more detailed risk groups.

Can we predict critical care mortality with non-conventional inflammatory markers in SARS-CoV-2 infected patients?

BACKGROUND

Severe COVID-19 disease is associated with multiple organ involvement,then failure and often fatal outcomes.In addition,inflammatory mechanisms and cytokine storms,documented in many COVID-19 patients,are responsible for the progression of the disease and high mortality rates.Inflammatory parameters,such as procalcitonin(PCT) and C-reactive protein(CRP), are widely used in clinical practice.

OBJECTIVE

To evaluate the predictive power of non-conventional inflammatory markers regarding mortality risk.

METHODS

In our prospective study 52 patients were followed for 5 days after admission to an intensive care unit immediately with severe SARS-CoV-2 infection.We compared leukocyte-,platelet antisedimentation rate (LAR, PAR),neutrophil lymphocyte ratio(NLR), CRP, PCT levels.

RESULTS

In non-surviving(NSU) patients LAR remained largely constant from D1 to D4 with a statistically significant drop(p <  0.05) only seen on D5.The NSU group showed statistically significant(p <  0.05) elevated LAR medians on D4 and D5, compared to the SU group.NLR values were continually higher in the non-survivor group.The difference between the SU and NSU groups were statistically significant on every examined day.PAR, CRP and PCT levels didn't show any significant differences between the SU and NSU groups.

CONCLUSIONS

In conclusion, this study suggests that LAR and NLR are especially worthy of further investigation as prognostic markers.LAR might be of particular relevance as it is not routinely obtained in current clinical practice.It would seem beneficial to include LAR in data sets to train prognostic artificial intelligence.

Procalcitonin and Adrenomedullin in Infectious Diseases

Calcitonin (CT) and adrenomedullin (ADM) are members of the CT family. Procalcitonin (PCT) is a prohormone of CT. Elevations in serum PCT and ADM levels are associated with severe sepsis and coronavirus disease 2019 (COVID-19). PCT enhances sepsis mortality and it binds to the CGRP receptor, which is a heterodimer of CT receptor-like receptor and receptor activity-modifying protein 1. The N-terminal truncated form of PCT, PCT3-116, is produced by the cleavage of PCT by dipeptidyl peptidase 4 (DPP-4) and is the main form of PCT in serum during sepsis, inducing microvascular permeability. Mid-regional pro-adrenomedullin (MR-proADM) is used instead of ADM as a biological indicator because ADM is rapidly degraded, and MR-proADM is released at the same rate as ADM. ADM reduces endothelial permeability and promotes endothelial stability. Endothelial dysfunction is responsible for multiple organ failure in sepsis and COVID-19 patients. Therefore, ADM may be an important molecule for improving the severity associated with sepsis and COVID-19. This review focuses on the current knowledge of PCT and ADM in sepsis and COVID-19.

Diagnostic and therapeutic value of biomarkers in urosepsis

Urosepsis is sepsis caused by urogenital tract infection and is one of the most common critical illnesses in urology. If urosepsis is not diagnosed early, it can rapidly progress and worsen, leading to increased mortality. In recent years, with the increase of urinary tract surgery, the incidence of urosepsis continues to rise, posing a serious threat to patients. Early diagnosis of urosepsis, timely and effective treatment can greatly reduce the mortality of patients. Biomarkers such as WBC, NLR, PCT, IL-6, CRP, lactate, and LncRNA all play specific roles in the early diagnosis or prognosis of urosepsis. In addition to the abnormal increase of WBC, we should be more alert to the rapid decline of WBC. NLR values were superior to WBC counts alone in predicting infection severity. Compared with several other biomarkers, PCT values can differentiate between bacterial and non-bacterial sepsis. IL-6 always has high sensitivity and specificity for the diagnosis of sepsis, and CRP also has high sensitivity and specificity for the diagnosis of urosepsis. Lactic acid is closely related to the prognosis of patients with urosepsis. LncRNAs may be potential biomarkers of urosepsis. This article summarizes the main biomarkers, hoping to provide a reference for the timely diagnosis and evaluation of urosepsis.

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.

Use of serum procalcitonin (PCT) level and PCT mRNA expression as a potential clinical biomarker in cats with bacterial and viral infections

OBJECTIVES

The aim of this study was to investigate the use of procalcitonin (PCT) as a biomarker in differentiating bacterial infections from viral infections in cats. In addition, the relationship between PCT and mortality rate was also examined.

METHODS

Forty-five cats were included in the study. The cats were categorised into two groups: bacterial (n = 20) and viral (n = 25) infection. Serum PCT level and PCT mRNA expression were analysed from blood samples collected before treatment.

