Clinical review 167: Procalcitonin and the calcitonin gene family of peptides in inflammation, infection, and sepsis: a journey from calcitonin back to its precursors

Navigating the Modern Landscape of Sepsis: Advances in Diagnosis and Treatment

Sepsis poses a significant threat to human health due to its high morbidity and mortality rates worldwide. Traditional diagnostic methods for identifying sepsis or its causative organisms are time-consuming and contribute to a high mortality rate. Biomarkers have been developed to overcome these limitations and are currently used for sepsis diagnosis, prognosis prediction, and treatment response assessment. Over the past few decades, more than 250 biomarkers have been identified, a few of which have been used in clinical decision-making. Consistent with the limitations of diagnosing sepsis, there is currently no specific treatment for sepsis. Currently, the general treatment for sepsis is conservative and includes timely antibiotic use and hemodynamic support. When planning sepsis-specific treatment, it is important to select the most suitable patient, considering the heterogeneous nature of sepsis. This comprehensive review summarizes current and evolving biomarkers and therapeutic approaches for sepsis.

Fibroblast growth factor 23 is pumping iron: C-terminal-fibroblast growth factor 23 cleaved peptide and its function in iron metabolism

PURPOSE OF REVIEW

Iron deficiency regulates the production of the bone-derived phosphaturic hormone fibroblast growth factor 23 (FGF23) but also its cleavage, to generate both intact (iFGF23) and C-terminal (Cter)-FGF23 peptides. Novel studies demonstrate that independently of the phosphaturic effects of iFGF23, Cter-FGF23 peptides play an important role in the regulation of systemic iron homeostasis. This review describes the complex interplay between iron metabolism and FGF23 biology.

RECENT FINDINGS

C-terminal (Cter) FGF23 peptides antagonize inflammation-induced hypoferremia to maintain a pool of bioavailable iron in the circulation. A key mechanism proposed is the down-regulation of the iron-regulating hormone hepcidin by Cter-FGF23.

SUMMARY

In this manuscript, we discuss how FGF23 is produced and cleaved in response to iron deficiency, and the principal functions of cleaved C-terminal FGF23 peptides. We also review possible implications anemia of chronic kidney disease (CKD).

Procalcitonin, brain natriuretic peptide and albumin as markers to predict prognosis in hospitalized older Japanese patients with a risk of infection

AIM

Whether serum concentration of procalcitonin (PCT), brain natriuretic peptide (BNP) and albumin (Alb) have an association with the outcome of hospitalized older patients is unclear. We investigated clinical outcomes and any predictive factors in hospitalized Japanese older patients with a risk of infection.

METHODS

In the retrospective study, 820 Japanese patients were followed up for 30 days or until death. During the observation period, 656 patients survived and 164 patients died. The predictive factors of death were analyzed according to demographic and clinical variables.

RESULTS

The survival rate was decreased as the serum PCT increased from <0.5 to ≥10 ng/mL, as was also the case with BNP from <300 to ≥300 pg./mL, whereas low Alb (<2.5 g/dL) showed a lower survival rate than high Alb (≥2.5 g/dL; P < 0.01). Using the Cox regression model, the multivariable-adjusted hazard ratios (95% confidence interval) were as follows: PCT 0.5-2 versus <0.5 ng/mL: 1.61(1.04-2.49), PCT 2-10 versus <0.5 ng/mL: 1.91(1.15-3.16), PCT ≥10 versus <0.5 ng/mL: 2.90(1.84-4.59), high BNP 1.26 (0.89-1.76) and low Alb 0.68 (0.52-0.87). The mortality rate increased as the number of scores (PCT + BNP + Alb) increased.

CONCLUSIONS

Concentration-dependent high PCT, high BNP and low Alb were positive risk factors associated with poor prognosis in hospitalized older patients with a risk of infection. Geriatr Gerontol Int 2024; 24: 571-576.

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.

Association of inflammatory biomarkers with overall survival in burn patients: a systematic review and meta-analysis

INTRODUCTION

The inflammatory response to burn injuries can lead to organ dysfunction that ultimately results in increased mortality and morbidity. This meta-analysis was conducted to determine the efficacy of inflammatory biomarkers, including the neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), procalcitonin (PCT), and C-reactive protein (CRP) as predictive tools of mortality among burn patients.

MATERIAL AND METHODS

The biomarker levels of survivors and non-survivors were consolidated according to guidelines for Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Three main databases were searched electronically: PubMed, Web of Science, and Scopus, on December 8, 2022. The Newcastle-Ottawa Quality Assessment Scale (NOS) was used to evaluate and score the methodological quality of the included studies. The standard mean difference (SMD) with a 95% confidence interval (CI) was utilized.

RESULTS

Twenty-four studies were included in our systematic review and meta-analysis, (3636 total burn patients), of whom 2878 survived. We found that deceased burn patients had elevated levels of NLR (SMD = 0.60, 95% CI; 0.19-1.00, P < 0.001), CRP (SMD = 0.80, 95% CI; 0.02-1.58, P = 0.04), and PCT (SMD = 0.85, 95% CI; 0.45-1.24, P < 0.001), compared to survivors. However, we found no association between PLR and mortality among burn patients (SMD = 0.00, 95% CI; -0.14-0.15, P < 0.001). In addition, CRP was significantly higher in non-survivors (SMD = 0.80, 95% CI; 0.02-1.58, P =0.04). Similar results were also found about PCT (SMD = 0.85, 95% CI; 0.45-1.24, P < 0.001). When we analyzed the PCT data, collected in the first 24-48 hours, we found similar results; the PCT level was significantly higher in non-survivors in the immediate postinjury-period (SMD = 0.67, 95% CI; 0.31-1.02, P < 0.001). There was no publication bias among studies on the role of NLR in burn (Egger's test P = 0.91). The based cut-off values for NLR (13), CRP (71), and PCT (1.77) yielded sensitivities of 69.2%, 100%, and 93.33%, and specificities of 76%, 72.22%, and 72.22% respectively.

DISCUSSION/CONCLUSIONS

PCT is a marker of sepsis, therefore its elevated level is presumably associated with a higher incidence and severity of sepsis among non-survivors. In addition, NLR and CRP are promising biomarkers for predicting and guiding prevention against burn deaths in clinical settings.

Perioperative pancreaticoduodenectomy management strategy focusing on postoperative early drain colonization

PURPOSE

Pancreatoduodenectomy (PD) is a highly invasive procedure. Intra-abdominal infections and pancreatic fistulas are strongly correlated complications. In the present study, we identified the risk factors for postoperative early drain colonization (POEDC) and established a perioperative management strategy.

METHODS

A total of 205 patients who underwent pancreatoduodenectomy were included in the study. POEDC was defined as a positive drain fluid culture before postoperative day (POD) 4. We retrospectively investigated the correlation between POEDC, postoperative outcomes, and clinical factors.

RESULTS

POEDC was observed in 26 patients (12.6%) with poor postoperative outcomes, including pancreatic fistulas (P < 0.001). A multivariate analysis demonstrated a correlation between these postoperative outcomes and the age (P = 0.002), body mass index (BMI) (P = 0.002), procalcitonin (PCT) level (P < 0.001), and drain amylase level on POD 1 (P = 0.032). Enterococcus was detected most frequently, being found in 15 patients.

CONCLUSION

We observed a strong correlation between POEDC and poor postoperative outcomes. The BMI, age, and PCT and drain amylase level on POD 1 should be considered POEDC risk factors, with the need to propose an antibiotic perioperative strategy. POEDC control may represent the key to improving postoperative outcomes after PD.

