Procalcitonin to Detect Suspected Bacterial Infections in the PICU

The evolving value of older biomarkers in the clinical diagnosis of pediatric sepsis

Sepsis remains the leading cause of childhood mortality worldwide. The evolving definition of pediatric sepsis is extrapolated from adult studies. Although lacking formal validation in the pediatric population, this working definition has historically proven its clinical utility. Prompt identification of pediatric sepsis is challenging as clinical picture is often variable. Timely intervention is crucial for optimal outcome, thus biomarkers are utilized to aid in immediate, yet judicious, diagnosis of sepsis. Over time, their use in sepsis has expanded with discovery of newer biomarkers that include genomic bio-signatures. Despite recent scientific advances, there is no biomarker that can accurately diagnose sepsis. Furthermore, older biomarkers are readily available in most institutions while newer biomarkers are not. Hence, the latter's clinical value in pediatric sepsis remains theoretical. Albeit promising, scarce data on newer biomarkers have been extracted from research settings making their clinical value unclear. As interest in newer biomarkers continue to proliferate despite their ambiguous clinical use, the literature on older biomarkers in clinical settings continue to diminish. Thus, revisiting the evolving value of these earliest biomarkers in optimizing pediatric sepsis diagnosis is warranted. This review focuses on the four most readily available biomarkers to bedside clinicians in diagnosing pediatric sepsis. IMPACT: The definition of pediatric sepsis remains an extrapolation from adult studies. Older biomarkers that include C-reactive protein, procalcitonin, ferritin, and lactate are the most readily available biomarkers in most pediatric institutions to aid in the diagnosis of pediatric sepsis. Older biomarkers, although in varying levels of reliability, remain to be useful clinical adjuncts in the diagnosis of pediatric sepsis if used in the appropriate clinical context. C-reactive protein and procalcitonin are more sensitive and specific among these older biomarkers in diagnosing pediatric sepsis although evidence varies in different age groups and clinical scenarios.

Optimizing the Use of Antibiotic Agents in the Pediatric Intensive Care Unit: A Narrative Review

Antibiotics are one of the most prescribed drug classes in the pediatric intensive care unit, yet the incidence of inappropriate antibiotic prescribing remains high in critically ill children. Optimizing the use of antibiotics in this population is imperative to guarantee adequate treatment, avoid toxicity and the occurrence of antibiotic resistance, both on a patient level and on a population level. Antibiotic stewardship encompasses all initiatives to promote responsible antibiotic usage and the PICU represents a major target environment for antibiotic stewardship programs. This narrative review provides a summary of the available knowledge on the optimal selection, duration, dosage, and route of administration of antibiotic treatment in critically ill children. Overall, more scientific evidence on how to optimize antibiotic treatment is warranted in this population. We also give our personal expert opinion on research priorities.

Biomarkers in pediatric sepsis: a review of recent literature

Sepsis remains the leading cause of death in infants and children worldwide. Prompt diagnosis and monitoring of infection is pivotal to guide therapy and optimize outcomes. No single biomarker has so far been identified to accurately diagnose sepsis, monitor response and predict severity. We aimed to assess existing evidence of available sepsis biomarkers, and their utility in pediatric population. C-reactive protein and procalcitonin remain the most extensively evaluated and used biomarkers. However, biomarkers related to endothelial damage, vasodilation, oxidative stress, cytokines/chemokines and cell bioproducts have also been identified, often with regard to the site of infection and etiologic pathogen; still, with controversial utility. A multi-biomarker model driven by genomic tools could establish a personalized approach in future disease management.

The detection of bacterial infections in leukemia patients using procalcitionin levels

Bacteremic infections are the most common complications in patients with leukemia. This study aimed to assess the value of procalctionin levels in the detection of bacterial infections in leukemia patients. Blood samples of in-patients with leukemia were collected. Statistical analysis was performed to assess the correlation between the procalcitionin level on the day of the first positive blood culture and bacteremic infection. Infected patients had significantly higher procalctionin levels than uninfected patients (p < 0.001). Receiver operating characteristic curve analysis showed a high level of accuracy regarding the discrimination of bacterarmic infection (area under the curve, 0.883) and Gram-negative bateremia (area under the curve, 0.779). Procalctionin levels may help in the identification of bacterial infections in leukemia patients. Further multicentre studies are needed to verify our data regarding the use of procalctionin to distinguish between Gram-positive and Gram-negative infections.

