Procalcitonin and C-reactive protein serum levels as markers of infection in a pediatric population with febrile neutropenia and cancer

The Applicability of a 2-Transcript Signature to Identify Bacterial Infections in Children with Febrile Neutropenia

Febrile neutropenia is a common complication during chemotherapy in paediatric cancer care. In this setting, clinical features and current diagnostic tests do not reliably distinguish between bacterial and viral infections. Children with cancer (n = 63) presenting with fever and neutropenia were recruited for extensive microbiological and blood RNA sampling. RNA sequencing was successful in 43 cases of febrile neutropenia. These were classified as having probable bacterial infection (n = 17), probable viral infection (n = 13) and fever of unknown origin (n = 13) based on microbiological defined infections and CRP cut-off levels. RNA expression data with focus on the 2-transcript signature (FAM89A and IFI44L), earlier shown to identify bacterial infections with high specificity and sensitivity, was implemented as a disease risk score. The median disease risk score was higher in the probable bacterial infection group, -0.695 (max 2.795; min -5.478) compared to the probable viral infection group -3.327 (max 0.218; min -7.861), which in ROC analysis corresponded to a sensitivity of 0.88 and specificity of 0.54 with an AUC of 0.80. To further characterise the immune signature, analysis of significantly expressed genes and pathways was performed and upregulation of genes associated to antibacterial responses was present in the group classified as probable bacterial infection. Our results suggest that the 2-transcript signature may have a potential use as a diagnostic tool to identify bacterial infections in immunosuppressed children with febrile neutropenia.

Biomarkers for Diagnosing Febrile Illness in Immunocompromised Children: A Systematic Review of the Literature

OBJECTIVE

This study aims to assess the performance of biomarkers used for the prediction of bacterial, viral, and fungal infection in immunocompromised children upon presentation with fever.

METHODS

We performed a literature search using PubMed and MEDLINE and In-Process & Other Non-indexed Citations databases. Cohort and case-control studies assessing biomarkers for the prediction of bacterial, viral, or fungal infection in immunocompromised children vs. conventional microbiological investigations were eligible. Studies including adult patients were eligible if pediatric data were separately assessable. Data on definitions used for infections, fever, and neutropenia and predictive values were collected. Risk of bias was assessed with the Quality Assessment of Diagnostic Accuracy Studies-2 tool.

RESULTS

Fifty-two studies involving 13,939 febrile episodes in 7,059 children were included. In total, 92.2% were in cancer patients (n = 48), and 15.7% also included hematopoietic stem cell transplantation patients (n = 8). Forty-three biomarkers were investigated, of which 6 (CRP, PCT, IL-8, IL-6, IL-10, and TNFα) were significantly associated with bacterial infection at admission, studied in multiple studies, and provided predictive data. Literature on the prediction of viral and fungal infection was too limited. Eight studies compared C-reactive protein (CRP) and procalcitonin (PCT), with PCT demonstrating superiority in 5. IL-6, IL-8, and IL-10 were compared with CRP in six, four, and one study, respectively, with mixed results on diagnostic superiority. No clear superior biomarker comparing PCT vs. IL-6, IL-8, or IL-10 was identified.

DISCUSSION

There is great heterogeneity in the biomarkers studied and cutoff values and definitions used, thus complicating the analysis. Literature for immunocompromised children with non-malignant disease and for non-bacterial infection is sparse. Literature on novel diagnostics was not available. We illustrated the challenges of diagnosing fever adequately in this study population and the need for improved biomarkers and clinical decision-making tools.

Predictive value of PCT and IL-6 for bacterial infection in children with cancer and febrile neutropenia

Purpose

Only a third of children with cancer and febrile neutropenia (FN) have a proven bacterial infection; nevertheless, most children are hospitalized and treated with intravenous antibiotics. Several biomarkers have been proposed as predictive markers for bacterial infection in this population. We aimed to evaluate the role of interleukin-6 (IL-6) and procalcitonin (PCT) in diagnosing bacterial infection in children with cancer and FN.

Methods

The study population was derived from a prospective database (2006–2013, IL-8 study) comprising children with cancer who presented with FN. From stored plasma samples (taken at admission and/or at 12–24 h), we determined the PCT and IL-6 levels. Consequently, we explored their relation with the presence of bacterial infection (positive blood culture, radiologically documented infection or clinical bacterial focus). We predefined cutoff values at 60 ng/L for IL-6 and 0.25 ng/mL for PCT.