Construction and external validation of a scoring prediction model for mortality risk within 30 days of community-acquired pneumonia in children admitted to the pediatric intensive care unit: A multicenter retrospective case-control study

In this study, we constructed and validated a scoring prediction model to identify children admitted to the pediatric intensive care unit (PICU) with community-acquired pneumonia (CAP) at risk for early death. Children with CAP who were admitted to the PICU were included in the training set and divided into death and survival groups according to whether they died within 30 days of admission. For univariate and multifactorial analyses, demographic characteristics, vital signs at admission, and laboratory test results were collected separately from the 2 groups, and independent risk factors were derived to construct a scoring prediction model. The ability of the scoring model to predict CAP-related death was validated by including children with CAP hospitalized at 3 other centers during the same period in the external validation set. Overall, the training and validation sets included 296 and 170 children, respectively. Univariate and multifactorial analyses revealed that procalcitonin (PCT), lactate dehydrogenase (LDH), activated partial thromboplastin time (APTT), and fibrinogen (Fib) were independent risk factors. The constructed scoring prediction model scored 2 points each for PCT ≥ 0.375 ng/mL, LDH ≥ 490 U/L, and APTT ≥ 31.8 s and 1 point for Fib ≤ 1.78 g/L, with a total model score of 0-7 points. When the score was ≥ 5 points, the sensitivity and specificity of mortality diagnosis in children with CAP were 72.7% and 87.5%, respectively. In the external validation set, the sensitivity, specificity, and accuracy of the scoring model for predicting the risk of CAP-related death were 64.0%, 92.4%, and 88.2%, respectively. Constructing a scoring prediction model is worth promoting and can aid pediatricians in simply and rapidly evaluating the risk of death in children with CAP, particularly those with complex conditions.

The Sensitivity and Specificity of Procalcitonin in Diagnosing Bacterial Sepsis in Neonates

CONTEXT AND OBJECTIVES

Neonatal sepsis accounts for 15% of all neonatal deaths. Early detection enables prompt administration of antibiotic treatment, reducing morbidity and mortality. This study aims to review the sensitivity and specificity of procalcitonin in diagnosing microbiologically-proven sepsis in neonates to determine the optimal procalcitonin cut-off value for use in clinical practice.

DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION

Medline, EMBASE and PubMed were searched on 3 May 2023 for original studies in symptomatic neonates in whom both blood culture and procalcitonin levels were taken, and a procalcitonin cut-off with either sensitivity or specificity reported. Studies that included asymptomatic or culture-negative neonates in the proven sepsis group were excluded. Risk of bias was assessed using the Qualitative Assessment of Diagnostic Accuracy Studies 2 tool.

RESULTS

Nineteen original studies enrolling a total of 1920 symptomatic neonates (721 with proven sepsis) were included. Six studies used a procalcitonin cut-off of 0.5 ng/mL and found a sensitivity of 87% to 100% and specificity of 17% to 89%. Nine studies evaluated higher procalcitonin cut-off values between 0.99 ng/mL and 2 ng/mL, which were 67% to 98% sensitive and 41% to 89% specific. All other procalcitonin thresholds were neither sensitive nor specific. Meta-analysis was not performed because of high risk of bias within the identified studies.

CONCLUSIONS

This review found that procalcitonin was highly sensitive (87% to 100%) at a cut-off value of 0.5 ng/mL, although specificity varied greatly across all cut-off values reviewed. The variation in diagnostic accuracy between studies suggests that procalcitonin may be useful to guide antibiotic cessation but should not be used alone as a diagnostic marker for neonatal sepsis.

The Development and Evaluation of a Prediction Model for Kidney Transplant-Based Pneumocystis carinii Pneumonia Patients Based on Hematological Indicators

BACKGROUND

This study aimed to develop a simple predictive model for early identification of the risk of adverse outcomes in kidney transplant-associated Pneumocystis carinii pneumonia (PCP) patients.

METHODS

This study encompassed 103 patients diagnosed with PCP, who received treatment at our hospital between 2018 and 2023. Among these participants, 20 were categorized as suffering from severe PCP, and, regrettably, 13 among them succumbed. Through the application of machine learning techniques and multivariate logistic regression analysis, two pivotal variables were discerned and subsequently integrated into a nomogram. The efficacy of the model was assessed via receiver operating characteristic (ROC) curves and calibration curves. Additionally, decision curve analysis (DCA) and a clinical impact curve (CIC) were employed to evaluate the clinical utility of the model. The Kaplan-Meier (KM) survival curves were utilized to ascertain the model's aptitude for risk stratification.

RESULTS

Hematological markers, namely Procalcitonin (PCT) and C-reactive protein (CRP)-to-albumin ratio (CAR), were identified through machine learning and multivariate logistic regression. These variables were subsequently utilized to formulate a predictive model, presented in the form of a nomogram. The ROC curve exhibited commendable predictive accuracy in both internal validation (AUC = 0.861) and external validation (AUC = 0.896). Within a specific threshold probability range, both DCA and CIC demonstrated notable performance. Moreover, the KM survival curve further substantiated the nomogram's efficacy in risk stratification.

CONCLUSIONS

Based on hematological parameters, especially CAR and PCT, a simple nomogram was established to stratify prognostic risk in patients with renal transplant-related PCP.

Chitosan modified graphene field-effect transistor biosensor for ultrasensitive procalcitonin detection

Sepsis is a systemic inflammatory response caused by a bacterial infection that often leading to tissue damage, organ failure and death. Procalcitonin (PCT), as a peptide precursor to hormones, is the main biomarker to identification of the sepsis. In this study, a chitosan modified graphene field transistor (CTS-GFET) was established and first time used for PCT ultra-sensitive detection. CTS was functionalized on the GFET channel surface to immobilized anti-PCT by glutaraldehyde. This biosensor exhibited the detection limit as low as 0.82 ag/mL in PBS, which exhibited 3 times enhancement compared with GFET biosensors. The enhancement mechanisms of CTS-GFET were studied by electrical theoretical model. In addition, the CTS-GFET biosensor was successfully applied to quantify the concentration of the PCT in human serum samples, indicating the potential use in clinical application.

Nanobiosensors for procalcitonin (PCT) analysis

BACKGROUND

Procalcitonin (PCT) is a critical biomarker that is released in response to bacterial infections and can be used to differentiate the pathogenesis of the infectious process.

OBJECTIVE

In this article, we provide an overview of recent advances in PCT biosensors, highlighting different approaches for biosensor construction, different immobilization methods, advantages and roles of different matrices used, analytical performance, and PCT biosensor construction. Also, we will explain PCT biosensors sensible limits of detection (LOD), linearity, and other analytical characteristics. Future prospects for the development of better PCT biosensor systems are also discussed.

METHODS

Traditional methods such as capillary electrophoresis, high-performance liquid chromatography, and mass spectrometry are effective in analyzing PCT in the medical field, but they are complicated, time-consuming sample preparation, and require expensive equipment and skilled personnel.

RESULTS

In the past decades, PCT biosensors have emerged as simple, fast, and sensitive tools for PCT analysis in various fields, especially medical fields.

CONCLUSION

These biosensors have the potential to accompany or replace traditional analytical methods by simplifying or reducing sample preparation and making field testing easier and faster, while significantly reducing the cost per analysis.

Improved hemophagocytic lymphohistiocytosis index predicts prognosis of adult Epstein-Barr virus-associated HLH patients

BACKGROUND

Epstein-Barr virus (EBV)-associated hemophagocytic lymphohistiocytosis (EBV-HLH) is a common subtype of HLH with heterogeneous clinical presentations from self-limited to death, of which adults are worse than children.

OBJECTIVE

To establish predictors of mortality risk in adult EBV-HLH patients for timely and appropriate treatment.

METHODS

Patients with confirmed EBV-HLH admitted to Beijing Friendship Hospital from January 2015 to December 2019 were enrolled and statistical analysis of their laboratory test results was performed.