Association of Procalcitonin Value and Bacterial Coinfections in Pediatric Patients With Viral Lower Respiratory Tract Infections Admitted to the Pediatric Intensive Care Unit

OBJECTIVE

Our primary objective was to determine the utility of procalcitonin (PCT) in detection of bacterial coinfection in children < 5 years admitted to the pediatric intensive care unit with viral lower respiratory tract infection (LRTI).

METHODS

Electronic medical record review of children < 5 years admitted to the pediatric intensive care unit with a viral LRTI who also had at least 1 PCT concentration measurement.

RESULTS

Seventy-five patients were admitted to the intensive care unit and met the inclusion criteria for this investigation. The PCT threshold concentrations of 0.9, 1, 1.4, and 2 ng/mL were found to be statistically significant in determining the presence of a bacterial coinfection. The PCT concentration with the most utility was 1.4 ng/mL with sensitivity, specificity, positive and negative predictive values of 46%, 83%, 68%, and 76%, respectively. For patients with serial PCTs, the second PCT correctly influenced treatment decisions for 11 of 25 patients (44%).

CONCLUSIONS

A PCT value of 1.4 ng/mL determined the presence of a bacterial coinfection primarily owing to the high specificity and negative predictive value. Our data add evidence to the relatively high negative predictive value of PCT concentrations in identifying patients with bacterial coinfection, specifically in the case of viral LRTI. In addition, our preliminary data indicate serial PCT measurements may help further influence correct treatment decisions. Prospective, controlled studies are warranted to validate an appropriate PCT threshold concentration to help in identifying bacterial coinfection as well as to further explore the role of serial PCT values in determining the absence or presence of a bacterial coinfection.

Procalcitonin to Detect Bacterial Infections in Critically Ill Pediatric Patients

The diagnostic power of procalcitonin (PCT) in the pediatric intensive care unit (PICU) is uncertain. This study aimed to determine the diagnostic ability of PCT to detect serious bacterial infections (SBI) in a heterogeneous PICU population. This was a retrospective cohort study of patients on whom a PCT level was obtained within 48 hours of admission to a PICU from 2013 to 2015. Discriminatory ability of PCT to predict SBI was examined by test and receiver operating characteristics (AUC [area under the curve]-ROC). Seventy-five patients were included and 28 (37%) had an SBI (median PCT = 6.48 ng/mL) compared with 47 (63%) in the noninfection group (median PCT = 0.23 ng/mL, P < .0001). PCT was able to adequately predict SBI (AUC-ROC = 0.83, 95% CI 0.74-0.93; P < .0001), and a PCT ≥1.28 ng/mL was the optimal threshold to detect SBI with a positive predictive value of 76.7% and negative predictive value of 88.9%. PCT adequately predicted SBI in a heterogeneous PICU population and may be useful for minimizing antibiotic consumption.

Diagnostic Accuracy of a Host Gene Expression Signature That Discriminates Clinical Severe Sepsis Syndrome and Infection-Negative Systemic Inflammation Among Critically Ill Children

OBJECTIVES

SeptiCyte Lab (Immunexpress, Seattle, WA), a molecular signature measuring the relative expression levels of four host messenger RNAs, was developed to discriminate critically ill adults with infection-positive versus infection-negative systemic inflammation. The objective was to assess the performance of Septicyte Lab in critically ill pediatric patients.

DESIGN

Prospective observational study.

SETTING

Pediatric and Cardiac ICUs, Seattle Children's Hospital, Seattle, WA.

PATIENTS

A cohort of 40 children with clinically overt severe sepsis syndrome and 30 children immediately postcardiopulmonary bypass surgery was recruited. The clinically overt severe sepsis syndrome children had confirmed or highly suspected infection (microbial culture orders, antimicrobial prescription), two or more systemic inflammatory response syndrome criteria (including temperature and leukocyte criteria), and at least cardiovascular ± pulmonary organ dysfunction.