Results

Seventy-seven FN episodes in 55 children with cancer were included. In 18 episodes (23.4%), a bacterial infection was documented. Both at presentation and after 12–24 h, median values of IL-6 and PCT were significantly higher in patients with a bacterial infection compared to patients without a bacterial infection. With both biomarkers above cutoff values, sensitivity was 93% (with either one, this was even 100%). The identified group at low risk for bacterial infection comprised 41% of the population.

Conclusion

PCT and IL-6 are promising markers in identifying bacterial infection in children with cancer and FN. In a subsequent project, we will incorporate these biomarkers in a risk assessment model that we will test prospectively in a clinical trial.

Procalcitonin: The marker of pediatric bacterial infection

Timely recognition of systemic bacterial infections in pediatric care setting is the basis for effective treatment and control. This review provides an overview of procalcitonin (PCT) as an early marker for the detection of severe, invasive bacterial infection in children. Almost all articles on biochemical property and clinical studies in PubMed and Scopus databases regarding their use in pediatric infections and the use of PCT as a marker of bacterial infections were examined. Various methods and analyzers are currently available for the evaluation of PCT. Employment of PCT in the identification of neonatal bacterial infection is a complex process in some conditions. Age specific cut-off, underlying syndrome, and maternal antibiotics usage should be considered when PCT is to be applied in neonates. PCT might be false-negative in these conditions. However, if used appropriately, it can lead to a higher specificity than other immunologic markers. Due to its correlation with the severity of infection, PCT can consequently be used as a prognostic indicator especially for sepsis and urinary tract infection. It is, therefore, a practical supplementary means for the identification of bacterial infections in pediatric health settings.

Febrile neutropenia in children treated for malignancy

Febrile neutropenia (FN) in children treated for malignancy is a common and direct sequela of chemotherapy. Episodes of FN can be life-threatening, and demand prompt recognition, assessment and treatment with broad spectrum antibiotics. While in the majority of episodes no causal infection is identified, 10-20% are secondary to a bloodstream infection (BSI). A reduction in episodes of BSI could be achieved through robust infection prevention strategies, such as CVL care bundles. Alongside good antimicrobial stewardship, these strategies could reduce the risk of emergent, multi-drug resistant (MDR) infections. Emerging bacterial pathogens in BSI include Viridans Group Streptococci (VGS) and Enterobacteriaceae such as Klebsiella spp. which are known for their ability to carry MDR genes. There is also increased recognition of the role of invasive fungal infection (IFI) in FN, in particular with Aspergillus spp. Novel diagnostics, including multiplex blood and respiratory polymerase chain reaction assays can identify infections early in FN, facilitating targeted therapy, and reducing unnecessary antimicrobial exposure. Given appropriate, and sensitive rapid diagnostics, potential also exists to safely inform the risk assessment of patients with FN, identifying those at low risk of complication, who could be treated in the out-patient setting. Several clinical decision rules (CDR) have now been developed and validated in defined populations, for the risk assessment of children being treated for cancer. Future research is needed to develop a universal CDR to improve the management of children with FN.

Does procalcitonin, C-reactive protein, or interleukin-6 test have a role in the diagnosis of severe infection in patients with febrile neutropenia? A systematic review and meta-analysis

PURPOSE

The study aims to determine the usefulness of procalcitonin (PCT) and other blood markers for identification of bacterial infection among patients with febrile neutropenia (FN).

METHODS

The Medline, EMBASE, and Cochrane databases were searched for articles from 1966 to December 2012. We performed a search to identify articles that examined the diagnostic accuracy of PCT in patients with FN. Statistical analyses (fixed- or random-effect models) were conducted to summarize and calculate the sensitivity, specificity, likelihood ratios, and 95 % confidence intervals (CIs).

RESULTS

Twenty-seven studies were included (1960 febrile episodes) for PCT analysis, 13 (1712 febrile episodes) for C-reactive protein (CRP) analysis, and five (314 febrile episodes) for interleukin (IL)-6 analysis. Increased PCT levels (odds ratio [OR] 11.5; 95 % CI 7.6 to 17.3), raised CRP levels (3.3; 2.7 to 4.2), and raised IL-6 levels (10.0; 5.5 to 18.0) were significantly associated with bacterial infection. Overall positive likelihood ratio was 5.49 (4.04-7.45) for PCT, 1.82 (1.42-2.33) for CRP, and 3.68 (2.41-5.60) for IL-6. Overall negative likelihood ratio was 0.40 (0.31-0.51) for PCT, 0.40 (0.26-0.61) for CRP, and 0.33 (0.23-0.46) for IL-6.

