Procalcitonin as a marker of severe bacterial infection in children in the emergency department

Clinical Predictors and Biomarkers in Children With Sepsis and Bacterial Meningitis

OBJECTIVES

Sepsis and meningitis in children may present with different clinical features and a wide range of values of inflammatory markers. The aim of this study was to identify the prognostic value of clinical features and biomarkers in children with sepsis and bacterial meningitis in the emergency department (ED).

METHODS

We carried out a single-center, retrospective, observational study on 194 children aged 0 to 14 years with sepsis and bacterial meningitis admitted to the pediatric ED of a tertiary children's hospital through 12 years.

RESULTS

Among epidemiological and early clinical features, age older than 12 months, capillary refill time greater than 3 seconds, and oxygen blood saturation lower than 90% were significantly associated with unfavorable outcomes, along with neurological signs ( P < 0.05). Among laboratory tests, only procalcitonin was an accurate and early prognostic biomarker for sepsis and bacterial meningitis in the ED, both on admission and after 24 hours. Procalcitonin cut-off value on admission for short-term complications was 19.6 ng/mL, whereas the cut-off values for long-term sequelae were 19.6 ng/mL on admission and 41.9 ng/mL after 24 hours, respectively. The cut-off values for mortality were 18.9 ng/mL on admission and 62.4 ng/mL at 24 hours.

CONCLUSIONS

Procalcitonin, along with clinical evaluation, can guide the identification of children at higher risk of morbidity and mortality, allowing the most appropriate monitoring and treatment.

Late-onset Group B Streptococcus Bacteremia Evaluated in the Pediatric Emergency Department and Risk Factors for Severe Infection

BACKGROUND

To describe the infants presenting to pediatric emergency departments (PEDs) and diagnosed with group B Streptococcus (GBS) late-onset disease (LOD) bacteremia and identify risk factors for severe infection and pediatric intensive care unit (PICU) admission.

METHODS

Observational study and subanalysis of a multicenter prospective registry. Setting: pediatric emergency department. Inclusion criteria: infants between 7 and 89 days of age with positive blood culture for GBS seen between 2011 and 2016 at any of 22 Spanish PEDs. Main outcome: risk factors (clinical and laboratory variables) for severe infection (sepsis/septic shock or meningitis) and PICU admission. Second, the prevalence of poor outcomes (acute complications, sequelae or death).

RESULTS

Among 118 patients with LOD, 74 (62.7%) presented a severe infection: 66 sepsis/septic shock (11 with associated meningitis) and 8 meningitis. Thirty-five patients (29.7%) were admitted to a PICU. An altered Pediatric Assessment Triangle (PAT) upon arrival and leukopenia were the only independent risk factors for severe infection [odds ratio (OR): 43.6; 95% confidence interval (CI): 8.1-235.7, P < 0.01] and PICU admission (OR: 11.6; 95% CI: 1.5-91.4; P < 0.019), respectively. Six patients (5.1%) developed a poor outcome, including 2 deaths (1.7%); all had an altered PAT, elevated procalcitonin (range 4.7-100 ng/ml), and were diagnosed with sepsis/septic shock and admitted to a PICU. Four developed leukopenia.

CONCLUSIONS

Infants with GBS LOD frequently develop sepsis/septic shock and bacterial meningitis, associated with non-negligible morbidity and mortality. Clinical appearance was the only risk factor for severe infection, whereas leukopenia was related to PICU admission.