INTERVENTIONS

None (observational study only).

MEASUREMENTS AND MAIN RESULTS

Next-generation RNA sequencing was conducted on PAXgene blood RNA samples, successfully for 35 of 40 (87.5%) of the clinically overt severe sepsis syndrome patients and 29 of 30 (96.7%) of the postcardiopulmonary bypass patients. Forty patient samples (~ 60% of cohort) were reanalyzed by reverse transcription-quantitative polymerase chain reaction, to check for concordance with next-generation sequencing results. Postcardiopulmonary bypass versus clinically overt severe sepsis syndrome descriptors included the following: age, 7.3 ± 5.5 versus 9.0 ± 6.6 years; gender, 41% versus 49% male; Pediatric Risk of Mortality, version III, 7.0 ± 4.6 versus 8.7 ± 6.4; Pediatric Logistic Organ Dysfunction, version II, 5.1 ± 2.2 versus 4.8 ± 2.8. SeptiCyte Lab strongly differentiated postcardiopulmonary bypass and clinically overt severe sepsis syndrome patients by receiver operating characteristic curve analysis, with an area-under-curve value of 0.99 (95% CI, 0.96-1.00). Equivalent performance was found using reverse transcription-quantitative polymerase chain reaction. There was no significant correlation between the score produced by the SeptiCyte Lab test and measures of illness severity, immune compromise, or microbial culture status.

CONCLUSIONS

SeptiCyte Lab is able to discriminate clearly between clinically well-defined and homogeneous postcardiopulmonary bypass and clinically overt severe sepsis syndrome groups in children. A broader investigation among children with more heterogeneous inflammation-associated diagnoses and care settings is warranted.

Procalcitonin for infections in the first week after pediatric liver transplantation

Background

Procalcitonin (PCT) has become a commonly used serum inflammatory marker. Our aim was to describe the kinetics and usefulness of serial post-operative PCT measurements to detect bacterial infection in a cohort of children immediately after pediatric liver transplantation (pLT).

Methods

We performed a retrospective chart review of a cohort of pLT recipients with serial serum PCT measurements in the first week following pLT. The presence of infection was determined on clinical and biological parameters. Normal PCT was defined as < 0.5 (ng/ml).

Results

Thirty-nine patients underwent 41 pLT. PCT was measured daily during the first week post pLT. Values first increased following surgery and then decreased, nearing 0.5 ng/ml at day seven. Peak PCT reached a median of 5.61 ng/ml (IQR 3.83-10.8). Seventeen patients were considered to have an infection. There was no significant difference in daily PCT or peak PCT between infected and non infected patients during the first post-operative week. AUC of ROC curve for PCT during first week was never higher than 0.6.

Conclusions

We conclude that serial PCT measurements during the first week after pLT is not useful to identify patients with bacterial infections. Rather, we propose that serum PCT may be useful after the first week post pLT.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2234-y) contains supplementary material, which is available to authorized users.

Value of Procalcitonin Measurement for Early Evidence of Severe Bacterial Infections in the Pediatric Intensive Care Unit

OBJECTIVES

To determine whether peak blood procalcitonin (PCT) measured within 48 hours of pediatric intensive care unit (PICU) admission can differentiate severe bacterial infections from sterile inflammation and viral infection and identify potential subgroups of PICU patients for whom PCT may not have clinical utility.

STUDY DESIGN

This was a retrospective, observational study of 646 critically ill children who had PCT measured within 48 hours of admission to an urban, academic PICU. Patients were stratified into 6 categories by infection status. We compared test characteristics for peak PCT, C-reactive protein (CRP), white blood cell count (WBC), absolute neutrophil count (ANC), and % immature neutrophils. The area under the receiver operating characteristic curve was determined for each biomarker to discriminate bacterial infection.

