Procalcitonin as an early marker of infection in neonates and children

Procalcitonin as a predictive marker of infections in chemoinduced neutropenia

PURPOSE

This study was designed to determine the usefulness of procalcitonin (PCT) as a predictive marker of infections in neutropenic patients following chemotherapeutic treatments.

METHODS

Over a 6-month period, 65 patients (34 affected by a solid tumor, 31 by a hematological disorder) were enrolled. Serum PCT concentrations were measured by an automated immunoassay on the leucocytes nadir and on the third day, when patients were checked for any sign of infection.

RESULTS

Procalcitonin values were not affected by gender, age, therapeutic approach, use of G-CSF or performance status and did not differ between patients who subsequently developed a localized infection and those who did not. PCT concentrations resulted higher in patients affected by hematological disorders than in those affected by solid tumors (mean value 0.09 vs. 0.05 microg/L; p < 0.0015) and in those who were hospitalized than in the outpatient group (0.10 vs. 0.05 microg/L; p < 0.0013). PCT levels correlated with the type of neoplastic disease (p = 0.016), the highest concentrations being detected in patients affected by acute leukemia.

CONCLUSIONS

These findings suggest that PCT is not a useful predictive marker of infection in oncohematologic neutropenic patients, even though higher serum PCT concentrations are associated with hematological tumors as well as in-hospital admission.

Host biomarkers and paediatric infectious diseases: from molecular profiles to clinical application

Infectious diseases are an important cause of death among children under the age of 5 (Stein et al., 2004). Most of these deaths are caused by preventable or curable infections. Limited access to medical care, antibiotics, and vaccinations remains a major problem in developing countries. But infectious diseases also continue to be an important public health issue in developed countries. With the help of modern technologies, some infections have been effectively controlled; however, new diseases such as SARS and West Nile virus infections are constantly emerging. In addition, other diseases such as malaria, tuberculosis, and bacterial pneumonia are increasingly resistant to antimicrobial treatment.

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

BACKGROUND

Procalcitonin and C-reactive-protein are inflammatory markers for sepsis. The authors evaluated their sensitivity and specificity in pediatric patients with cancer and febrile neutropenia.

PROCEDURE

Serum procalcitonin and C-reactive-protein were evaluated. Patients (n = 54) were divided into 2 groups, with severe infection (n = 18) or without documented infection (n = 36).

RESULTS

Procalcitonin and C-reactive protein were significantly higher in the high-risk group. Procalcitonin displayed 72.2% sensitivity and 80.5% specificity. C-reactive-protein had a sensitivity of 77.7% and specificity of 77.2%.

CONCLUSIONS

Procalcitonin is an accurate predictor of bacterial infection in neutropenic children, while C-reactive-protein may be a better screening test in emergency settings.

The use of procalcitonin in the diagnosis of late-onset infection in neonatal intensive care unit patients

We evaluated the semi-quantitative procalcitonin level for diagnosing late-onset infections in 176 neonates. Using a cut-off level of 0.5 ng/ml, the sensitivity was 84.4%+/-0.19, specificity was 93.9%+/-0.04, positive predictive value was 82.6%+/-0.1, and negative predictive value was 94.6%+/-0.04. Procalcitonin could be a useful marker of late-onset infection in neonates.

Contribution of procalcitonin to occult bacteraemia detection in children

We conducted a prospective study in 215 children, 3 to 36 months of age, presenting with fever > or = 39 degrees C without obvious origin, in order to evaluate the diagnostic value of procalcitonin (PCT) in detection of occult bacteraemia. PCT associated with white blood cell count constitutes an efficient screening method with sensitivity 100%, specificity 61.9% and positive and negative likelihoods ratios of 2.62 and 0, respectively.

Clinical decision rules for evaluating meningitis in children

PURPOSE OF REVIEW

Distinguishing between bacterial and aseptic meningitis in children is sometimes difficult. Guidelines recommend that patients with acute meningitis be systematically hospitalized and treated with antibiotics until the cerebrospinal fluid culture results are available. This strategy ensures rapid treatment for bacterial meningitis, but also involves unnecessary admissions and antibiotics for aseptic meningitis. Some authors have, therefore, proposed different combinations of predictors in clinical decision rules to distinguish as early as possible between bacterial and aseptic meningitis. To be useful, these rules must have near-100% sensitivity for bacterial meningitis, good specificity (to reduce unnecessary antibiotics and admissions), and easy bedside application.