RESULTS

Serum PCT level and PCT mRNA expression of the cats with presumed bacterial infection were higher than those with viral infection (P = 0.001 and P = 0.001, respectively). The receiver operating characteristic (ROC) curve analysis revealed an area under the ROC curve value of 0.888 for serum PCT and 0.850 for PCT mRNA expression. There was no statistically significant difference among respiratory, urinary and gastrointestinal tract infections regarding serum PCT level and PCT mRNA expression in the presumed bacterial infection group (P = 0.741 and P = 0.141, respectively). In the presumed bacterial infection group, serum PCT level and PCT mRNA expression in the non-surviving cats were higher than those of the surviving cats (P = 0.021 and P = 0.026, respectively).

CONCLUSIONS AND RELEVANCE

Serum PCT level and PCT mRNA expression were considered efficient biomarkers in cats to distinguish a bacterial infection from a viral infection. Moreover, ROC curve analysis was highly accurate in the discriminative capacity of these two parameters. PCT level and PCT mRNA expression offer substantial assistance in an efficient therapeutic approach and in avoiding unnecessary antibiotic use in feline clinical practice, particularly in emergency patients and those with non-specific clinical signs, decreasing the mortality rate. However, it should be noted that these data are only research data. More detailed future studies are needed.

Procalcitonin as a predictive marker in COVID-19: A systematic review and meta-analysis

Background

Coronavirus disease 2019 has emerged as a global pandemic causing millions of critical cases and deaths. Early identification of at-risk patients is crucial for planning triage and treatment strategies.

Methods and findings

We performed this systematic review and meta-analysis to determine the pooled prognostic significance of procalcitonin in predicting mortality and severity in patients with COVID-19 using a robust methodology and clear clinical implications.

Design

We used Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Cochrane Handbook for Systematic Reviews of Interventions guidelines. We included thirty-two prospective and retrospective cohort studies involving 13,154 patients.

Results

The diagnostic odds ratio of procalcitonin for predicting mortality were estimated to be 11 (95% CI: 7 to 17) with sensitivity, specificity, and summary area under the curveof 0.83 (95% CI: 0.70 to 0.91), 0.69 (95% CI: 0.58 to 0.79), and 0.83 (95% CI: 0.79 to 0.86) respectively. While for identifying severe cases of COVID-19, the odds ratio was 8.0 (95% CI 5.0 to 12.0) with sensitivity, specificity, and summary area under the curve of 0.73 (95% CI 0.67 to 0.78), 0.74 (0.66 to 0.81), and 0.78 (95% CI 0.74 to 0.82) respectively.

Conclusion

Procalcitonin has good discriminatory power for predicting mortality and disease severity in COVID-19 patients. Therefore, procalcitonin measurement may help identify potentially severe cases and thus decrease mortality by offering early aggressive treatment.

Procalcitonin mediates vascular dysfunction in obesity

AIMS

Obesity is accompanied by a chronic low-grade inflammation associated with endothelial dysfunction and vascular complications. Procalcitonin is a marker of inflammation, secreted by adipose tissue and elevated in obese subjects. We here investigated whether visceral or perivascular fat-derived procalcitonin is a target to improve obesity-induced endothelial dysfunction.

MATERIALS AND METHODS

Procalcitonin expression was identified by Western blot. Murine endothelial cells were isolated using CD31-antibody-coated magnetic beads and reactive oxygen species and nitric oxide (NO) determined by H2DCF- or DAF-FM diacetate loading. Endothelium-dependent vasorelaxation was analyzed using pressure myography of murine arterioles. Calcitonin gene-related peptide (CGRP) was used to activate the calcitonin receptor-like receptor (CRLR)/RAMP1 complex and olcegepant or the dipeptidyl-peptidase 4 (DPP4) inhibitor sitagliptin to block procalcitonin signaling or activation.

KEY FINDINGS

In addition to visceral adipose tissue, procalcitonin was present in perivascular and epicardial tissue. In concentrations typical for obesity, procalcitonin doubled reactive oxygen species formation and decreased endothelial nitric oxide production in murine endothelial cells. Intravenous delivery of procalcitonin to mice in obesity-associated concentrations impaired endothelium-dependent vasorelaxation in a CRLR/RAMP1-dependent manner and antagonized CGRP-induced endothelial NO release in vitro. Use of CRLR/RAMP1-receptor antagonist olcegepant counteracted procalcitonin effects on vasodilation, nitric oxide production and reactive oxygen species formation. Similarly, blocking procalcitonin activation by the DPP4 inhibitor sitagliptin antagonized endothelial procalcitonin effects.