RESULTS

Among 246 adult patients with EBV-HLH, the deceased were older (p < 0.05), with fewer blood cells (p < 0.05), poorer renal function (p < 0.01), higher levels of procalcitonin (PCT) (p < 0.01), as well as soluble interleukin-2 receptor (sCD25) (p < 0.01). The overall median survival time of patients was 135 days, 87 days for patients without transplantation and 294 days with transplantation (p < 0.001). A combined index of sCD25, PCT, and estimated glomerular filtration rate (eGFR) was obtained to predict prognosis, named the Improved HLH index (IH index), and patients were divided into three groups meeting IH- (i.e. sCD25 ≤ 18,000 pg/mL, PCT ≤ 1.8 ng/mL, eGFR ≥ 90 mL/min/1.73m²), IH1+ (i.e. only sCD25 > 18,000 pg/mL or only eGFR < 90 mL/min/1.73m²), and IH2+ (i.e. the rest), respectively. In patients with the HScore ≥ 169 or meeting HLH-04, those meeting IH2+ had significantly worse prognoses than those who met IH1+ or IH- (p < 0.001). In the group meeting IH + or IH2+, patients who received allo-HSCT had better prognoses than those who did not (p < 0.05), but there was still a significant difference in prognosis among the three groups in transplanted patients (p < 0.001).

CONCLUSION

The IH index can early identify adult patients with a poor prognosis of EBV-HLH, initiating timely and appropriate treatment.KEY MESSAGESA combined index of sCD25, PCT, and eGFR was obtained to predict prognosis, named the Improved Hemophagocytic Lymphohistiocytosis index (IH index).IH index can early identify adult patients with a poor prognosis of EBV-HLH, initiating timely and appropriate treatment.

Procalcitonin kinetics following abdominal aortic surgery and its value for postoperative intestinal ischaemia detection

OBJECTIVE

The purpose of our study was to describe perioperative kinetics of procalcitonin (PCT) in patients undergoing aortic surgery, to compare the kinetics in the open abdominal aortic aneurysm (AAA) repair and aortobifemoral bypass for aortoiliac occlusive disease (AIOD), and to evaluate the ability of PCT to detect intestinal ischaemia.

METHODS

A prospective non-randomized observational cohort study in 80 patients (62 men and 18 women) undergoing elective aortic surgery was performed. Serum PCT was measured at baseline and defined intraoperative and postoperative timepoints up to postoperative day 7. MRI contrast-enhanced imaging was used to detect intestinal ischaemia.

RESULTS

The comparison of the AAA and AIOD cohort did not show any significant difference in PCT levels. Patients with intestinal ischaemia had higher serum PCT at multiple timepoints postoperatively. The most accurate timepoints for early diagnosis were postoperative day 3, followed by 24 h after declamping of the vascular reconstruction, and postoperative day 7. The sensitivity and negative predictive values were 100% in all mentioned timepoints. However, event at the best timepoint the specificity was 89% and the positive predictive value 43%.

CONCLUSIONS

Procalcitonin levels in the postoperative period at proper timepoints might help to detect postoperative intestinal ischaemia. The limitation of this marker is its low specificity for intestinal ischaemia and low positive predictive value. The highest value of this marker is that it can rule out this complication because normal PCT levels mean that intestinal ischaemia is very unlikely.

Procalcitonin is elevated in severe malaria and is a promising biomarker of severe malaria and multi-organ dysfunction: A cross-sectional study and meta-analysis

BACKGROUND

Elevated procalcitonin (PCT) has been reported in bacterial infection and is positively associated with the severity of the disease. Patients with severe Plasmodium falciparum malaria also display higher procalcitonin levels compared to those with non-severe disease, indicating a possible role for bacterial infection in severe disease, however this observation remained variable in different study population. Furthermore, the significance of PCT in different clinical categories of severe malaria has not been evaluated so far.

METHODS

A total of 74 P. falciparum-infected subjects were enrolled in the study comprising of 55 cases complicated malaria [cerebral malaria- 14; non-cerebral severe malaria- 21; multi-organ dysfunction- 20] and 19 uncomplicated cases. Serum levels of PCT were quantified by fluorescence immunoassay. For meta-analysis, the literature search was performed in different databases, and all relevant articles were screened, and eligible reports were identified based on predefined inclusion and exclusion criteria. The meta-analysis was performed by comprehensive meta-analysis software V3 and MedCalc 20.218.

RESULTS

Patients with severe P. falciparum malaria had significantly higher PCT levels compared to uncomplicated cases (p = 0.01). Analysis of PCT in different categories of patients with severe malaria revealed significantly elevated PCT in multi-organ dysfunctions compared to those with uncomplicated malaria (p = 0.004) and cerebral malaria (p = 0.05). Interestingly the receiver operating characteristics curve analysis showed procalcitonin as a promising biomarker for differentiating severe malaria (AUC: 0.697, p = 0.01) and multi-organ dysfunction (AUC: 0.704, p = 0.007) from uncomplicated malaria and other clinical categories of falciparum malaria, respectively. Furthermore, meta-analysis also revealed an elevated procalcitonin in severe malaria and it could be an important biomarker in the management of severe disease.

CONCLUSIONS

PCT is elevated in P. falciparum-infected patients and could be a good biomarker for diagnosis of severe malaria and multi-organ dysfunction. It can help in the management of severe disease with additional treatment options.

Diagnostic value of serum procalcitonin and C-reactive protein in discriminating between bacterial and nonbacterial colitis: a retrospective study

BACKGROUND

Differentiating between bacterial and nonbacterial colitis remains a challenge. We aimed to evaluate the value of serum procalcitonin (PCT) and C-reactive protein (CRP) in differentiating between bacterial and nonbacterial colitis.

METHODS

Adult patients with three or more episodes of watery diarrhea and colitis symptoms within 14 days of a hospital visit were eligible for this study. The patients' stool pathogen polymerase chain reaction (PCR) testing results, serum PCT levels, and serum CRP levels were analyzed retrospectively. Patients were divided into bacterial and nonbacterial colitis groups according to their PCR. The laboratory data were compared between the two groups. The area under the receiver operating characteristic curve (AUC) was used to evaluate diagnostic accuracy.

RESULTS

In total, 636 patients were included; 186 in the bacterial colitis group and 450 in the nonbacterial colitis group. In the bacterial colitis group, Clostridium perfringens was the commonest pathogen (n=70), followed by Clostridium difficile toxin B (n=60). The AUC for PCT and CRP was 0.557 and 0.567, respectively, indicating poor discrimination. The sensitivity and specificity for diagnosing bacterial colitis were 54.8% and 52.6% for PCT, and 52.2% and 54.2% for CRP, respectively. Combining PCT and CRP measurements did not increase the discrimination performance (AUC, 0.522; 95% confidence interval, 0.474-0.571).

CONCLUSION

Neither PCT nor CRP helped discriminate bacterial colitis from nonbacterial colitis.

Comparison of monocyte distribution width and Procalcitonin as diagnostic markers for sepsis: Meta-analysis of diagnostic test accuracy studies

AIM

We aimed to perform a meta-analysis to find out whether PCT and MDW could be used as accurate diagnostic markers for sepsis.

METHODS

We searched PUBMED, WOS, and SCOPUS databases. Inclusion criteria were any observational or clinical trials that compared monocyte Distribution Width [MDW] with Procalcitonin [PCT] as diagnostic markers in a patient with sepsis. Case reports, editorials, conference abstracts, and animal studies were excluded. RevMan software [5.4] was used to perform the meta-analysis.

RESULTS

After the complete screening, 5 observational studies were included in the meta-analysis. The total number of patients included in the meta-analysis in the sepsis group is 565 and 781 in the control group. The pooled analysis between the sepsis group and controls showed a statistically significant association between sepsis and increased levels of MDW and PCT [MD = 3.94, 95% CI = 2.53 to 5.36, p-value < 0.00001] and [MD = 9.29, 95% CI = 0.67 to 17.91, p-value = 0.03] respectively. Moreover, the subgroup analysis showed that the p-value of MDW levels [< 0.00001] is more significant than the p-value of PCT levels = 0.03, the p-value between the two subgroups [< 0.00001]. Additionally, the overall ROC Area for MDW [0.790] > the overall ROC Area for PCT [0.760].