Thymoquinone modulates the expression of sepsis‑related microRNAs in a CLP model

Sepsis is a clinical syndrome common in critical care settings. In the present study, the therapeutic effect of thymoquinone (TQ) on the expression of sepsis-related microRNAs (miRNAs/miRs), levels of inflammatory markers, organ dysfunction and mortality were investigated in a cecal ligation and puncture (CLP) rat model. A single dose of TQ (1 mg/kg) was administered to animals 24 h after CLP and the mortality rate was assessed up to 7 days following the induction of sepsis. In addition, blood samples were collected at different time points and the expression levels of miRNAs (i.e. miR-16, miR-21, miR-27a and miR-34a) were examined, along with the levels of inflammatory cytokines (i.e. TNF-α, IL-1α, IL-2, IL-6 and IL-10) and sepsis markers (i.e. C-reactive protein, endothelial cell-specific molecule-1, VEGF, procalcitonin and D-dimer). Liver, kidney and lung tissues were also collected for further histological examination. Treatment with TQ significantly downregulated the miRNA expression levels, as well as the levels of inflammatory cytokines and early-stage sepsis biomarkers by 30-70% at 12-36 h (P<0.05). Furthermore, CLP model rats treated with TQ exhibited an ~80% increase in survival rate compared with that in the untreated CLP group. In addition, TQ induced the preservation of organ function and structure. In conclusion, the present study demonstrated a promising therapeutic effect of TQ against the sequelae of sepsis.

Pattern of inflammatory immune response determines the clinical course and outcome of COVID-19: unbiased clustering analysis

The objective of the study was to identify distinct patterns in inflammatory immune responses of COVID-19 patients and to investigate their association with clinical course and outcome. Data from hospitalized COVID-19 patients were retrieved from electronic medical record. Supervised k-means clustering of serial C-reactive protein levels (CRP), absolute neutrophil counts (ANC), and absolute lymphocyte counts (ALC) was used to assign immune responses to one of three groups. Then, relationships between patterns of inflammatory responses and clinical course and outcome of COVID-19 were assessed in a discovery and validation cohort. Unbiased clustering analysis grouped 105 patients of a discovery cohort into three distinct clusters. Cluster 1 (hyper-inflammatory immune response) was characterized by high CRP levels, high ANC, and low ALC, whereas Cluster 3 (hypo-inflammatory immune response) was associated with low CRP levels and normal ANC and ALC. Cluster 2 showed an intermediate pattern. All patients in Cluster 1 required oxygen support whilst 61% patients in Cluster 2 and no patient in Cluster 3 required supplementary oxygen. Two (13.3%) patients in Cluster 1 died, whereas no patient in Clusters 2 and 3 died. The results were confirmed in an independent validation cohort of 116 patients. We identified three different patterns of inflammatory immune response to COVID-19. Hyper-inflammatory immune responses with elevated CRP, neutrophilia, and lymphopenia are associated with a severe disease and a worse outcome. Therefore, targeting the hyper-inflammatory response might improve the clinical outcome of COVID-19.

Procalcitonin and D-dimer for Predicting 28-Day-Mortality Rate and Sepsis Severity based on SOFA Score; A Cross-sectional Study

Objective:

To determine the possible relationship of procalcitonin (PCT) and D-dimer with the 28-day-mortality rate and severity of sepsis based on sequential organ failure assessment (SOFA) score.

Methods:

In this cross-sectional study, patients were enrolled based on their signs and symptoms of sepsis confirmed by essential laboratory studies. Demographic data, Glasgow coma scale and vital signs, serum PCT and D-dimer levels, creatinine, bilirubin level, arterial blood gas analysis and platelet count were recorded. Disease severity index was assessed based on SOFA score. Patients’ 28-day-mortality rate and hospital length of stay were compared with the study variables.

Results:

Sixty-four patients with the mean age of 78.3±11.6 were included of whom 34 cases (53.1%) were male. The 28-day-mortality rate was 17%. The analysis showed that only patients’ age (p=0.01) and platelet count (p=0.02) had a statistically significant association with the mortality rate. SOFA score had no statistically significant correlation with PCT or D-dimer; and these two markers didn’t have any significant correlation in terms of predicting mortality due to the sepsis.

Conclusion:

In our study, PCT and D-dimer failed to show any significant correlation with 28-day-mortality rate of sepsis.