SIGNIFICANCE

Procalcitonin, liberated either from visceral or perivascular adipose tissue, contributes to endothelial dysfunction by antagonizing CGRP signaling in obesity. Targeting hyperprocalcitonemia may be a means to preserve endothelial function and reduce comorbidity burden in obese subjects.

Pathophysiology of Sepsis and Genesis of Septic Shock: The Critical Role of Mesenchymal Stem Cells (MSCs)

The treatment of sepsis and septic shock remains a major public health issue due to the associated morbidity and mortality. Despite an improvement in the understanding of the physiological and pathological mechanisms underlying its genesis and a growing number of studies exploring an even higher range of targeted therapies, no significant clinical progress has emerged in the past decade. In this context, mesenchymal stem cells (MSCs) appear more and more as an attractive approach for cell therapy both in experimental and clinical models. Pre-clinical data suggest a cornerstone role of these cells and their secretome in the control of the host immune response. Host-derived factors released from infected cells (i.e., alarmins, HMGB1, ATP, DNA) as well as pathogen-associated molecular patterns (e.g., LPS, peptidoglycans) can activate MSCs located in the parenchyma and around vessels to upregulate the expression of cytokines/chemokines and growth factors that influence, respectively, immune cell recruitment and stem cell mobilization. However, the way in which MSCs exert their beneficial effects in terms of survival and control of inflammation in septic states remains unclear. This review presents the interactions identified between MSCs and mediators of immunity and tissue repair in sepsis. We also propose paradigms related to the plausible roles of MSCs in the process of sepsis and septic shock. Finally, we offer a presentation of experimental and clinical studies and open the way to innovative avenues of research involving MSCs from a prognostic, diagnostic, and therapeutic point of view in sepsis.

Biomarkers of sepsis in pigs, horses and cattle: from acute phase proteins to procalcitonin

Sepsis is a complex clinical syndrome triggered by an inflammatory host response to an infection. It is usually complicated to detect and diagnose, and has severe consequences in human and veterinary health, especially when treatment is not started early. Therefore, efforts to detect sepsis accurately are needed. In addition, its proper diagnosis could reduce the misuse of antibiotics, which is essential fighting against antimicrobial resistance. This case is a particular issue in farm animals, as antibiotics have been traditionally given massively, but now they are becoming increasingly restricted. When sepsis is suspected in animals, the most frequently used biomarkers are acute phase proteins such as C-reactive protein, serum amyloid A and haptoglobin, but their concentrations can increase in other inflammatory conditions. In human patients, the most promising biomarkers to detect sepsis are currently procalcitonin and presepsin, and there is a wide range of other biomarkers under study. However, there is little information on the application of these biomarkers in veterinary species. This review aims to describe the general concepts of sepsis and the current knowledge about the biomarkers of sepsis in pigs, horses, and cattle and to discuss possible advances in the field.

Usefulness of Procalcitonin as a Predictor of Long-Term Prognosis in the Early Postoperative Period after Esophagectomy for Esophageal Cancer

The aim of this study was to investigate the relationship between serum procalcitonin (PCT) levels after esophagectomy and infectious complications and long-term prognosis. A total of 105 patients who underwent esophagectomy between 2012 and 2019 were stratified into two groups: PCT-High group of ≥1 ng/mL and PCT-Low group of <1 ng/mL. The clinical outcomes and prognostic factors were compared between the two groups 2 postoperative days (POD), 4 POD, and 7 POD after esophagectomy. As the postoperative days passed, the association between PCT and infectious complications became stronger, and the positive predictive value was 100% at 7 POD. At 2 POD, there was no significant association between PCT elevation and infectious complications. Patients in the PCT-Low group had significantly worse overall survival (OS) and recurrence-free survival (RFS) than those in the PCT-High group at 2 POD (p = 0.026 and p = 0.011, respectively). In multivariate analysis, advanced pathological stage (hazard ratio (HR), 5.348; 95% confidence interval (CI), 2.299−12.500; p < 0.001) and PCT-Low group at 2 POD (HR, 3.673; 95% CI, 1.116−12.092; p = 0.032) were also independent predictors of worse OS. PCT in the early postoperative period after esophagectomy could be a good predictor of prognosis.