RECENT FINDINGS

The present review examines the performance and level of validation of decision rules proposed after the Haemophilus influenzae vaccination entered widespread use. Most of these rules have been validated incompletely, if at all. Only one rule incorporates the best single validated predictive marker for distinguishing between bacterial and aseptic meningitis in children: serum procalcitonin level.

SUMMARY

Two rules are highly promising, meeting the three major conditions after a retrospective validation process in large samples. These rules can be applied cautiously to patients with the same inclusion and exclusion criteria as those in the derivation sets, while awaiting prospective multicenter validation studies.

Comparative efficacies of procalcitonin and conventional inflammatory markers for prediction of renal parenchymal inflammation in pediatric first urinary tract infection

OBJECTIVES

To compare the reliability of procalcitonin (PCT) with conventional laboratory parameters in predicting for renal parenchymal inflammation (RPI).

METHODS

The study cohort consisted of 57 children who were admitted for a first-episode urinary tract infection. All patients underwent measurement of the leukocyte count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and serum PCT. RPI was evaluated by technetium-99m dimercaptosuccinic acid (DMSA) scintigraphy within 7 days of admission. If the first DMSA findings were abnormal, another analysis was performed 6 months later. The cutoff points for ESR, CRP, and PCT were established by comparing the areas under their receiver operating characteristic curves. Statistical analysis was performed using 1-way analysis of variance.

RESULTS

Of the 57 children, 27 were diagnosed with RPI on the basis of positive DMSA results. The ESR, CRP, and PCT levels were significantly greater (P < .001) in the patients with RPI than in those without RPI. In contrast, the leukocyte count was the same in both groups (P > .05). PCT was a more sensitive and specific marker for differentiating upper and lower urinary tract infection than ESR and CRP. Persistent lesions at the site of previous RPI were found in 12 patients in the follow-up DMSA analysis, with total regression evident in the remaining 15. The PCT levels were significantly greater in those with persistent renal lesions than in those with total regression (P = .005).

CONCLUSIONS

Serum PCT is a more reliable biologic marker than the ESR, CRP, or leukocyte count for the early prediction of RPI in children with a first episode of urinary tract infection. In addition, the greater the elevation of PCT at admission, the more positive the correlation for subsequent permanent renal damage.

Is serum procalcitonin able to predict long-term kidney morbidity from urinary tract infections in children?

A new diagnostic strategy for children with febrile urinary tract infections could be the routine use of procalcitonin assessment to identify children requiring closer follow-up since being at risk for kidney damage. A total of 11 studies were published between 1998 and 2007. Children with very high procalcitonin levels during urinary tract infections are likely to be at risk of renal damage and vesico-ureteral reflux. Therefore, the prediction of long-term renal damage showed contradictory results. However, high procalcitonin values at diagnosis and positive scintigraphic scans may suggest the need to investigate for vesico-ureteral reflux. Consequently, procalcitonin levels should be included in follow-up protocols for urinary tract infections to aid in decision making concerning scintigraphic scans and voiding cystourethrograms.

Procalcitonin for the early prediction of renal parenchymal involvement in children with UTI: preliminary results

In order to establish the most reliable marker for distinguishing urinary tract infections (UTI) with and without renal parenchymal involvement (RPI), we recorded the clinical features and admission leukocyte count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and serum procalcitonin (PCT) in 57 children (including 43 girls) aged 2-108 months admitted with a first episode of UTI. RPI was evaluated by Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy within 7 days of admission. To establish cut-off points for ESR, CRP, and PCT, we used receiver operating characteristics curves and compared the area under the curve for ESR, CRP, and PCT. Twenty-seven children were diagnosed as having RPI based on positive renal scintigraphy. A body temperature of >38 degrees C, a history of diarrhea, and poor oral intake were more common in patients with RPI. ESR, CRP, and PCT, but not leukocyte count, were significantly higher in patients with RPI (P < 0.001). PCT was more sensitive and specific for the diagnosis of upper versus lower UTI than ESR and CRP. Using a cut-off value of 0.85 ng/ml, PCT had the best performance, with sensitivity, specificity, and positive and negative predictive values of 89%, 97%, 96%, and 91% respectively. Serum PCT is a better marker than ESR, CRP, and leukocyte count for the early prediction of RPI in children with a first episode of UTI.

Procalcitonin in young febrile infants for the detection of serious bacterial infections

OBJECTIVES

The objectives of the study were (1) to study the test performance of procalcitonin for identifying serious bacterial infections in febrile infants <or=90 days of age without an identifiable bacterial source and (2) to determine an optimal cutoff value to identify infants at low risk for serious bacterial infections.