RESULTS

The area under the receiver operating characteristic curve was similar for PCT (0.73, 95% CI 0.69, 0.77) and CRP (0.75, 95% CI 0.71, 0.79; P = .36), but both outperformed WBC, ANC, and % immature neutrophils (P < .01 for all pairwise comparisons). The combination of PCT and CRP was no better than either PCT or CRP alone. Diagnostic patterns prone to false-positive and false-negative PCT values were identified.

CONCLUSIONS

Peak blood PCT measured close to PICU admission was not superior to CRP in differentiating severe bacterial infection from viral illness and sterile inflammation; both PCT and CRP outperformed WBC, ANC, and % immature neutrophils. PCT appeared especially prone to inaccuracies in detecting localized bacterial central nervous system infections or bacterial coinfection in acute viral illness causing respiratory failure.

Procalcitonin Is a Better Biomarker than C-Reactive Protein in Newborns Undergoing Cardiac Surgery: The PROKINECA Study

OBJECTIVES

To assess the kinetics of procalcitonin (PCT) and C-reactive protein (CRP) in newborns after cardiothoracic surgery (CS), with and without cardiopulmonary bypass, and to assess whether PCT was better than CRP in identifying sepsis in the first 72 hours after CS.

PATIENTS AND METHODS

This is a prospective study of newborns admitted to the neonatal intensive care unit after CS.

INTERVENTIONS

PCT and CRP were sequentially drawn 2 hours before surgery and at 0, 12, 24, 48, and 72 hours after surgery.

RESULTS

A total of 65 patients were recruited, of which 14 were excluded because of complications. We compared the kinetics of PCT and CRP after CS in bypass and non-bypass groups without sepsis; there were no differences in the PCT values at any time (24 hours, P = 0.564; 48 hours, P = 0.117; 72 hours, P = 0.076). Thirty-five patients needed bypass, of whom four were septic (11.4%). Significant differences were detected in the PCT values on comparing the septic group to the nonseptic group at 48 hours after cardiopulmonary bypass (P = 0.018). No differences were detected in the CRP values in these groups. A suitable cutoff for sepsis diagnosis at 48 hours following bypass would be 5 ng/mL, with optimal area under the curve of 0.867 (confidence interval 0.709–0.958), P < 0.0001, and sensitivity and specificity of 87.5% (29.6–99.7) and 72.6% (53.5–86.4), respectively.

CONCLUSION

This is a preliminary study but PCT seems to be a good biomarker in newborns after CS. Values over 5 ng/mL at 48 hours after CS should alert physicians to the high risk of sepsis in these patients.

The Diagnostic Accuracy of Serum Procalcitonin for Bacteremia in Critically Ill Children

BACKGROUND

Bacterial sepsis is frequently encountered in children admitted to the Pediatric Intensive Care Unit (PICU) and requires early recognition and treatment. Procalcitonin (PCT) is a serum biomarker with a high sensitivity to predict bacteremia in critically-ill adults. This study sought to evaluate the diagnostic accuracy of PCT for bacteremia in febrile children in the PICU.

METHODS

This retrospective observational study used data from children admitted to the PICU from October 2010 to October 2012. Patients up to 21 years of age were included if they had an abnormal temperature, serum PCT and blood culture assayed, and were not receiving empiric antibiotics at the time.

RESULTS

There were 202 PCT values that met inclusion criteria. The prevalence of positive blood cultures was 13.2% (27 total positive blood cultures). The area under the curve (AUC) for PCT was 0.79 (95% CI, 0.70-0.89), the AUC for lactate was 0.76 (95% CI, 0.65-0.87), and the AUC for C-reactive protein was 0.68 (95% CI, 0.57-0.80). The optimal threshold of PCT for accuracy was determined to be 2 ng/mL (sensitivity = 69.2%, specificity = 74.4%, positive predictive value = 28.6%, negative predictive value = 94.2%). The combination of an abnormal lactate (> 2.0mmol/L) increased the specificity of PCT for diagnosing bacteremia.

CONCLUSIONS

PCT has a good diagnostic accuracy to rule-out bacteremia in critically-ill, febrile children. The combination of PCT and an abnormal lactate value increases the specificity and may improve the ability to diagnose bacteremia.