Cross-Sectional Study of Clinical Predictors of Coccidioidomycosis, Arizona, USA

Demographic and clinical indicators have been described to support identification of coccidioidomycosis; however, the interplay of these conditions has not been explored in a clinical setting. In 2019, we enrolled 392 participants in a cross-sectional study for suspected coccidioidomycosis in emergency departments and inpatient units in Coccidioides-endemic regions. We aimed to develop a predictive model among participants with suspected coccidioidomycosis. We applied a least absolute shrinkage and selection operator to specific coccidioidomycosis predictors and developed univariable and multivariable logistic regression models. Univariable models identified elevated eosinophil count as a statistically significant predictive feature of coccidioidomycosis in both inpatient and outpatient settings. Our multivariable outpatient model also identified rash (adjusted odds ratio 9.74 [95% CI 1.03–92.24]; p = 0.047) as a predictor. Our results suggest preliminary support for developing a coccidioidomycosis prediction model for use in clinical settings.

Elevated Procalcitonin Levels in a Patient With Diabetic Ketoacidosis in the Absence of Infection

Bacterial infections are one of the major precipitating factors in diabetic ketoacidosis (DKA). Procalcitonin (PCT) is highly specific in identifying bacteria sepsis, but PCT may be elevated in patients who do not have sepsis. Here, we report a 25-year-old patient admitted to the ICU for DKA. Initial laboratory investigation showed elevated PCT of 0.87 ng/ml and reached a concentration of 15.88 ng/ml on the second day of admission. PCT levels trended down to 4.7 ng/ml by the third day of admission. This case report shows PCT levels can be increased in patients with DKA even in the absence of infection and PCT levels decrease with clinical improvement of DKA without administration of antibiotics.

Association Between Procalcitonin and Antibiotics in Children With Community-Acquired Pneumonia

OBJECTIVE

To determine whether empirical antibiotic initiation and selection for children with pneumonia was associated with procalcitonin (PCT) levels when results were blinded to clinicians.

METHODS

We enrolled children <18 years with radiographically confirmed pneumonia at 2 children's hospitals from 2014 to 2019. Blood for PCT was collected at enrollment (blinded to clinicians). We modeled associations between PCT and (1) antibiotic initiation and (2) antibiotic selection (narrow versus broad-spectrum) using multivariable logistic regression models. To quantify potential stewardship opportunities, we calculated proportions of noncritically ill children receiving antibiotics who also had a low likelihood of bacterial etiology (PCT <0.25 ng/mL) and those receiving broad-spectrum therapy, regardless of PCT level.

RESULTS

We enrolled 488 children (median PCT, 0.37 ng/mL; interquartile range [IQR], 0.11-2.38); 85 (17%) received no antibiotics (median PCT, 0.32; IQR, 0.09-1.33). Among the 403 children receiving antibiotics, 95 (24%) received narrow-spectrum therapy (median PCT, 0.24; IQR, 0.08-2.52) and 308 (76%) received broad-spectrum (median PCT, 0.46; IQR, 0.12-2.83). In adjusted analyses, PCT values were not associated with antibiotic initiation (odds ratio [OR], 1.02, 95% confidence interval [CI], 0.97%-1.06%) or empirical antibiotic selection (OR 1.07; 95% CI, 0.97%-1.17%). Of those with noncritical illness, 246 (69%) were identified as potential targets for antibiotic stewardship interventions.

CONCLUSION

Neither antibiotic initiation nor empirical antibiotic selection were associated with PCT values. Whereas other factors may inform antibiotic treatment decisions, the observed discordance between objective likelihood of bacterial etiology and antibiotic use suggests important opportunities for stewardship.

SERUM PROCALCITONIN AS A PROGNOSTIC MARKER IN ACUTE SEVERE ULCERATIVE COLITIS: A PROSPECTIVE STUDY

ABSTRACT Background Procalcitonin may be increased in active ulcerative colitis (UC). We investigated the role of procalcitonin in predicting response in acute severe UC (ASUC). Methods Consecutive patients with ASUC diagnosed on basis of Truelove and Witts criteria were enrolled. Serum procalcitonin levels for consecutive patients were measured at admission and day 3. We assessed role of procalcitonin values at presentation and at day 3 in assessing response on day 3 (Oxford’s criteria) and need for second line therapy (day 28). Results Of fifty patients (23 males, mean age: 35.98±13.8 years), 16 did not respond (day 3). Ten (20%) patients required second-line therapy. Baseline procalcitonin was significantly associated with response on day 3 (P=0.016). There was no association between day 1 or day 3 procalcitonin and need for second-line rescue therapy. Conclusion Serial procalcitonin is not an effective biomarker for predicting outcomes or need for second line therapy in ASUC.