Acute phase reactant serum amyloid A in inflammation and other diseases

Acute-phase reactant serum amyloid A (A-SAA) plays an important role in acute and chronic inflammation and is used in clinical laboratories as an indicator of inflammation. Although both A-SAA and C-reactive protein (CRP) are acute-phase proteins, the detection of A-SAA is more conclusive than the detection of CRP in patients with viral infections, severe acute pancreatitis, and rejection reactions to kidney transplants. A-SAA has greater clinical diagnostic value in patients who are immunosuppressed, patients with cystic fibrosis who are treated with corticoids, and preterm infants with late-onset sepsis. Nevertheless, for the assessment of the inflammation status and identification of viral infection in other pathologies, such as bacterial infections, the combinatorial use of A-SAA and other acute-phase proteins (APPs), such as CRP and procalcitonin (PCT), can provide more information and sensitivity than the use of any of these proteins alone, and the information generated is important in guiding antibiotic therapy. In addition, A-SAA-associated diseases and the diagnostic value of A-SAA are discussed. However, the relationship between different A-SAA isotypes and their human diseases are mostly derived from research laboratories with limited clinical samples. Thus, further clinical evaluations are necessary to confirm the clinical significance of each A-SAA isotype. Furthermore, the currently available A-SAA assays are based on polyclonal antibodies, which lack isotype specificity and are associated with many inflammatory diseases. Therefore, these assays are usually used in combination with other biomarkers in the clinic.

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.

Is neutrophil gelatinase-associated lipocalin a good diagnostic marker for renal injury in asphyxiated preterm infants?

BACKGROUND

The objective of this study is to evaluate the value of neutrophil gelatinase-associated lipocalin (NGAL) for becoming a good endogenous marker of renal function in asphyxial preterm babies.

MATERIALS AND METHODS

This is a two-center retrospective study. Between October 2016 and October 2017, 71 asphyxial preterm infants were included in asphyxia group. Seventy babies were randomly included in control group. Samples were tested at 24, 48, and 96 h after birth. Quantitative data were compared by independent sample t-test or repeated measures ANOVA. For qualitative data, Pearson's Chi-squared test was performed. Draw ROC and compare the area under the curve (AUC), 95% confidence interval for AUC, specificity (Spe), sensitivity (Sen), and Youden index (Sen+Spe-1) at 24-h, 48-h, and 96-h time points.

RESULTS

(1) There are no significant differences concerning on baseline data. However, blood gas, Apgar score, and resuscitation showed a significant difference (P < 0.05). (2) In 24-h samples, only uNGAL and estimated glomerular filtration rate (eGFR) showed differences between the two groups (P < 0.05). In 48-h samples, significant differences could be found in uKIM-1, uNGAL, blood urea nitrogen, and eGFR (P < 0.05). In 96-h samples, almost all indicators have significant differences except urine output and eGFR (P < 0.05). (3) All biomarkers showed statistical difference in the three time points (P < 0.05), but only uNGAL showed a downward trend after the increase of expression. (4) uNGAL has better Sen and Spe than other indicators (24-h AUC 0.870, Youden index 0.606; 48-h AUC 0.879, Youden index 0.692; and 96-h AUC 0.806, Youden index 0.606).

CONCLUSION

uNGAL has a better distinguishability in asphyxial neonates compared with other indicators. Certainly, a larger sample, prospective study is still needed.

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.

Incidence of elevated procalcitonin and presepsin levels after severe trauma: a pilot cohort study