METHODS

A prospective observational study was performed with febrile infants <or=90 days of age presenting to an urban, pediatric, emergency department. Serum procalcitonin levels were measured by using an automated high-sensitivity assay. An optimal procalcitonin cutoff value was selected to maximize sensitivity and negative predictive value for the detection of serious bacterial infections. Infants were classified as having definite, possible, or no serious bacterial infections.

RESULTS

A total of 234 infants (median age: 51 days) were studied. Thirty infants (12.8%) had definite serious bacterial infections (bacteremia: n = 4; bacteremia with urinary tract infections: n = 2; urinary tract infections: n = 24), and 12 infants (5.1%) had possible serious bacterial infections (pneumonia: n = 5; urinary tract infections: n = 7). Mean procalcitonin levels for definite serious bacterial infections (2.21 +/- 3.9 ng/mL) and definite plus possible serious bacterial infections (2.48 +/- 4.6 ng/mL) were significantly higher than that for no serious bacterial infection (0.38 +/- 1.0 ng/mL). The area under the receiver operating characteristic curve was 0.82 for definite serious bacterial infections and 0.76 for definite and possible serious bacterial infections. For identifying definite and possible serious bacterial infections, a cutoff value of 0.12 ng/mL had sensitivity of 95.2%, specificity of 25.5%, negative predictive value of 96.1%, and negative likelihood ratio of 0.19; all cases of bacteremia were identified accurately with this cutoff value.

CONCLUSIONS

Procalcitonin has favorable test characteristics for detecting serious bacterial infections in young febrile infants. Procalcitonin measurements performed especially well in detecting the most serious occult infections.

Procalcitonin assay in systemic inflammation, infection, and sepsis: clinical utility and limitations

OBJECTIVE

The use of procalcitonin (ProCT) as a marker of several clinical conditions, in particular, systemic inflammation, infection, and sepsis, will be clarified, and its current limitations will be delineated. In particular, the need for a more sensitive assay will be emphasized. For these purposes, the medical literature comprising clinical studies pertaining to the measurement of serum ProCT in various clinical settings was examined.

DATA SOURCE AND SELECTION

A PubMed search (1965 through November 2007) was conducted, including manual cross-referencing. Pertinent complete publications were obtained using the MeSH terms procalcitonin, C-reactive protein, sepsis, and biological markers. Textbook chapters were also read and extracted.

DATA EXTRACTION AND SYNTHESIS

Available clinical and other patient data from these sources were reviewed, including any data relating to precipitating factors, clinical findings, associated illnesses, and patient outcome. Published data concerning sensitivity, specificity, and reproducibility of ProCT assays were reviewed.

CONCLUSIONS

Based on available data, the measurement of serum ProCT has definite utility as a marker of severe systemic inflammation, infection, and sepsis. However, publications concerning its diagnostic and prognostic utility are contradictory. In addition, patient characteristics and clinical settings vary markedly, and the data have been difficult to interpret and often extrapolated inappropriately to clinical usage. Furthermore, attempts at meta-analyses are greatly compromised by the divergent circumstances of reported studies and by the sparsity and different timing of the ProCT assays. Although a high ProCT commonly occurs in infection, it is also elevated in some noninfectious conditions. Thus, the test is not a specific indicator of either infection or sepsis. Moreover, in any individual patient, the precipitating cause of an illness, the clinical milieu, and complicating conditions may render tenuous any reliable estimations of severity or prognosis. It also is apparent that even a febrile septic patient with documented bacteremia may not necessarily have a serum ProCT that is elevated above the limit of functional sensitivity of the assay. In this regard, the most commonly applied assay (i.e., LUMItest) is insufficiently sensitive to detect potentially important mild elevations or trends. Clinical studies with a more sensitive ProCT assay that is capable of rapid and practicable day-to-day monitoring are needed and shortly may be available. In addition, investigations showing that ProCT and its related peptides may have mediator relevance point to the need for evaluating therapeutic countermeasures and studying the pathophysiologic effect of hyperprocalcitonemia in serious infection and sepsis.

Non-infectious causes of elevated procalcitonin and C-reactive protein serum levels in pediatric patients with hematologic and oncologic disorders

BACKGROUND

Procalcitonin (PCT) is considered a sensitive and specific diagnostic and prognostic marker of systemic bacterial infection, but its value is questionable in certain clinical conditions, particularly in hemato-oncological patients.