High procalcitonin levels associated with increased intensive care unit admission and mortality in patients with a COVID-19 infection in the emergency department

Background

Patients with a severe COVID-19 infection often require admission at an intensive care unit (ICU) when they develop acute respiratory distress syndrome (ARDS). Hyperinflammation plays an important role in the development of ARDS in COVID-19. Procalcitonin (PCT) is a biomarker which may be a predictor of hyperinflammation. When patients with COVID-19 are in the emergency department (ED), elevated PCT levels could be associated with severe COVID-19 infections. The goal of this study is to investigate the association between PCT levels and severe COVID-19 infections in the ED.

Methods

This was a retrospective cohort study including patients with a confirmed COVID-19 infection who visited the ED of Erasmus Medical Center in Rotterdam, the Netherlands, between March and December 2020. The primary outcome was a severe COVID-19 infection, which was defined as patients who required ICU admission, all cause in-hospital mortality and mortality within 30 days after hospital discharge. PCT levels were measured during the ED visit. We used logistic regression to calculate the odds ratio (OR) with 95% confidence interval (95% CI) and corresponding area under the curve (AUC) of PCT on a severe COVID-19 infection, adjusting for bacterial coinfections, age, sex, comorbidities, C-reactive protein (CRP) and D-dimer.

Results

A total of 332 patients were included in the final analysis of this study, of which 105 patients reached the composite outcome of a severe COVID-19 infection. PCT showed an unadjusted OR of 4.19 (95%CI: 2.52–7.69) on a severe COVID-19 infection with an AUC of 0.82 (95% CI: 0.76–0.87). Corrected for bacterial coinfection, the OR of PCT was 4.05 (95% CI: 2.45–7.41). Adjusted for sex, bacterial coinfection, age any comorbidity, CRP and D-dimer, elevated PCT levels were still significantly associated with a severe COVID-19 infection with an adjusted OR of 2.11 (95% CI: 1.36–3.61). The AUC of this multivariable model was 0.85 (95%CI: 0.81–0.90).

Conclusion

High PCT levels are associated with high rates of severe COVID-19 infections in patients with a COVID-19 infection in the ED. The routine measurement of PCT in patients with a COVID-19 infection in the ED may assist physicians in the clinical decision making process regarding ICU disposition.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07144-5.

Diagnostic levels of sepsis biomarkers in children with oncological diseases

The data on the diagnostic levels of sepsis markers in blood plasma in 117 patients with oncological diseases at the age from 1 to 18 years are presented. The patients were divided into 4 groups depending on the outcome of the clinical course of the inflammatory process or infectious complications: group 1 - patients with no complications of anticancer treatment (n = 13/11.1%), group 2 - the presence of a systemic inflammatory response in patients (n = 64/54.7%), group 3 - patients with sepsis (n = 27/23.1%), group 4 - patients with septic shock (n = 13/11.1%). The threshold level of presepsin between groups 1 and 2 was 202 pg/ml, 371 pg/ml between groups 1 and 3, 604 pg/ml between groups 2 and 3 and 1500 pg/ml between groups 3 and 4. For procalcitonin, the threshold level between groups 1and 2 was 0.23 ng/ml, 0.48 ng/ml between groups 1 and 3, 0.51 ng/ml between groups 2 and 3 and 3.9 ng/ml between groups 3 and 4. The threshold value of C-reactive protein in patients with solid tumors was 12.6 g/l between groups 1 and 2. In patients with oncohematological diseases, the threshold level of C-reactive protein was 43.4 g / L between groups 2 and 3, 77.1 g / L between groups 2 and 4. According to the ROC analysis, presepsin was superior to procalcitonin and C-reactive protein in the diagnosis of septic complications.

C-reactive protein-guided use of procalcitonin in COVID-19

Background

A low procalcitonin (PCT) concentration facilitates exclusion of bacterial co-infections in COVID-19, but high costs associated with PCT measurements preclude universal adoption. Changes in inflammatory markers, including C-reactive protein (CRP), can be concordant, and predicting low PCT concentrations may avoid costs of redundant tests and support more cost-effective deployment of this diagnostic biomarker.

Objectives

To explore whether, in COVID-19, low PCT values could be predicted by the presence of low CRP concentrations.

Methods

Unselected cohort of 224 COVID-19 patients admitted to hospital that underwent daily PCT and CRP measurements as standard care. Both 0.25 ng/mL and 0.5 ng/mL were used as cut-offs for positive PCT test results. Geometric mean was used to define high and low CRP values at each timepoint assessed.