Procalcitonin (PCT) and presepsin (PSEP) are useful biomarkers for diagnosing sepsis; however, elevated PCT and PSEP levels may be observed in conditions other than sepsis. We hypothesised that PCT and PSEP levels could increase after severe traumatic injuries. Trauma patients with an Injury Severity Score of ≥16 from October 2013 to September 2015 were enrolled in our study. We examined PCT and PSEP levels and their positive rates on days 0 and 1. PCT and PSEP levels on days 0 and 1 were compared. Risk factors for increasing sepsis biomarker levels were identified by multivariate logistic regression analyses. In this study, 75 patients were included. PCT levels on days 0 and 1 were 0.1±0.4 and 1.8±6.3 ng/ml, respectively (P=0.02). PSEP levels on days 0 and 1 were 221±261 and 222±207 pg/ml, respectively (P=0.98). As per multivariate logistic regression analyses, packed red blood cell (PRBC) transfusion was the only independent risk factor for higher PCT levels on day 1 (P=0.04). Using PCT to diagnose sepsis in trauma patients on day 1 requires caution. PRBC transfusion was found to be a risk factor for increasing PCT levels. On the other hand, PSEP levels were not affected by trauma during the early phases.

Infectious Etiologies and Patient Outcomes in Pediatric Septic Shock

BACKGROUND

Septic shock remains an important cause of death and disability in children. Optimal care requires early recognition and treatment.

METHODS

We evaluated a retrospective cohort of children (age <19) treated in our emergency department (ED) for septic shock during 2008-2012 to investigate the association between timing of antibiotic therapy and outcomes. The exposures were (1) receipt of empiric antibiotics in ≤1 hour and (2) receipt of appropriate antibiotics in ≤1 hour. The primary outcome was development of new or progressive multiple system organ dysfunction syndrome (NP-MODS). The secondary outcome was mortality.

RESULTS

Among 321 patients admitted to intensive care, 48% (n = 153) received empiric antibiotics in ≤1 hour. These patients were more ill at presentation with significantly greater median pediatric index of mortality 2 (PIM2) scores and were more likely to receive recommended resuscitation in the ED (61% vs 14%); however, rates of NP-MODS (9% vs 12%) and hospital mortality (7% vs 4%) were similar to those treated later. Early, appropriate antibiotics were administered to 33% (n = 67) of patients with identified or suspected bacterial infection. These patients had significantly greater PIM2 scores but similar rates of NP-MODS (15% vs 15%) and hospital mortality (10% vs 6%) to those treated later.

CONCLUSIONS

Critically ill children with septic shock treated in a children's hospital ED who received antibiotics in ≤1 hour were significantly more severely ill than those treated later, but they did not have increased risk of NP-MODS or death.

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.

Clinical values of the early detection of serum procalcitonin, C-reactive protein and white blood cells for neonates with infectious diseases

OBJECTIVE

To discuss application values of serum procalcitonin (PCT), C-reactive protein (CRP) and white blood cells (WBC) count in early diagnosis and treatment of neonatal bacterial infectious diseases.

METHODS

Clinical data of one hundred and thirty-six newborns with infectious diseases who were admitted into the hospital were retrospectively analyzed. They were divided into bacterial infection group (N=70) and non-bacterial infection group (N=66). Additionally, sixty-six healthy newborns who underwent physical examination in our hospital in the same period were selected as controls. Subjects in the three groups were all detected for serum PCT, CRP and WBC levels.

RESULTS

The levels of PCT, CRP and WBC in the bacterial infection group were much higher than those of the non-bacterial infection group and the healthy control group, and the differences had statistical significance (P<0.05). The positive rates of PCT, CRP and WBC of the bacterial infection group were higher than those of the non-bacterial infection group (P<0.05); the specificity and sensitivity of the PCT level were obviously higher than those of the CRP and WBC levels in diagnosing bacterial infectious diseases (P<0.05).

CONCLUSION

Serum PCR, CRP and WBC levels are of high diagnostic values to neonatal infectious diseases. Compared to WBC and CRP, PCT is more sensitive index in the diagnosis of neonatal infectious diseases.

Procalcitonin

Procalcitonin (PCT) is the 116 amino acid precursor of the hormone calcitonin, produced by the C cells of the thyroid. Its synthesis is upregulated in bacterial infection and downregulated by viral infection. Consequently, with the increasing development of antibiotic resistance, interest has focused on the ability of this marker to not only diagnose infection but to tailor antibiotic treatment and help reduce the development of antibiotic resistance. The value of PCT depends on the specific clinical situation and pretest probability of disease. This article discusses the role of PCT in these different situations, namely primary care, the emergency department and the intensive care unit. The true cost effectiveness of this test remains difficult to prove as evidence for the potential impact of using PCT on slowing the development of bacterial resistance remains largely circumstantial.