MATERIALS AND METHODS

We analyzed PCT and C-reactive protein (CRP) levels in 56 patients of a pediatric hematology-oncology unit during 110 consecutive non-infectious febrile episodes related to administration of T-cell antibodies (group A; n = 22), alemtuzumab (monoclonal CD52 antibody, CAMPATH-1H/group B; n = 8), interleukin-2 (IL-2/group C; n = 41), prophylactic donor granulocyte transfusions (group D; n = 9), or to acute graft-versus-host disease (aGvHD/group E; n = 10) and compared the results with 20 episodes of Gram-negative sepsis (group F).

MAIN RESULTS

In the majority of the non-infectious episodes PCT and CRP increased to serum levels statistically indistinguishable from Gram-negative sepsis. Median peak levels of PCT (normal < 0.5 ng/ml)/CRP (normal < 8 mg/l) for groups A-F were 4.34/59.0 (A), 10.14/93.5 (B), 1.11/175.0 (C), 1.43/164 (D), 0.96/34.0 (E), and 8.14 ng/ml /126.0 mg/l (F). Highest single levels were observed in groups A and F.

CONCLUSIONS

PCT and CRP are of limited value as diagnostic markers of sepsis during T-cell-directed immunomodulatory treatment, granulocyte support, or acute GvHD.

[Laboratory studies in pediatric bone and joint infections]

The diagnosis of acute osteomyelitis and septic arthritis is a clinical one. Acute-phase reactants, such as white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) are useful to help the clinicians at the time of initial diagnosis. The WBC count may be normal in up to 80 % of cases and it is not a reliable indicator. The ESR is elevated in 80 % of cases. CRP is elevated more than 80 % of cases. CRP rises rapidly within 48 hours of admission and returns to normal within a week after appropriate therapy. Its rapid kinetics is useful for follow-up of the response treatment. Patients who require surgical drainage procedures have prolonged time to normalization of CRP. PCT is a useful specific marker for predicting severe infection but its sensibility to detect bone and joint infections seems to be low.

The evolving approach to the young child who has fever and no obvious source

Fever is a common complaint of young children who seek care in the emergency department. Recent advances, such as universal vaccination with the pneumococcal conjugate vaccine, require the review of traditional approaches to these patients. This article discusses newer strategies in the evaluation and management of the young child with fever, incorporating changes based on the shifting epidemiology of bacterial infection.

Streptococcus pneumoniae bacteraemia in children

Occult bacteraemia is the most frequent invasive disease caused by Streptococcus pneumoniae in children less than 3 years of age. Despite the relative frequency of this infection, its management is still a challenging task for paediatricians because fever is often the only symptom and a considerable overlap exists in the clinical presentation of children with fever without a focus due to viral illness and children with occult bacteraemia. Management protocols take into account the age of the patient, the clinical score for severity and the results of laboratory tests such as the white blood cell count, the C-reactive protein and the blood procalcitonin level in order to define accurately who will benefit from an antibiotic treatment. Despite appropriate healthcare facilities and access to care the case fatality rate in developed countries is around 9% in children aged less than 1 year. Prevention with the 7-valent conjugate vaccine against S. pneumoniae will decrease morbidity and mortality associated with invasive disease due to these bacteria. However, replacement by non-vaccine serotypes has been noted in countries where the vaccine is widely used and this concern needs to be monitored carefully over the next few years.

Low levels of procalcitonin during episodes of necrotizing enterocolitis

The pathogenesis of necrotizing enterocolitis (NEC) remains poorly understood. We aimed to assess the extent of bacterial infection in the pathogenesis of NEC using serial procalcitonin measurements. Blood samples were drawn during the first 4 days following every clinical event requiring a workup for presumed NEC. Eight episodes were confirmed as NEC, 7 of which showed procalcitonin levels <1 ng/ml at presentation and <1.3 ng/ml thereafter, comparable to 24 healthy controls. The one infant with elevated procalcitonin had bacteremia in addition to NEC. Procalcitonin levels of 24 matched septic infants were higher than those of NEC infants, peaking at 4.1 ng/ml. We conclude that low procalcitonin values are the rule during episodes of NEC and provide further evidence that overactive local immune response, and not active infection, is primarily responsible for the mucosal damage in NEC.

Procalcitonin and C-reactive protein as diagnostic markers of severe bacterial infections in febrile infants and children in the emergency department

OBJECTIVE

To assess the value of procalcitonin (PCT) and C-reactive protein (CRP), compared with that of total white-blood cell count (WBC) and absolute neutrophil count (ANC), in predicting severe bacterial infections (SBIs) in febrile children admitted to Emergency Department.