CONCLUSION

Our study revealed a statistically significant association between sepsis and increased MDW and PCT levels compared with controls and the overall ROC Area for MDW is higher than the overall ROC Area for PCT, indicating that the diagnostic accuracy of MDW is higher than PCT.MDW can be used as a diagnostic marker for sepsis patients in the emergency department. More multicenter studies are needed to support our findings.

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.

Effects of procalcitonin on antimicrobial treatment decisions in patients with coronavirus disease 2019 (COVID-19)

OBJECTIVE

To describe the natural course of procalcitonin (PCT) in patients with coronavirus disease 2019 (COVID-19) and the correlation between PCT and antimicrobial prescribing to provide insight into best practices for PCT data utilization in antimicrobial stewardship in this population.

DESIGN

Single-center, retrospective, observational study.

SETTING

Michigan Medicine.

PATIENTS

Inpatients aged ≥18 years hospitalized March 1, 2020, through October 31, 2021, who were positive for severe acute respiratory coronavirus virus 2 (SARS-CoV-2), with ≥1 PCT measurement. Exclusion criteria included antibiotics for nonpulmonary bacterial infection on admission, treatment with azithromycin only for chronic obstructive pulmonary disease (COPD) exacerbation, and pre-existing diagnosis of cystic fibrosis with positive respiratory cultures.

METHODS

A structured query was used to extract data. For patients started on antibiotics, bacterial pneumonia (bPNA) was determined through chart review. Multivariable models were used to assess associations of PCT level and bPNA with antimicrobial use.

RESULTS

Of 793 patients, 224 (28.2%) were initiated on antibiotics: 33 (14.7%) had proven or probable bPNA, 125 (55.8%) had possible bPNA, and 66 (29.5%) had no bPNA. Patients had a mean of 4.1 (SD, ±5.2) PCT measurements if receiving antibiotics versus a mean of 2.0 (SD, ±2.6) if not. Initial PCT level was highest for those with proven/probable bPNA and was associated with antibiotic initiation (odds ratio 95% confidence interval [CI], 1.17-1.30). Initial PCT (rate ratio [RR] 95% CI, 1.01-1.08), change in PCT over time (RR 95% CI, 1.01-1.05), and bPNA group (RR 95% CI, 1.23-1.84) were associated with antibiotic duration.

CONCLUSIONS

PCT trends are associated with the decision to initiate antibiotics and duration of treatment, independent of bPNA status and comorbidities. Prospective studies are needed to determine whether PCT level can be used to safely make decisions regarding antibiotic treatment for 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.

Differentiating infection, colonisation, and sterile inflammation in critical illness: the emerging role of host-response profiling

Infection results when a pathogen produces host tissue damage and elicits an immune response. Critically ill patients experience immune activation secondary to both sterile and infectious insults, with overlapping clinical phenotypes and underlying immunological mechanisms. Patients also undergo a shift in microbiota with the emergence of pathogen-dominant microbiomes. Whilst the combination of inflammation and microbial shift has long challenged intensivists in the identification of true infection, the advent of highly sensitive molecular diagnostics has further confounded the diagnostic dilemma as the number of microbial detections increases. Given the key role of the host immune response in the development and definition of infection, profiling the host response offers the potential to help unravel the conundrum of distinguishing colonisation and sterile inflammation from true infection. This narrative review provides an overview of current approaches to distinguishing colonisation from infection using routinely available techniques and proposes matrices to support decision-making in this setting. In searching for new tools to better discriminate these states, the review turns to the understanding of the underlying pathobiology of the host response to infection. It then reviews the techniques available to assess this response in a clinically applicable context. It will cover techniques including profiling of transcriptome, protein expression, and immune functional assays, detailing the current state of knowledge in diagnostics along with the challenges and opportunities. The ultimate infection diagnostic tool will likely combine an assessment of both host immune response and sensitive pathogen detection to improve patient management and facilitate antimicrobial stewardship.

Procalcitonin as a biomarker of nosocomial pneumonia in aneurysmal subarachnoid hemorrhage patients treated in neuro-ICU

BACKGROUND

Nosocomial pneumonia commonly develops in aneurysmal subarachnoid hemorrhage (aSAH) patients and is associated with poor prognosis of these patients. This study is designed to verify the predictive value of procalcitonin (PCT) on nosocomial pneumonia in aSAH patients.

METHODS

298 aSAH patients received treatments in the neuro-intensive care unit (NICU) of West China hospital were included. Logistic regression was conducted to verify the association between PCT level and nosocomial pneumonia and to construct a model for predicting pneumonia. Area under the receiver operating characteristic curve (AUC) were calculated to evaluate the accuracy of the single PCT and the constructed model.

RESULTS

90 (30.2%) patients developed pneumonia during hospitalizations among included aSAH patients. Pneumonia group had higher procalcitonin level (p < 0.001) than non-pneumonia group. The mortality (p < 0.001), mRS (p < 0.001), length of ICU stay (p < 0.001), length of hospital stay (p < 0.001) were both higher or longer in pneumonia group. Multivariate logistic regression indicated WFNS (p = 0.001), acute hydrocephalus (p = 0.007), WBC (p = 0.021), PCT (p = 0.046) and C-reactive protein (CRP) (p = 0.031) were independently associated with the development of pneumonia in included patients. The AUC value of procalcitonin for predicting nosocomial pneumonia was 0.764. Composed of WFNS, acute hydrocephalus, WBC, PCT and CRP, the predictive model for pneumonia has higher AUC of 0.811.

CONCLUSIONS

PCT is an available and effective predictive marker of nosocomial pneumonia in aSAH patients. Composed of WFNS, acute hydrocephalus, WBC, PCT and CRP, our constructed predictive model is helpful for clinicians to evaluate the risk of nosocomial pneumonia and guide therapeutics in aSAH patients.

The rapid detection of procalcitonin in septic serum using immunoaffinity MALDI chips

BACKGROUND

Sepsis is a common worldwide health condition with high mortality. It is caused by a dysregulated immune response to the pathogen. Severe infections resulting in sepsis can be also determined by monitoring several bloodstream biomarkers, one of them being pro-hormone procalcitonin (PCT). PCT concentration in the bloodstream correlates well with sepsis and in severe cases increases up to a thousand times from the healthy physiological values in a short time. In this study, we developed a rapid technique for PCT detection by MALDI-TOF mass spectrometry, that uses in-situ enrichment directly on the specialized immuno MALDI chips that are utilized as MALDI plates. The method's ability to detect PCT was confirmed by comparing the results with LC-MS bottom-up workflow. The new method detects intact PCT by its m/z and uncovers its alternations in septic serum.

METHODS

The MALDI chips used for the detection of PCT were prepared by ambient ion soft landing of anti-PCT antibody on an ITO glass slide. The chips were used for the development of the rapid MALDI-TOF MS method. A parallel method based on affinity enrichment on magnetic beads followed by LC-MS/MS data-dependent peptide microsequencing was used to prove PCT presence in the sample. All samples were also tested by ELISA to determine PCT concentration prior to analyzing them by mass spectrometry methods.

RESULTS

The MALDI chip method was optimized using recombinant PCT spiked into the human serum. The PCT detection limit was 10 ng/mL. The optimized method was used to analyze 13 sera from patients suffering sepsis. The PCT results were confirmed by LC-MS/MS. The measurement of the intact PCT by the MALDI chip method revealed that sera of patients with severe sepsis have other forms of PCT present, which show post-processing of the primary sequence by cleavage of PCT, resulting in the formation of N and C termini fragments.