Results

Admission PCT was <0.25 ng/mL in 160/224 (71.4%), 0.25–0.5 ng/mL in 27 (12.0%) and >0.5 ng/mL in 37 (16.5%). Elevated PCT was associated with increased risk of death (P = 0.0004) and was more commonly associated with microbiological evidence of bacterial co-infection (P < 0.0001). For high CRP values, significant heterogeneity in PCT measurements was observed, with maximal positive predictive value of 50% even for a PCT cut-off of 0.25 ng/mL. In contrast, low CRP was strongly predictive of low PCT concentrations, particularly <0.5 ng/mL, with a negative predictive value of 97.6% at time of hospital admission and 100% 48 hours into hospital stay.

Conclusions

CRP-guided PCT testing algorithms can reduce unnecessary PCT measurement and costs, supporting antimicrobial stewardship strategies in COVID-19.

Mining of a Clinical Database: The Interpretation of Intense Serial Procalcitonin in the Prediction for Bloodstream Infection

Background: Procalcitonin (PCT) is a promising biomarker for predicting infection. Bloodstream infection (BSI) is usually a deteriorating stage of sepsis. The purpose of this study was to explore the predictive value of intense serial PCT assays for BSI in the intensive care unit (ICU). Methods: This study was a retrospective study based on a clinical database. We analyzed the data of critically ill patients from February 2016 to May 2020. The patients who received PCT assays and blood cultures (BCs) were classified into four groups according to the BCs: (i) BC negative, (ii) bacteria positive, (iii) fungi-positive, and (iv) combined-positive, and the patients with bacteremia were further subdivided into Gram+ and Gram- bacteremia. Results: The database included 11,219 patients. There were 3,593 patients who met the criteria for the analysis. The PCT concentration differed significantly across BC groups (p < 0.0001). The fluctuation of PCT significantly increased in the BC positive groups (p < 0.0001). According to the receiver operating characteristic (ROC), the optimum cutoff of the fluctuation of PCT was around 8 ng/ml for predicting BSI. Conclusion: Our study indicated that the fluctuation of PCT could be an indicator for screening BSI, but less accurate for Gram-positive infections. With a fluctuation of PCT less than 8 ng/ml, BSI should not be a rational cause for sepsis exacerbating.

Clinical utility of procalcitonin and its association with pathogenic microorganisms

In this review, we summarize the relationship of PCT with pathogens, evaluate the clinical utility of PCT in the diagnosis of clinical diseases, condition monitoring and evaluation, and guiding medical decision-making, and explore current knowledge on the mechanisms by which pathogens cause changes in PCT levels. The lipopolysaccharides of the microorganisms stimulate cytokine production in host cells, which in turn stimulates production of serum PCT. Pathogens have different virulence mechanisms that lead to variable host inflammatory responses, and differences in the specific signal transduction pathways result in variable serum PCT concentrations. The mechanisms of signal transduction have not been fully elucidated. Further studies are necessary to ascertain the PCT fluctuation range of each pathogen. PCT levels are helpful in distinguishing between certain pathogens, in deciding if antibiotics are indicated, and in monitoring response to antibiotics.

Immunochromatography-Application Example and POCT Type Genetic Testing

Membrane-based rapid test reagents including immunochromatography are widely used in clinical practice. Recently, high-sensitive reagents based on the immunochromatography method, such as silver amplification method and time resolved fluorescence method for influenza testing, has been developed and early confirmation of infection can be achieved. Furthermore, genetic testing, automated all the steps from extraction till detection, is getting popular. Genetic testing of mycoplasma by Smart Gene Myco system and Coronavirus disease 2019 (COVID-19) test is a good example of membrane-based rapid test reagents. This system uses silica particle-containing membrane filter and enable to shorten the assay time by automates pre-treatment process for removing contamination substances in the sample which affect polymerase-chain-reaction amplification. We hope utilized genetic testing application will help quick confirmation of COVID-19 positive patient and prevent the collapse of medical system under COVID-19 development.