METHODS

A prospective study was conducted in 408 children aged 7-days to 36-months, admitted with fever without source, at a tertiary care Pediatric Emergency Department. PCT, CRP, WBC, and ANC were determined upon admission and compared. Specificity, sensitivity, multilevel likelihood ratios, receiver operating characteristic (ROC) analysis, and multivariate stepwise logistic regression were carried out.

RESULTS

SBI was diagnosed in 94 children (23.1%). PCT, CRP, WBC, and ANC were significantly higher in this group than in non-SBI patients. The area under the ROC (AUC) obtained was 0.82 (95% CI: 0.78-0.86) for PCT, 0.85 (95% CI: 0.81-0.88) for CRP (P = 0.358), 0.71 (95% CI: 0.66-0.75) for WBC, and 0.74 (95% CI: 0.70-0.78) for ANC. Only PCT (OR: 1.32; 95% CI: 1.11-1.57; P < 0.001) and CRP (OR: 1.02; 95% CI: 1.01-1.03; P < 0.001) were retained as significant predictors of SBI in a multiple regression model. For infants with fever <8 hours (n = 45), AUC for PCT and CRP were 0.92 (95% CI: 0.80-0.98) and 0.75 (95% CI: 0.60-0.87), respectively (P = 0.056).

CONCLUSION

Both PCT and CRP are valuable markers in predicting SBI in children with fever without source and they perform better than WBC and ANC. PCT appears more accurate at the beginning of infections, but overall CRP may be the most convenient marker for its better sensitivity and feasibility.

Distinction between bacterial and viral infections

PURPOSE OF REVIEW

To commence proper treatment as rapidly as possible and to reduce unnecessary antibiotic treatments, timely knowledge of whether the infection is bacterial or viral in origin would be beneficial for the clinician. As a reliable prediction of the causative agent of bacterial infection is not possible based on clinical features, there is an ongoing need for sensitive and specific markers of bacterial infection.

RECENT FINDINGS

The most common differential diagnosis methods are reviewed here. It is also demonstrated that the measurement of the expression of complement receptors, particularly CR1 (CD35), on neutrophils can be a useful preliminary test to differentiate between bacterial and viral infections. In addition, a novel marker of local and systemic bacterial infections designated 'clinical infection score (CIS) point', which incorporates quantitative analysis of complement receptors on neutrophils and standard clinical laboratory data and displays 98% sensitivity and 97% specificity in distinguishing between bacterial and viral infections, is presented.

SUMMARY

We conclude that the diagnostic yield of measured individual variables in distinguishing between bacterial and viral infections increases upon combination.

Biomarkers in neonatal infection

Infected newborn infants are often difficult to differentiate from patients suffering from noninfective diseases. Whilst delaying treatment with antibiotics of infected infants may be fatal, widespread indiscriminate use in all cases with suspected bacterial infection could lead to both drug-induced complications and the development of multidrug-resistant organisms. Conventional biomarkers, such as blood cell counts and morphology, have serious limitations. Investigators in this area of research have, therefore, made strenuous efforts to discover more reliable biomarkers with superior diagnostic utilities and clinically relevant characteristics to help neonatal clinicians differentiate between infected and noninfected infants. The major classes of biomarkers in neonatal infection of recent interest will be discussed, including: acute phase reactants, cytokines, chemokines and leukocyte surface antigens. The application of these biomarkers to derive prognostic information useful to neonatal clinicians will also be considered.

Meningococcal disease deaths and the frequency of antibiotic administration delays

OBJECTIVE

Meningococcal disease (MCD) remains a medical emergency and a frequent cause of death in previously healthy individuals. We aimed to determine the frequency and cause of delays in antibiotic administration in a cohort of deaths.

METHODS

A retrospective chart review was undertaken on 140 hospitalised MCD deaths within New Zealand's serogroup B epidemic (1993-2004).

RESULTS

Death after hospital presentation occurred rapidly (median 12 h) with 70% dying within 24 h. Delays of more than 2 h in time-to-antibiotic post hospital presentation occurred in 29%. The major contributors to these delays were the failure to include MCD within the differential diagnosis and prolonged assessment times. Multivariate logistic regression analysis, undertaken by combining study deaths which had meningococcal bacterial load results (n=9) with a survivor cohort (n=126) from a previous study, confirmed bacterial load as a major predictor of death (OR 7.5 per log10 cfu/mL increase; 95% CI 2.2-25.3; p=0.001). A non-significant increased risk of death per hour of antibiotic delay was seen (OR 1.18; 95% CI 0.90-1.55; p=0.22).