CONCLUSIONS

Procalcitonin from human serum was successfully enriched and detected using immunoaffinity MALDI chips. The intact PCT was characterized in 13 septic patients. The method is more specific compared to non-MS-based immunoaffinity techniques and allows observation of different variants of PCT in septic patients.

Aminoprocalcitonin protects against hippocampal neuronal death via preserving oxidative phosphorylation in refractory status epilepticus

Refractory status epilepticus (RSE) is a neurological emergency where sustaining seizure causes severe neuronal death. Currently, there is no available neuroprotectant effective in RSE. Aminoprocalcitonin (NPCT) is a conserved peptide cleaved from procalcitonin, but its distribution and function in the brain remain enigmatic. Survival of neurons relies on sufficient energy supply. Recently, we found that NPCT was extensively distributed in the brain and had potent modulations on neuronal oxidative phosphorylation (OXPHOS), suggesting that NPCT might be involved in neuronal death by regulating energy status. In the present study, combining biochemical and histological methods, high-throughput RNA-sequence, Seahorse XFe analyser, an array of mitochondria function assays, and behavior-electroencephalogram (EEG) monitoring, we investigated the roles and translational values of NPCT in neuronal death after RSE. We found that NPCT was extensively distributed throughout gray matters in rat brain while RSE triggered NPCT overexpression in hippocampal CA3 pyramidal neurons. High-throughput RNA-sequence demonstrated that the influences of NPCT on primary hippocampal neurons were enriched in OXPHOS. Further function assays verified that NPCT facilitated ATP production, enhanced the activities of mitochondrial respiratory chain complexes I, IV, V, and increased neuronal maximal respiration capacity. NPCT exerted multiple neurotrophic effects including facilitating synaptogenesis, neuritogenesis, spinogenesis, and suppression of caspase-3. A polyclonal NPCT immunoneutralization antibody was developed to antagonize NPCT. In the in vitro 0-Mg²⁺ seizure model, immunoneutralization of NPCT caused more neuronal death, while exogenous NPCT supplementation, though did not reverse death outcomes, preserved mitochondrial membrane potential. In rat RSE model, both peripheral and intracerebroventricular immunoneutralization of NPCT exacerbated hippocampal neuronal death and peripheral immunoneutralization increased mortality. Intracerebroventricular immunoneutralization of NPCT further led to more serious hippocampal ATP depletion, and significant EEG power exhaustion. We conclude that NPCT is a neuropeptide regulating neuronal OXPHOS. During RSE, NPCT was overexpressed to protect hippocampal neuronal survival via facilitating energy supply.

An Unrecognized Cause of Elevated Procalcitonin Level

Diabetic Ketoacidosis (DKA) is a preventable yet serious complication of diabetes that is commonly associated with type 1 diabetes but can also occur in other forms of diabetes, including type 2. Infection is a primary cause of DKA and can lead to elevated levels of procalcitonin (PCT), which is a biomarker used to differentiate bacterial infections from non-infectious inflammation. However, some cases of DKA have shown increased PCT levels even in the absence of bacterial infection, and the underlying mechanism of this observation is not fully understood. To gain a better understanding of how non-infectious inflammation affects PCT levels, further research is needed. While PCT is a helpful biomarker, it should be interpreted in the context of the patient's overall clinical picture, including signs and symptoms of infection or inflammation and underlying medical conditions that may be contributing to their presentation. A systematic approach to evaluating and managing patients with DKA can minimize the risk of unnecessary antibiotic use and ensure optimal treatment. We present a 31-year-old male who was admitted to the ICU with DKA, and further investigations revealed elevated PCT levels. Despite conducting several studies and cultures, including blood and urine, no infections were detected. The patient was treated for DKA with hydration and insulin administration without the use of antibiotics, and his PCT levels subsequently decreased.

The association between migraines and periodontal disease: A systematic review of clinical studies

BACKGROUND

Recent studies have postulated several hypotheses explaining the association between migraines and periodontitis. We aimed to systematically review and assess if there is an association between inflammatory mediators in migraines and periodontal disease. Indexed database search was performed from inception up to and including April 2022. Data such as study design, study grouping, participants, age, sex, migraine characteristics, assessment criteria for periodontitis and outcomes were collected. Methodological index for non-randomized studies was used to assess the risk of bias. The systematic analysis format was personalized to review the appropriate information.

HIGHLIGHTS

Levels of pro-inflammatory mediators such as serum procalcitonin, leptin, calcitonin gene related peptide and interleukin-6 were elevated in patients with chronic periodontitis and migraines.

CONCLUSION

Chronic periodontitis may be a contributing factor for migraines. However, future standardized studies are required to understand the true relationship at a clinical and molecular level. This may better help in managing patients with comorbid conditions in the future.

Inactivation of the gene encoding procalcitonin prevents antibody-mediated arthritis

BACKGROUND

Procalcitonin (PCT) is applied as a sensitive biomarker to exclude bacterial infections in patients with rheumatoid arthritis (RA) flare-ups. Beyond its diagnostic value, little is known about the pathophysiological role of PCT in RA.

METHODS

Collagen antibody-induced arthritis (CAIA) was induced in Calca-deficient mice (Calca^-/-), lacking PCT (n = 15), and wild-type (WT) mice (n = 13), while control (CTRL) animals (n = 8 for each genotype) received phosphate-buffered saline. Arthritis severity and grip strength were assessed daily for 10 or 48 days. Articular inflammation, cartilage degradation, and bone lesions were assessed by histology, gene expression analysis, and µ-computed tomography.

RESULTS

Serum PCT levels and intra-articular PCT expression increased following CAIA induction. While WT animals developed a full arthritic phenotype, Calca-deficient mice were protected from clinical and histological signs of arthritis and grip strength was preserved. Cartilage turnover markers and Tnfa were exclusively elevated in WT mice. Calca-deficient animals expressed increased levels of Il1b. Decreased bone surface and increased subchondral bone porosity were observed in WT mice, while Calca-deficiency preserved bone integrity.

CONCLUSION

The inactivation of Calca and thereby PCT provided full protection from joint inflammation and arthritic bone loss in mice exposed to CAIA. Together with our previous findings on the pathophysiological function of Calca-derived peptides, these data indicate an independent pro-inflammatory role of PCT in RA.

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.

Performance Comparison of Procalcitonin, Delta Neutrophil Index, C-Reactive Protein, and Serum Amyloid A Levels in Patients with Hematologic Diseases

(1) Background: We compared the diagnostic and prognostic performance of serum amyloid A (SAA), procalcitonin (PCT), delta neutrophil index (DNI), and C-reactive protein (CRP) in patients with hematologic diseases; (2) Methods: We retrospectively collected the remaining serum samples from patients with hematologic diseases, analyzed their clinical data, and measured the levels of PCT, DNI, CRP, and SAA. Performances for infection diagnosis were evaluated using a receiver operating characteristic curve analysis, and 90-day mortality was analyzed using Kaplan-Meier estimation; (3) Results: The levels of all markers were significantly higher in the infected group (N = 27) than those in the uninfected group (N = 100) (p < 0.0001 for all markers). The areas under the curve for diagnosing infection for PCT, DNI, CRP, and SAA were 0.770, 0.817, 0.870, and 0.904, respectively. Increased PCT levels were associated with higher mortality (p = 0.0250); this association was not observed with other examined markers; (4) Conclusions: CRP and SAA exhibited greater discriminative power for infection than PCT. However, only PCT levels were positively associated with 90-day mortality. Herein, we evaluated the diagnostic performance of the four markers. Additional studies are needed to confirm the findings of the present study and validate the potential of these markers in clinical practice.