CONCLUSIONS

Of the three potentially useful markers, PCT had the best positive likelihood ratio and can be used to confirm the diagnosis of bacterial infections in patients with FN. Due to unacceptably high negative likelihood ratio, medical decision for stopping antibiotics based on PCT alone in this high-risk population may not be possible.

Serial procalcitonin levels to detect bacteremia in febrile neutropenia

BACKGROUND

Our objective was to evaluate serial procalcitonin (PCT) levels compared with an initial PCT level at admission in predicting bacteremia in pediatric febrile neutropenic oncology patients.

PROCEDURE

Serum PCT levels were measured at admission (t0) and within 24 hours of admission (t1) in pediatric oncology patients presenting with fever and neutropenia. A blood culture was collected at t0 and monitored for 5 days for bacterial growth. PCT value of 0.5 ng/mL at either t0 or t1 was considered predictive for bacteremia.

RESULTS

PCT levels were significantly higher in children with positive blood cultures than with negative blood cultures. Serial PCT values mirrored t1 values. Serial PCT showed 76% specificity and negative predictive value of 93% in ruling out bacteremia.

CONCLUSION

Elevated PCT levels are predictive of bacteremia. Using serial PCT levels within 24 hours allowed a better prediction of bacteremia than the PCT level at t0.

Procalcitonin as a marker of bacteremia in children with fever and a central venous catheter presenting to the emergency department

OBJECTIVE

To evaluate the clinical use of procalcitonin (PCT) as a rapid marker for the identification of bacteremia in the emergency department (ED) population of children with fever and a central venous catheter (CVC).

METHODS

Children were identified on presentation to the ED with a chief complaint of fever and who had a CVC. Fever was defined as 38°C or higher orally. Patients were excluded from the study if they had received antibiotics within the previous 24 hours of presenting to the ED, if they had a peripherally inserted central catheter line or by parental refusal. On presentation to the ED, all patients had a complete blood cell count with differential, blood culture from the central line, and PCT levels drawn. All had empiric antibiotics initiated. Blood culture results were recorded, and in the case of positive cultures, time to positive culture was noted.

RESULTS

Sixty-two patients (aged 5 months-18 y) were enrolled, and 14 (23%) had a positive culture. Mean PCT value in bacteremic patients was 18.47 ± 31.6 ng/mL and 0.65 ± 1.2 ng/mL in nonbacteremic patients (P < 0.001). Median PCT for negative blood culture was 0.23 ng/mL (interquartile range, 0.11-0.61) and 1.15 ng/mL for a positive blood culture (interquartile range, 0.45-29.16). The receiver operating characteristic analysis identified a level of PCT of 0.3 ng/mL as the best cutoff point that produced a sensitivity of 93% and a specificity of 63% (area under the curve, 0.82).

CONCLUSIONS

The PCT levels are useful in identifying children with fever and a CVC who are bacteremic in the ED.

Role of procalcitonin in the diagnosis of severe infection in pediatric patients with fever and Neutropenia--a systemic review and meta-analysis

OBJECTIVE

The aim of this study was to determine the accuracy of the procalcitonin (PCT) test for diagnosis of bacterial sepsis in pediatric cancer patients with febrile neutropenia.

METHODS

Three major databases, MEDLINE, EMBASE and the Cochrane Library were searched for studies that evaluated the diagnostic value of PCT alone or compared with other laboratory markers such as C-reactive protein (CRP) to identify bacterial sepsis in children with fever and neutropenia. A bivariate model was used to derive summary sensitivity and specificity of the diagnostic tests.

RESULTS

A total of 10 studies looking into PCT tests and 8 studies looking into CRP tests were included in the final analysis. The prevalence of bacterial sepsis was 304 of 1031 (29.5%) in PCT studies and 741 of 1316 (56.3%) in CRP studies. In terms of area under the receiver operating characteristic curve, PCT had comparable discrimination to CRP (area under the curve: 0.75 versus 0.74). PCT was not as sensitive as the CRP test. The pooled sensitivity of PCT was 0.59 (95% confidence interval [CI]: 0.42-0.74) as compared with 0.75 (95% CI: 0.61-0.85) for CRP. PCT was more specific than sensitive whereas CRP was more sensitive than specific in this population. The pooled specificity was 0.76 (95% CI: 0.64-0.85) for PCT and 0.62 (95% CI: 0.49-0.73) for CRP. PCT had greater likelihood ratio positive (2.50; 95% CI: 1.64-3.81), making it the better rule-in test.

CONCLUSIONS

Of three markers potentially useful for diagnosing bacterial sepsis in children with fever and neutropenia, PCT had comparable diagnostic accuracy to CRP.