Recognition and Management of Sepsis in Children: Practice Patterns in the Emergency Department

BACKGROUND

Pediatric sepsis remains a leading cause of morbidity and mortality. Understanding current practice patterns and challenges is essential to inform future research and education strategies.

OBJECTIVE

Our aim was to describe the practice patterns of pediatric emergency physicians (PEPs) in the recognition and management of sepsis in children and to identify perceived priorities for future research and education.

METHODS

We conducted a cross-sectional, internet-based survey of members of the American Academy of Pediatrics, Section on Emergency Medicine and Pediatric Emergency Research Canada. The survey was internally derived, externally validated, and distributed using a modified Dillman methodology. Rank scores (RS) were calculated for responses using Likert-assigned frequency values.

RESULTS

Tachycardia, mental-status changes, and abnormal temperature (RS = 83.7, 80.6, and 79.6) were the highest ranked clinical measures for diagnosing sepsis; white blood cell count, lactate, and band count (RS = 73.5, 70.9, and 69.1) were the highest ranked laboratory investigations. The resuscitation fluid of choice (85.5%) was normal saline. Dopamine was the first-line vasoactive medication (VAM) for cold (57.1%) and warm (42.2%) shock with epinephrine (18.5%) and norepinephrine (25.1%) as second-line VAMs (cold and warm, respectively). Steroid administration increased with complexity of presentation (all-comers 3.8%, VAM-resistant shock 54.5%, chronic steroid users 72.0%). Local ED-specific clinical pathways, national emergency department (ED)-specific guidelines, and identification of clinical biomarkers were described as future priorities.

CONCLUSIONS

While practice variability exists among clinicians, PEPs continue to rely heavily on clinical metrics for recognizing sepsis. Improved recognition through clinical biomarkers and standardization of care were perceived as priorities. Our results provide a strong framework to guide future research and education strategies in pediatric sepsis.

The Use of Procalcitonin in Clinical Practice

Procalcitonin (PCT) has emerged as the most promising marker of infectious inflammation. This development is critical to the practicing doctor dealing with febrile patients with suspected sepsis. An ideal biomarker would provide data for early diagnosis, differentiation of bacterial from non-bacterial causes of inflammation and information about the clinical course and prognosis of the disease. PCT is an early biomarker that is present within 3 to 4 hours of the triggering infection. An undetectable PCT level would efficiently rule out systemic infection. PCT may also be viewed as a marker of resolving infection as it has a half-life of about 22 hours, and its blood level correlates with bacterial load. Thus, PCT may be used as a clinical tool for early diagnosis, prognosis and therapeutic guide. Automated platforms with short assay times and service that is available 24 hours a day have enabled clinicians to obtain rapid reliable results for the early diagnosis and timely monitoring of appropriate pharmacotherapy. Clinicians should use PCT as an adjunct to clinical and other diagnostic criteria.

Procalcitonin to predict bacterial coinfection in infants with acute bronchiolitis: a preliminary analysis

OBJECTIVE

The aim of this study was to conduct a preliminary analysis of serum procalcitonin (PCT) to predict bacterial coinfection in infants with acute bronchiolitis.

METHODS

Retrospective cohort chart review of 40 infants admitted with acute bronchiolitis to the pediatric intensive care unit. Logistic regression models were used to determine the association of PCT and white blood count with presence of bacterial coinfection defined by either positive culture or chest radiograph result.