Procalcitonin for the early discrimination of fever etiology in patients with systemic autoimmune diseases attending the emergency department

In febrile patients with known systemic autoimmune disease, early discrimination between infection and disease flare often represents a clinical challenge. This study aimed at evaluating the efficacy of procalcitonin (PCT) and other common inflammatory biomarkers in discriminating disease flare from bacterial infections in the Emergency Department (ED). In a cross-sectional observational retrospective study, we identified consecutive febrile patients with a known diagnosis of systemic autoimmune disease, admitted to the ED, and subsequently hospitalized. Flare vs infective disease was defined on clinical records at hospital discharge. Dosage of common inflammatory markers was performed at ED admission. Out of 177 patients, those with infection were most commonly elderly, frail, and with reduced peripheral oxygen saturation at admission. When compared to C-reactive protein (CRP) and white blood count (WBC), PCT showed the best performance in discriminating infections vs flare. However, only at a very high threshold value of 2 ng/ml, the PCT had a satisfactory negative predictive value of 88.9%, although with a very low specificity of 13.6% and a positive predictive value of 35.8%. Our data suggest that in the ED setting, the early PCT determination has low accuracy in the differentiation of disease flare from infection in patients with known rheumatologic disease. However, the PCT could be useful in elderly and comorbid subjects, in supporting clinical assessment and in recognizing those febrile patients needing prompt antibiotic treatment.

Refining empiric subgroups of pediatric sepsis using machine-learning techniques on observational data

Sepsis contributes to 1 of every 5 deaths globally with 3 million per year occurring in children. To improve clinical outcomes in pediatric sepsis, it is critical to avoid "one-size-fits-all" approaches and to employ a precision medicine approach. To advance a precision medicine approach to pediatric sepsis treatments, this review provides a summary of two phenotyping strategies, empiric and machine-learning-based phenotyping based on multifaceted data underlying the complex pediatric sepsis pathobiology. Although empiric and machine-learning-based phenotypes help clinicians accelerate the diagnosis and treatments, neither empiric nor machine-learning-based phenotypes fully encapsulate all aspects of pediatric sepsis heterogeneity. To facilitate accurate delineations of pediatric sepsis phenotypes for precision medicine approach, methodological steps and challenges are further highlighted.

Case report: Ewing sarcoma with EWSR-ERG fusion elevates procalcitonin extremely in the long term without infection

Background

Ewing sarcoma (ES) represents a rare, aggressive bone and soft-tissue cancer. Unlike breast, liver, pancreatic, and prostate cancers, Ewing sarcoma has had no representative tumor marker until now. The use of procalcitonin (PCT) as a tumor marker is also rarely reported. PCT is a clinically recognized and widely used inflammatory marker in recent years. In rare cases, PCT may also be falsely positive due to non-infectious factors. In the few previously reported papers regarding the correlation between tumors and PCT, we learned that abnormalities of PCT level can also be impacted by individual cancers.

Case presentation

Here, we first reported a case of Ewing sarcoma with markedly elevated PCT without infection and carried out some literature review. The patient was a middle-aged man with extraskeletal Ewing sarcoma whose lesion was located in the distal abdominal ileum. He had a sudden and unprovoked onset of high fever during chemotherapy before surgery. After multiple examinations, the patient's blood routine, C-reactive protein, blood culture, and CT examination showed no signs of infection, and even the culture from the end of the central venous catheter showed no pathogen growth. Only PCT increased dramatically to more than 200 ng/ml. PCT remained at this level for several months until a single abdominal lumpectomy was performed before it dropped to near-normal levels.

Conclusion

In our report, PCT is significantly elevated in Ewing sarcoma in the absence of infection. Not only that, but we particularly highlighted the precipitous drop in PCT following tumor resection.

Other markers of medullary thyroid cancer, not only calcitonin

BACKGROUND

Medullary thyroid cancer (MTC) is a rare neuroendocrine tumor originating from parafollicular C-cells. It represents 2% of all thyroid malignancies and 0.4-1.4% of all thyroid nodules. MTC has a variable clinical course, with complete remission often difficult to achieve. An early diagnosis is still crucial in MTC management, enabling a radical surgical treatment, the only chance for curing the patient. Calcitonin (Ct) is a very sensitive MTC tumor marker in patients with thyroid nodules, although Ct-negative MTCs have been described, but not all clinical guidelines recommend the Ct routine measurement in thyroid nodules because of the absolute low prevalence of MTC in the general population and the consequent scarce positive predictive value of Ct. Moreover, the specificity of moderately high Ct levels is not high. Thus, the scientific community has been investigating the possible role of other tumor markers for MTC diagnosis and prognosis.

AIM OF THE REVIEW

The present review is an attempt to summarize the knowledge available today on the role of other serum markers for MTC alternative to Ct.

CONCLUSIONS

At present, literature data does not seem solid enough yet to establish effective flowcharts in evaluating a thyroid nodule for MTC, involving alternative serum markers, particularly in cases of moderately high CT levels. MTC is a rare diagnosis in thyroid nodules, and this makes the evaluation of any tumor serum marker accuracy problematic. More extensive and prospective studies are needed to shed more light on this intriguing challenge.

Clinical Utility of Procalcitonin on Antibiotic Stewardship: A Narrative Review

Procalcitonin (PCT) was discovered as a useful marker for bacterial infection. Following its discovery, there have been a substantial number of clinical studies conducted to evaluate the presence of bacterial infections, and to guide antibiotic treatment by the stratified levels of PCT. Clinical evidence suggests that antibiotic treatment by PCT-guided antibiotic stewardship has been associated with a reduction in antibiotic usage without an increase in adverse outcomes. The use of PCT was approved by the Food and Drug Administration in the United States of America in 2017 to guide antibiotic treatment in sepsis and lower respiratory tract infections (LRTIs). In Korea, the use of PCT for sepsis and for pneumonia was approved in 2015 and 2022, respectively. This review will discuss the clinical utility of PCT on antibiotic stewardship in the management of sepsis and LRTIs including 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.

Current Status of Antibiotic Stewardship and the Role of Biomarkers in Antibiotic Stewardship Programs

The importance of antibiotic stewardship is increasingly emphasized in accordance with the increasing incidences of multidrug-resistant organisms and accompanying increases in disease burden. This review describes the obstacles in operating an antibiotic stewardship program (ASP), and whether the use of biomarkers within currently available resources can help. Surveys conducted around the world have shown that major obstacles to ASPs are shortages of time and personnel, lack of appropriate compensation for ASP operation, and lack of guidelines or appropriate manuals. Sufficient investment, such as the provision of full-time equivalent ASP practitioners, and adoption of computerized clinical decision systems are useful measures to improve ASP within an institution. However, these methods are not easy in terms of both time commitments and cost. Some biomarkers, such as C-reactive protein, procalcitonin, and presepsin are promising tools in ASP due to their utility in diagnosis and forecasting the prognosis of sepsis. Recent studies have demonstrated the usefulness of algorithmic approaches based on procalcitonin level to determine the initiation or discontinuation of antibiotics, which would be helpful in decreasing antibiotics use, resulting in more appropriate antibiotics use.

Biomarkers as point-of-care tests to guide prescription of antibiotics in people with acute respiratory infections in primary care

BACKGROUND

Acute respiratory infections (ARIs) are by far the most common reason for prescribing an antibiotic in primary care, even though the majority of ARIs are of viral or non-severe bacterial aetiology. It follows that in many cases antibiotic use will not be beneficial to a patient's recovery but may expose them to potential side effects. Furthermore, limiting unnecessary antibiotic use is a key factor in controlling antibiotic resistance. One strategy to reduce antibiotic use in primary care is point-of-care biomarkers. A point-of-care biomarker (test) of inflammation identifies part of the acute phase response to tissue injury regardless of the aetiology (infection, trauma, or inflammation) and may be used as a surrogate marker of infection, potentially assisting the physician in the clinical decision whether to use an antibiotic to treat ARIs. Biomarkers may guide antibiotic prescription by ruling out a serious bacterial infection and help identify patients in whom no benefit from antibiotic treatment can be anticipated. This is an update of a Cochrane Review first published in 2014.