New molecular and surrogate biomarker-based tests in the diagnosis of bacterial and fungal infection in febrile neutropenic patients

PURPOSE OF REVIEW

Prompt diagnosis of infection in febrile neutropenia hosts with hematological malignancy is essential in directing therapy. We highlight experience using modern molecular and biomarker-based methods to diagnose bacterial and fungal bloodstream infections and invasive aspergillosis in these patients.

RECENT FINDINGS

Nucleic acid amplification-based strategies are used to detect and identify pathogens from blood cultures or from blood/clinical specimens; the latter are more likely to influence clinical management. Advances in DNA extraction include standardization of isolation of Aspergillus DNA from blood. Broad-range and/or multiplex PCR generally have greater clinical utility than pathogen-specific assays. However, Aspergillus-PCR assays are useful in confirming/excluding disease and monitoring high-risk patients for invasive aspergillosis. Commercial real-time PCR/peptide nucleic acid fluorescent in-situ hybridization systems, used as adjuncts to blood cultures, to detect bacteria and fungi in blood cultures (or blood), are as sensitive as culture and enable earlier institution of targeted therapy. Yet there are no data indicating that molecular detection of bacterial/fungal pathogens influences patient outcomes. Positive serum Aspergillus galactomannan and 1,3-β-D-glucan tests are useful biomarkers in the diagnosis/screening of fungal infection, and have potential as measures of response to antifungal therapy. Serum procalcitonin levels can help differentiate infectious, from noninfectious, fever. Combined molecular and nonmolecular testing likely offers optimal diagnostic accuracy.

SUMMARY

Numerous PCR-based and biomarker tools are available for the diagnosis and screening of infection in febrile neutropenia hosts. The optimal approach remains to be resolved by prospective studies examining the impact of one or more of tests on patient outcomes.

Predicting the risk of severe bacterial infection in children with chemotherapy-induced febrile neutropenia

BACKGROUND

The prognosis of febrile neutropenia (FN) in childhood cancer has been considerably improved by the intensification of treatment, including systematic hospitalization and broad-spectrum antibiotics. As only few children present with a severe bacterial infection (SBI), clinical decision rules have been developed to distinguish those at risk for SBI. The aim of this study was to evaluate the reproducibility of six clinical decision rules proposed in the literature and to compare their performance.

METHODS

This retrospective two-center cohort study included all episodes of chemotherapy-induced FN in children admitted between January 2005 and December 2006. Each rule was applied to our patients. Their sensitivity (Se) and specificity (Sp) were calculated and compared with the authors' results, to assess reproducibility. The most predictive rule was defined in advance as that yielding 100% Se, the highest Sp, and the greatest simplicity for bedside application.

RESULTS

Three hundred seventy-seven episodes of FN in 167 patients were collected; 64 episodes were associated with SBI, including 36 with bacteremia. Four of the six rules were reproducible, but none were able to be validated. The most predictive rule for bacteremia had 96% Se (95% confidence interval (CI): 79-99%) and 25% Sp (95% CI: 19-33%), and the most predictive rule for SBI had 95% Se (95% CI: 87-98%), but no power of discrimination (Sp = 5%, 95% CI: 3-8%).

CONCLUSION

This study emphasizes the difficulty in identifying standardized decision rules in the management of a condition with numerous clinical variables like FN.

Supportive care in children

PURPOSE OF REVIEW

To provide an update on the rational approach of febrile neutropenia in children with cancer and discuss future research aspects in the field.

RECENT FINDINGS

Clinical and laboratory variables and new biomarkers associated with an increased risk for a severe outcome including invasive bacterial infection (IBI), sepsis, and mortality have been identified for children with cancer and febrile neutropenia. These variables and biomarkers are currently being used for an early risk assessment in order to identify children at low or high risk for IBI or at high risk for sepsis and death. Early identification of children with a differential risk has allowed the implementation of selective treatment regimens. More recently, host genetic differences have been associated with a differential risk for IBI. The individual gene profile based on selected polymorphisms could further fine-tune the early risk assessment allowing tailor-made management strategies.

SUMMARY

In the last decades, efforts have focused on the stratification of the heterogeneous group of children with cancer and febrile neutropenia according to their risk for developing an IBI. This effort has allowed a less aggressive treatment strategy for children at low risk, including early hospital discharge and use of intravenous and oral antimicrobials at home. More recently, advances have been made in the early identification of children in the other spectrum of infection, those at high risk for sepsis and mortality, with the aim of rapid implementation of aggressive therapy.