RESULTS

Fifteen (38%) of 40 patients had a diagnosis of bacterial coinfection by positive culture (9/15) or chest radiograph (6/15). Procalcitonin (P < 0.0001) was significantly associated with bacterial coinfection. A cutoff value of 1.5 ng/mL had sensitivity of 0.80, specificity of 1.00, and area under the operating curve of 0.88. White blood count (P = 0.06) was borderline significant with sensitivity of 0.33, specificity of 0.96, and area under the operating curve of 0.67. Three of 15 patients were later found to have bacterial coinfection with initial PCT of less than 1.5 ng/mL. None had follow-up PCT measurements taken. Thirty-five of 40 were prescribed empiric antibiotic therapy, including 20 of 25 patients without evidence of bacterial coinfection. None had a PCT of greater than 1.5 ng/mL. If a PCT cutoff of greater than 1.5 ng/mL had been used, 57% fewer patients would have received antibiotics with a 45% reduction in antimicrobial charges.

CONCLUSIONS

An elevated PCT may assist clinicians in determining presence of bacterial coinfection at admission in infants with acute bronchiolitis. Implementation of a PCT cutoff of 1.5 ng/mL at admission may prevent unnecessary antibiotic use with associated cost savings. Serial PCT levels may increase sensitivity. Further validation is warranted.

Lack of value of midregional pro-adrenomedullin and C-terminal pro-endothelin-1 for prediction of severe bacterial infections in infants with fever without a source

The study was performed to assess the usefulness of two new biomarkers, midregional pro-adrenomedullin (MR-pro-ADM) and C-pro-endothelin-1 (CT-pro-ET-1), in predicting bacterial infection (BI) and especially invasive bacterial infection (IBI) in well-appearing infants with fever without source (FWS). For this purpose, a multicenter prospective study was conducted between February 2008 and March 2009 including well-appearing infants less than 36 months of age with FWS. MR-pro-ADM, CT-pro-ET-1, procalcitonin (PCT), CRP, and WBC were measured and compared. Among the 1,035 infants included, a bacterial infection was diagnosed in 75 patients (7.2 %), and 16 (1.54 %) had an invasive bacterial infection (bacterial meningitis, 8; occult bacteremia, 6; and sepsis, 1). MR-pro-ADM and CT-pro-ET-1 levels were less reliable for diagnosis than the other biomarkers. The area under receiver operating characteristic curve for infants with BI and IBI was 0.59 (95 % confidence interval (CI) 0.52-0.67) and 0.63 (95 % CI 0.46-0.80) for MR-pro-ADM and 0.58 (95 % CI 0.51-0.66) and 0.62 (95 % CI 0.47-0.67) for CT-pro-ET-1, respectively. Multivariate analysis showed that PCT ≥ 0.5 ng/mL, CRP ≥ 40 mg/L, and CT-pro-ET-1 ≥ 105 pmol/mL were independent risk factors for having a BI (odds ratio (OR) 6.12, 3.61, and 2.84, respectively). PCT was the only independent risk factor for having an IBI (OR 17.53 if PCT ≥ 0.5 ng/mL).

CONCLUSION

Although baseline MR-pro-ADM and CT-pro-ET-1 levels are significantly elevated in well-appearing febrile infants with a bacterial infection, their overall performance as diagnostic markers is very poor.

Diagnostic value of procalcitonin in well-appearing young febrile infants

BACKGROUND AND OBJECTIVE

Procalcitonin (PCT) has been introduced in many European protocols for the management of febrile children. Its value among young, well-appearing infants, however, is not completely defined. Our objective was to assess its performance in diagnosing serious bacterial infections and specifically invasive bacterial infections (IBIs) in well-appearing infants aged <3 months with fever without source (FWS).

METHODS

Well-appearing infants aged <3 months with FWS admitted to 7 European pediatric emergency departments were retrospectively included. IBI was defined as the isolation of a bacterial pathogen in blood or cerebrospinal fluid culture.