OBJECTIVES

To assess the benefits and harms of point-of-care biomarker tests of inflammation to guide antibiotic treatment in people presenting with symptoms of acute respiratory infections in primary care settings regardless of patient age.

SEARCH METHODS

We searched CENTRAL (2022, Issue 6), MEDLINE (1946 to 14 June 2022), Embase (1974 to 14 June 2022), CINAHL (1981 to 14 June 2022), Web of Science (1955 to 14 June 2022), and LILACS (1982 to 14 June 2022). We also searched three trial registries (10 December 2021) for completed and ongoing trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in primary care patients with ARIs that compared the use of point-of-care biomarkers with standard care. We included trials that randomised individual participants, as well as trials that randomised clusters of patients (cluster-RCTs).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data on the following primary outcomes: number of participants given an antibiotic prescription at index consultation and within 28 days follow-up; participant recovery within seven days follow-up; and total mortality within 28 days follow-up. We assessed risk of bias using the Cochrane risk of bias tool and the certainty of the evidence using GRADE. We used random-effects meta-analyses when feasible. We further analysed results with considerable heterogeneity in prespecified subgroups of individual and cluster-RCTs.

MAIN RESULTS

We included seven new trials in this update, for a total of 13 included trials. Twelve trials (10,218 participants in total, 2335 of which were children) evaluated a C-reactive protein point-of-care test, and one trial (317 adult participants) evaluated a procalcitonin point-of-care test. The studies were conducted in Europe, Russia, and Asia. Overall, the included trials had a low or unclear risk of bias. However all studies were open-labelled, thereby introducing high risk of bias due to lack of blinding. The use of C-reactive protein point-of-care tests to guide antibiotic prescription likely reduces the number of participants given an antibiotic prescription, from 516 prescriptions of antibiotics per 1000 participants in the control group to 397 prescriptions of antibiotics per 1000 participants in the intervention group (risk ratio (RR) 0.77, 95% confidence interval (CI) 0.69 to 0.86; 12 trials, 10,218 participants; I² = 79%; moderate-certainty evidence).  Overall, use of C-reactive protein tests also reduce the number of participants given an antibiotic prescription within 28 days follow-up (664 prescriptions of antibiotics per 1000 participants in the control group versus 538 prescriptions of antibiotics per 1000 participants in the intervention group) (RR 0.81, 95% CI 0.76 to 0.86; 7 trials, 5091 participants; I² = 29; high-certainty evidence). The prescription of antibiotics as guided by C-reactive protein tests likely does not reduce the number of participants recovered, within seven or 28 days follow-up (567 participants recovered within seven days follow-up per 1000 participants in the control group versus 584 participants recovered within seven days follow-up per 1000 participants in the intervention group) (recovery within seven days follow-up: RR 1.03, 95% CI 0.96 to 1.12; I² = 0%; moderate-certainty evidence) (recovery within 28 days follow-up: RR 1.02, 95% CI 0.79 to 1.32; I² = 0%; moderate-certainty evidence). The use of C-reactive protein tests may not increase total mortality within 28 days follow-up, from 1 death per 1000 participants in the control group to 0 deaths per 1000 participants in the intervention group (RR 0.53, 95% CI 0.10 to 2.92; I² = 0%; low-certainty evidence). We are uncertain as to whether procalcitonin affects any of the primary or secondary outcomes because there were few participants, thereby limiting the certainty of evidence. We assessed the certainty of the evidence as moderate to high according to GRADE for the primary outcomes for C-reactive protein test, except for mortality, as there were very few deaths, thereby limiting the certainty of the evidence.

AUTHORS' CONCLUSIONS

The use of C-reactive protein point-of-care tests as an adjunct to standard care likely reduces the number of participants given an antibiotic prescription in primary care patients who present with symptoms of acute respiratory infection. The use of C-reactive protein point-of-care tests likely does not affect recovery rates. It is unlikely that further research will substantially change our conclusion regarding the reduction in number of participants given an antibiotic prescription, although the size of the estimated effect may change.  The use of C-reactive protein point-of-care tests may not increase mortality within 28 days follow-up, but there were very few events. Studies that recorded deaths and hospital admissions were performed in children from low- and middle-income countries and older adults with comorbidities.  Future studies should focus on children, immunocompromised individuals, and people aged 80 years and above with comorbidities. More studies evaluating procalcitonin and potential new biomarkers as point-of-care tests used in primary care to guide antibiotic prescription are needed.  Furthermore, studies are needed to validate C-reactive protein decision algorithms, with a specific focus on potential age group differences.

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.

Serum Procalcitonin Levels in Newly Diagnosed Hodgkin Lymphoma: Correlation with Other Inflammatory Biomarkers

Background and Objectives: Procalcitonin (PCT) is a useful biomarker for the diagnosis of sepsis. Inflammatory markers are elevated in patients with Hodgkin lymphoma (HL), and yet ongoing infection rarely coexists at diagnosis. PCT levels might be helpful in differentiating bacterial from disease-related inflammation. Materials and Methods: We evaluated serum PCT levels and other inflammation markers in newly diagnosed HL patients. Values < 0.50 ng/mL were considered normal (0.10−0.50 ng/mL: detectable, <0.10 ng/mL: undetectable), while values ≥ 0.50 ng/L were considered elevated. Results: Among 137 patients, 55 had B symptoms (40%), 77/130 (59%) had elevated Erythrocyte Sedimentation Rate (ESR) and 116 (85%) had elevated C-Reactive Protein (CRP) (median 38.1 mg/L (range; 2.97−328)). PCT levels were normal in most patients (undetectable 94/137 (68.5%) and detectable 41/137(30%)) with median value < 0.10 ng/mL (range; <0.10−15.90). Elevated PCT was recorded in only two patients (1.5%). Patients with PCT < 0.10 ng/mL had significantly lower median CRP (25.75; range (2.97−203.0)) compared to patients with PCT ≥ 0.1 ng/mL (median CRP 92.50 mg/L; range (3.34−328.0)). Almost all patients (40/41, 97.6%) with detectable PCT had elevated CRP. Conclusions: This is the first study showing that the inflammation characterizing HL is not associated with PCT elevations, although CRP levels are elevated in 85% of the patients. Normal PCT levels may rule out the possibility of occult infection, thus preventing extensive evaluation, which may delay treatment initiation.

The Etiology of Community-Acquired Pneumonia Correlates with Serum Inflammatory Markers in Children

Community-acquired pneumonia (CAP) severely affects pediatric hospitalizations. This study assessed the contribution of CAP to hospitalizations, its etiology in relationship with age, and the inflammatory markers. Between 2013 and 2018, 1064 CAP patients were hospitalized and diagnosed with bacterial/possibly bacterial pneumonia (BP), viral/possibly viral pneumonia (VP) and atypical pneumonia (AP). The etiology was confirmed using blood/pleural fluid culture/polymerase chain reaction (PCR), rapid antigen test/PCR in nasopharyngeal swabs, or serological studies. CAP accounted for 9.9% of hospitalizations and 14.8% of patient days. BP was diagnosed in 825 (77.5%), VP in 190 (17.9%), and AP in 49 (4.6%) cases; the confirmed etiology (n = 209; 20%) included mostly influenza (39%; n = 82), respiratory syncytial virus (RSV, 35%; n = 72), and Mycoplasma pneumoniae (19%; n = 39). VP frequency decreased with age (41% in < 3 mo to 9% in ≥ 60 mo), in contrast to AP (13% in ≥ 60 mo). Among the analyzed parameters, the best differentiating potential was shown by: C-reactive protein (CRP, AUCBP-VP = 0.675; 95% CI: 0.634−0.715), procalcitonin (AUCBP-AP = 0.73; 95% CI: 0.67−0.794), and CRP/procalcitonin (AUCAP-VP = 0.752; 95% CI: 0.67−0.83); a good positive predictive value (88.8%, 98.3%, and 91.6%, respectively) but a low negative predictive value (29.5%, 13.1%, and 40.7%, respectively) was observed. CAP influences hospital patient days more than the crude number of patients would suggest. On a clinical basis, BP is mainly recognized, although viral pneumonia is confirmed most often. RSV and influenza are responsible for a huge percentage of hospitalized cases, as well as M. pneumoniae in children aged ≥ 5 years. Serum inflammatory markers may help differentiate etiological factors.