Procalcitonin for individualizing antibiotic treatment: an update with a focus on COVID-19

Procalcitonin (PCT) is useful for differentiating between viral and bacterial infections and for reducing the unnecessary use of antibiotics. As the rise of antimicrobial resistance reaches “alarming” levels according to the World Health Organization, the importance of using biomarkers, such as PCT to limit unnecessary antibiotic exposure has further increased. Randomized trials in patients with respiratory tract infections have shown that PCT has prognostic implications and its use, embedded in stewardship protocols, leads to reductions in the use of antibiotics in different clinical settings without compromising clinical outcomes. However, available data are heterogeneous and recent trials found no significant benefit. Still, from these trials, we have learned several key considerations for the optimal use of PCT, which depend on the clinical setting, severity of presentation, and pretest probability for bacterial infection. For patients with respiratory infections and sepsis, PCT can be used to determine whether to initiate antimicrobial therapy in low-risk settings and, together with clinical data, whether to discontinue antimicrobial therapy in certain high-risk settings. There is also increasing evidence regarding PCT-guided therapy in patients with coronavirus disease 2019 (COVID-19). This review provides an up-to-date overview of the use of PCT in different clinical settings and diseases, including a discussion about its potential to improve the care of patients with COVID-19.

The Urosepsis-A Literature Review

Urosepsis is a very serious condition with a high mortality rate. The immune response is in the center of pathophysiology. The therapeutic management of these patients includes surgical treatment of the source of infection, antibiotic therapy and life support. The management of this pathology is multidisciplinary and requires good collaboration between the urology, intensive care, imaging and laboratory medicine departments. An imbalance of pro and anti-inflammatory cytokines produced during sepsis plays an important role in pathogenesis. The study of cytokines in sepsis has important implications for understanding pathophysiology and for development of other therapeutic solutions. If not treated adequately, urosepsis may lead to serious septic complications and organ sequelae, even to a lethal outcome.

Biomarkers in Chronic Obstructive Pulmonary Disease: Emerging Roles of Eosinophils and Procalcitonin

Antibiotics can improve the prognosis in patients with exacerbation of chronic obstructive pulmonary disease. However, the overuse of antibiotics can carry serious adverse effects for patients (gastrointestinal infections) and for society (bacterial resistance). Likewise, systemic corticosteroids may also help these patients, but also carries severe adverse effects like osteoporosis, muscle loss, and diabetes, in many patients. Whenever safe methods exist to reduce these two treatment modalities, they should be implemented. The blood biomarkers procalcitonin and the fraction of leukocytes known as eosinophil granulocytes have been proven in randomized controlled trials (RCTs), to effectively, significantly, and substantially assist in reducing the use of these two potent, yet toxic medication types. In this review, the background and main clinical results are discussed, explaining the rationale for biomarker-guided clinical decisions. Also, the main expected effects, their sizes, and importantly the limitations to such a strategy are described. Clinical evidence is prioritized with main weight on RCTs and meta-analyses of these and regarding outcomes, and focus is set on the safety of such a biomarker-guided strategy, as well as the effects on medicine reduction. In an epoch of increasing demands to physicians from patients and politicians to cure and reduce symptoms, the Hippocratic phrase of "primum non nocere" or "first, do no harm" seems more than ever of contemporary importance.

Biomarker-Guided Individualization of Antibiotic Therapy

Treatment failure of antibiotic therapy due to insufficient efficacy or occurrence of toxicity is a major clinical challenge, and is expected to become even more urgent with the global rise of antibiotic resistance. Strategies to optimize treatment in individual patients are therefore of crucial importance. Currently, therapeutic drug monitoring plays an important role in optimizing antibiotic exposure to reduce treatment failure and toxicity. Biomarker-based strategies may be a powerful tool to further quantify and monitor antibiotic treatment response, and reduce variation in treatment response between patients. Host response biomarkers, such as CRP, procalcitonin, IL-6, and presepsin, could potentially carry significant information to be utilized for treatment individualization. To achieve this, the complex interactions among immune system, pathogen, drug, and biomarker need to be better understood and characterized. The purpose of this tutorial is to discuss the use and evidence of currently available biomarker-based approaches to inform antibiotic treatment. To this end, we also included a discussion on how treatment response biomarker data from preclinical, healthy volunteer, and patient-based studies can be further characterized using pharmacometric and system pharmacology based modeling approaches. As an illustrative example of how such modeling strategies can be used, we describe a case study in which we quantitatively characterize procalcitonin dynamics in relation to antibiotic treatments in patients with sepsis.

Comparing machine learning algorithms for predicting ICU admission and mortality in COVID-19

As predicting the trajectory of COVID-19 is challenging, machine learning models could assist physicians in identifying high-risk individuals. This study compares the performance of 18 machine learning algorithms for predicting ICU admission and mortality among COVID-19 patients. Using COVID-19 patient data from the Mass General Brigham (MGB) Healthcare database, we developed and internally validated models using patients presenting to the Emergency Department (ED) between March-April 2020 (n = 3597) and further validated them using temporally distinct individuals who presented to the ED between May-August 2020 (n = 1711). We show that ensemble-based models perform better than other model types at predicting both 5-day ICU admission and 28-day mortality from COVID-19. CRP, LDH, and O2 saturation were important for ICU admission models whereas eGFR <60 ml/min/1.73 m2, and neutrophil and lymphocyte percentages were the most important variables for predicting mortality. Implementing such models could help in clinical decision-making for future infectious disease outbreaks including COVID-19.