RESULTS

We included 1112 infants who had PCT measured and a blood culture performed. IBI was diagnosed in 23 cases (2.1%). In the multivariate analysis including clinical and laboratory data, PCT was the only independent risk factor for IBI (odds ratio 21.69; 95% confidence interval [CI] 7.93-59.28 for PCT ≥ 0.5 ng/mL). Positive likelihood ratios for PCT ≥ 2 ng/mL and C-reactive protein (CRP) >40 mg/L were 11.14 (95% CI 7.81-15.89) and 3.45 (95% CI 2.20-5.42), respectively. Negative likelihood ratios for PCT <0.5 ng/mL and CRP <20 mg/L were 0.25 (95% CI 0.12-0.55) and 0.41 (95% CI 0.22-0.76). Among patients with normal urine dipstick results and fever of recent onset, areas under the receiver operator characteristic curve for PCT and CRP were 0.819 and 0.563, respectively.

CONCLUSIONS

Among well-appearing young infants with FWS, PCT performs better than CRP in identifying patients with IBIs and seems to be the best marker for ruling out IBIs. Among patients with normal urine dipstick results and fever of recent onset, PCT remains the most accurate blood test.

Procalcitonin-guided antibiotic treatment of respiratory tract infections in a primary care setting: are we there yet?

Clinical signs of infection do not allow for correct identification of bacterial and viral aetiology in acute respiratory infections. A valid tool to assist the clinician in identifying patients who will benefit from antibiotic therapy, as well as patients with a potentially serious infection, could greatly improve patient care and limit excessive antibiotic prescriptions. Procalcitonin is a new marker of suspected bacterial infection that has shown promise in guiding antibiotic therapy in acute respiratory tract infections in hospitals without compromising patient safety. Procalcitonin concentrations in primary care are low and can be used primarily to rule out serious infection. However, procalcitonin measurement should not be used as the sole basis for clinical decisions; clinical skills are prerequisites for the correct use of this new tool in practice. At present there is no point-of-care test for procalcitonin with acceptable precision, severely hampering its application in primary care. This article reviews the physiology of procalcitonin, describes the assays available for its measurement, evaluates the present evidence from primary care on its use to identify correctly patients who are likely to benefit from antibiotic treatment and to rule out serious infections, and comments on further research to determine a future role for procalcitonin in primary care.

Early diagnosis of sepsis using serum biomarkers

Sepsis, an innate immunological response of systemic inflammation to infection, is a growing problem worldwide with a relatively high mortality rate. Immediate treatment is required, necessitating quick, early and accurate diagnosis. Rapid molecular-based tests have been developed to address this need, but still suffer some disadvantages. The most commonly studied biomarkers of sepsis are reviewed for their current uses and diagnostic accuracies, including C-reactive protein, procalcitonin, serum amyloid A, mannan and IFN-γ-inducible protein 10, as well as other potentially useful biomarkers. A singular ideal biomarker has not yet been identified; an alternative approach is to shift research focus to determine the diagnostic relevancy of multiple biomarkers when used in concert. Challenges facing biomarker research, including lack of methodology standardization and assays with better detection limits, are discussed. The ongoing efforts in the development of a multiplex point-of-care testing kit, enabling quick and reliable detection of serum biomarkers, may have great potential for early diagnosis of sepsis.

The pathogenesis of sepsis

Sepsis is a serious clinical condition that represents a patient's response to a severe infection and has a very high mortality rate. Normal immune and physiologic responses eradicate pathogens, and the pathophysiology of sepsis is due to the inappropriate regulation of these normal reactions. In an ideal scenario, the first pathogen contact with the inflammatory system should eliminate the microbe and quickly return the host to homeostasis. The septic response may accelerate due to continued activation of neutrophils and macrophages/monocytes. Upregulation of lymphocyte costimulatory molecules and rapid lymphocyte apoptosis, delayed apoptosis of neutrophils, and enhanced necrosis of cells/tissues also contribute to the pathogenesis of sepsis. The coagulation system is closely tied to the inflammatory response, with cross talk between the two systems driving the dysregulated response. Biomarkers may be used to help diagnose patients with sepsis, and they may also help to identify patients who would benefit from immunomodulatory therapies.