A Review of Adrenomedullin in Pediatric Patients: A Useful Biomarker

Adrenomedullin has several properties. It acts as a potent vasodilator, has natriuretic effects, and reduces endothelial permeability. It also plays a role in initiating the early hyperdynamic phase of sepsis. Since its discovery, many articles have been published studying the uses and benefits of this biomarker. The aim of this review is to determine the usefulness of adrenomedullin in pediatric patients. Relevant studies covering adrenomedullin in pediatrics (<18 years) and published up until August 2021 were identified through a search of MEDLINE, PubMed, Embase, Web of Science, Scopus, and Cochrane. Seventy studies were included in the present review, most of them with a low level of evidence (IV to VI). Research on adrenomedullin has primarily been related to infection and the cardiovascular field. The performance of adrenomedullin to quantify infection in children seems satisfactory, especially in sepsis. In congenital heart disease, this biomarker seems to be a useful indicator before, during, and after cardiopulmonary bypass. Adrenomedullin seems to be useful in the pediatric population for a large variety of pathologies, especially regarding infection and cardiovascular conditions. However, it should be used in combination with other biomarkers and clinical or analytical variables, rather than as a single tool.

R, Patel PH, Bazan DZ, Mora A, Samuel N, Mingle AC, Leon LR, Varon J, Surani S. Drug-Induced Hyperthermia Review

Humans maintain core body temperature via a complicated system of physiologic mechanisms that counteract heat/cold fluctuations from metabolism, exertion, and the environment. Overextension of these mechanisms or disruption of body temperature homeostasis leads to bodily dysfunction, culminating in a syndrome analogous to exertional heat stroke (EHS). The inability of this thermoregulatory process to maintain the body temperature is caused by either thermal stress or certain drugs. EHS is a syndrome characterized by hyperthermia and the activation of systemic inflammation. Several drug-induced hyperthermic syndromes may resemble EHS and share common mechanisms. The purpose of this article is to review the current literature and compare exertional heat stroke (EHS) to three of the most widely studied drug-induced hyperthermic syndromes: malignant hyperthermia (MH), neuroleptic malignant syndrome (NMS), and serotonin syndrome (SS). Drugs and drug classes that have been implicated in these conditions include amphetamines, diuretics, cocaine, antipsychotics, metoclopramide, selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs), and many more. Observations suggest that severe or fulminant cases of drug-induced hyperthermia may evolve into an inflammatory syndrome best described as heat stroke. Their underlying mechanisms, symptoms, and treatment approaches will be reviewed to assist in accurate diagnosis, which will impact the management of potentially life-threatening complications.

Incidental diagnosis of medullary thyroid carcinoma due to persistently elevated procalcitonin in a patient with COVID-19 pneumonia: A case report

BACKGROUND

Procalcitonin (Pct) is a common biomarker in clinical practice, especially in the era of coronavirus disease 2019 (COVID-19) infection. Although it is frequently used for the diagnosis and prognostication of bacterial infections or sepsis, it is also elevated in a few other conditions, including medullary thyroid carcinoma (MTC).

CASE SUMMARY

A 43-year-old female presented with moderately severe COVID-19 pneumonia in April 2021. She gradually recovered clinically; however, despite normalization of other inflammatory markers, Pct levels remained persistently elevated. Further workup identified the cause as left lobe MTC with locoregional metastasis. Calcitonin levels were high, and carcinoembryonic antigen levels were normal. The patient underwent total thyroidectomy and neck dissection, which was followed by another radical neck dissection due to residual disease. Currently, she is doing well, nearly having completed her course of external beam radiotherapy with no recurrence. Pct is well documented as a screening tool for MTC, especially because of its stable nature compared to calcitonin in the community settings. It is important to keep in mind the differential diagnosis of MTC in patients with persistently elevated Pct levels despite normal levels of other acute phase reactants. To the best of our knowledge, this is the first report from Asia of such an incidental diagnosis of MTC due to persistently elevated Pct levels in a patient with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

CONCLUSION

Persistently elevated Pct levels can occur in any pro-inflammatory state including infections, sepsis, or acute respiratory distress syndrome. In the current setting, SARS-CoV-2 infection is one such clinical scenario, and in rare situations of persistent elevation, MTC may need to be ruled out.

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.

Procalcitonin as a diagnostic marker for infection in sickle cell disease

Background: Patients with sickle cell disease (SCD) are at increased risk of infection. Fever often occurs with vaso-occlusive crisis (VOC), posing a diagnostic challenge in SCD. Procalcitonin (PCT) is an infectious biomarker validated in the general population but with limited data on use in SCD.Methods: We performed a retrospective single-center study (n=145) with primary objective of assessing ability of PCT to differentiate infection from VOC in SCD presenting with fever. Subgroups included confirmed bacterial infection (CBI), suspected bacterial infection, viral infection and VOC. A secondary objective examined association of PCT with acute chest syndrome. Clinical characteristics and data were collected and analyzed to assess diagnostic performance of PCT and associated variables.Results: The majority of patients were male with HbSS genotype, age ranging 18-73 years and mean of 34 years. Of the cohort, 16% had CBI and 8% had viral infection. PCT was able to discriminate CBI from viral infection [AUC=0.89 (95%CI, 0.78-0.99)] and VOC [AUC=0.87 (95%CI, 0.78-0.97)]. PCT had association with ACS but poor diagnostic performance [AUC=0.69 (95% CI, 0.54-0.84)].Conclusion: PCT has utility in distinguishing confirmed bacterial infection from VOC or viral infection and is a promising biomarker when investigating fever in SCD.

Measurement of procalcitonin in saliva of pigs: a pilot study

Background

Procalcitonin (PCT) is a widely used biomarker of sepsis in human medicine and can have potential applications in the veterinary field. This study aimed to explore whether PCT could be measured in the saliva of pigs and whether its concentration changes in sepsis. Therefore, a specific assay was developed and analytically validated, and changes in PCT concentration were evaluated in two conditions: a) in an experimental model of sepsis produced by the administration of lipopolysaccharide (LPS) to pigs (n = 5), that was compared with a model of non-septic inflammation induced by turpentine oil (n = 4), and b) in healthy piglets (n = 11) compared to piglets with meningitis (n = 20), a disease that usually involves sepsis and whose treatment often requires large amounts of antibiotics in farms.

Results

The assay showed coefficients of variation within the recommended limits and adequate linearity after serial sample dilutions. The method's detection limit was set at 68 μg/L, and the lower limit of quantification was 414 μg/L. In the LPS experiment, higher concentrations of PCT were found after 24 h in the animals injected with LPS (mean = 5790 μg/L) compared to those treated with turpentine oil (mean = 2127 μg/L, P = 0.045). Also, animals with meningitis had higher concentrations of PCT (mean = 21515 μg/L) than healthy pigs (mean = 6096 μg/L, P value < 0.0001).

Conclusions

According to these results, this assay could be potentially used as a tool for the non-invasive detection of sepsis in pigs, which is currently a topic of high importance due to antibiotic use restriction.

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.