A Procalcitonin and C-Reactive Protein-Guided Clinical Pathway for Reducing Antibiotic Use in Children Hospitalized with Bronchiolitis

Despite the lack of evidence that bronchodilators, corticosteroids, and antibiotics are useful in treating bronchiolitis, their use is still widespread. This study aimed to determine the consumption of antibiotics for bronchiolitis before and after a procalcitonin-guided clinical pathway (CP) implementation. In December 2019, a CP for lower respiratory tract infection management was implemented at the Department of Women's and Children's Health at Padua University Hospital. This was a pre-post, quasi-experimental study that assessed the changes in the treatment of bronchiolitis during two bimesters preceding the CP implementation (pre-period: January 2018-February 2018 and January 2019-February 2019) and during the bimester after CP implementation (post-period January 2020-February 2020). After the CP implementation, there was a significant reduction in antibiotic prescriptions from 36.2% to 12.5% (p = 0.036) in patients hospitalized for bronchiolitis. Co-amoxiclav treatment, the antibiotic most commonly administered, decreased from 66.6% to 33.3%. Among outpatients' bronchiolitis episodes, a statistically significant decrease in beta2-agonists' use (from 18.0% to 4.4%, pre and post periods) and a quasi-significant decrease in corticosteroid use (from 8.0% to 0% pre and post periods) were observed. An evidence-based CP supported by educational lectures was associated with significant changes in the physicians' prescribing habits.

A Remarkable Elevation in the Procalcitonin Levels Due to Diabetic Ketoacidosis in a Hemodialysis Patient

Procalcitonin (PCT), a marker of the inflammatory response during infections, can be elevated by diabetic ketoacidosis (DKA). A male patient in his 50s with diabetic nephropathy on hemodialysis presented with vomiting and a reduced level of consciousness and was diagnosed with DKA. His PCT level was markedly elevated, but bacterial cultures (blood, urine, and stool) were negative. The PCT level decreased after DKA improvement. In this patient, DKA probably enhanced the PCT levels. As DKA can increase the PCT levels, an elevation of the PCT levels in DKA patients may not be indicative of infectious diseases, and non-infectious causes of DKA should therefore be considered.

Limited Utility of Procalcitonin in Identifying Community-Associated Bacterial Infections in Patients Presenting with Coronavirus Disease 2019

The role of procalcitonin in identifying community-associated bacterial infections among patients with coronavirus disease 2019 is not yet established. In 2,443 patients with 148 bacterial coinfections, mean procalcitonin levels were significantly higher with any bacterial infection (13.16 ± 51.19 ng/ml; P = 0.0091) and with bacteremia (34.25 ± 85.01 ng/ml; P = 0.0125) than without infection (2.00 ± 15.26 ng/ml).

The role of procalcitonin in identifying community-associated bacterial infections among patients with coronavirus disease 2019 is not yet established. In 2,443 patients of whom 148 had bacterial coinfections, mean procalcitonin levels were significantly higher with any bacterial infection (13.16 ± 51.19 ng/ml; P = 0.0091) and with bacteremia (34.25 ± 85.01 ng/ml; P = 0.0125) than without infection (2.00 ± 15.26 ng/ml). Procalcitonin (cutoff, 0.25 or 0.50 ng/ml) did not reliably identify bacterial coinfections but may be useful in excluding bacterial infection.

Neglected Variables in the Interpretation of Serum Procalcitonin Levels in Patients With Septic Shock

The interpretation of serum procalcitonin (PCT) levels in septic patients is facilitated by reviewing the known stimuli that activate the PCT family of genes. Herein we describe 7 pathways that, alone or in combination, can increase serum PCT levels. As a marker of activation of innate immunity, high PCT levels affect clinical diagnosis, can be trended as a measure of "source" control, and can guide duration of antibacterial therapy in septic patients. Low PCT levels reflect little to no activation of an innate immune response, influence the differential diagnosis, and support the discontinuation of empiric antibiotic therapy. Understanding the pathways that result in elevated serum PCT levels is necessary for interpretation and subsequent clinical management.