CONCLUSIONS

Death from MCD occurred rapidly, with many patients not receiving antibiotics at the earliest opportunity. The introduction of recently developed rapid diagnostic markers into the identified delay-intervals could lead to a reduction in time-to-antibiotic and hopefully reduce case-fatality rates.

Serum amyloid A: an early and accurate marker of neonatal early-onset sepsis

OBJECTIVES

To evaluate the accuracy of serum amyloid A (SAA), an acute phase protein in the detection of neonatal early-onset sepsis, by means of a fast automated SAA kit.

STUDY DESIGN

Full-term infants <72 h of age, who had risk factors and/or were suspected of having sepsis, were eligible for study. The levels of SAA were taken at 0, 24 and 48 h post sepsis evaluation. Thirty matched infants served as a control group for comparing SAA concentrations.

RESULTS

Of 104 infants eligible for entry to the study, 23 had sepsis and 81 had not sepsis. The SAA levels of the septic group were significantly higher than those of the nonseptic group at 0, 24 and 48 h (P<0.01 for all time points). In comparison with C-reactive protein (CRP), SAA levels rose earlier and in a sharper manner, had higher levels and returned faster to normal values in infants with early onset sepsis. At 0 h post-sepsis evaluation, serum SAA had an overall better diagnostic accuracy for predicting early onset sepsis than CRP (sensitivity (96 vs 30%), specificity (95 vs 98%), positive predictive value (85 vs 78%), negative predictive value (99 vs 83%), positive likelihood ratio (19 vs 12), and negative likelihood ratio (0.05 vs 0.71).

CONCLUSIONS

SSA is advocated as an inflammatory marker of neonatal early-onset sepsis.

Procalcitonin serum levels in children undergoing chronic haemodialysis

Infections account for considerable morbidity and mortality in patients requiring haemodialysis (HD). Procalcitonin (PCT)-a low molecular weight protein of 13 kDa-helps one to distinguish viral from bacterial infections and to evaluate the severity of bacterial infections. We investigated (1) PCT baseline levels in eight children undergoing chronic HD with high-flux membranes and (2) changes in the serum levels of PCT, C-reactive protein (CRP) and beta-2-microglobulin (beta2-MG)-a peptide with biochemical characteristics similar to those of PCT-before and after haemodialysis sessions. Blood sampling was performed three times in the mid-week session. Serum PCT of the seven uninfected children before HD sessions was increased (0.75+/-0.07 ng/ml), whereas CRP levels were normal. PCT after dialysis decreased significantly by 40% (P<0.0001) compared with initial values, whereas CRP levels before and after HD were not different. beta2-MG decreased by 70%, probably due to different biochemical properties of both proteins. PCT serum levels 15 min and 60 min after the HD session remained unchanged in comparison with those at the end of the HD session, suggesting accumulation of PCT between HD sessions rather than HD-induced production to be responsible for the increased baseline PCT serum levels. We concluded that CRP serum levels were not affected by HD in our group. Moderately elevated baseline PCT serum levels that are presumably due to reduced renal clearance and uraemia and dialysis-ability of PCT should be taken into consideration. However, increase of serum PCT in patients with severe bacterial infections is generally massive (10-fold to 1,000-fold), suggesting a low risk for false negative results in such cases.

The role of procalcitonin as a predictor of nosocomial sepsis in preterm infants

AIM

To assess the role of procalcitonin in detecting nosocomial sepsis in preterm infants, after the onset of clinical symptoms.

SUBJECTS

100 preterm infants, 24-36 wk of gestation, were followed from the age of 3 d until discharge. Procalcitonin and C-reactive protein (CRP) levels were measured within 3 d of sepsis workup events.

RESULTS

141 blood samples were drawn from 36 infants during 85 episodes of sepsis workup performed between 4 and 66 d of life. Of these episodes, 51 (60%) were not a result of documented sepsis and thereby served as the negative comparison group. Median procalcitonin levels were higher in the septic group compared with the non-septic group at the time of the sepsis workup (2.7 vs 0.5 ng/ml, p=0.003), at 1-24 h after the sepsis workup (4.6 vs 0.6 ng/ml, p=0.003), and at 25-48 h (6.9 vs 2.0 ng/ml, p=0.016). Using high cutoff levels, both procalcitonin (2.3 ng/ml) and CRP (30 mg/l) had high specificity and positive predictive value (97%, 91% and 96%, 87%, respectively) but low sensitivity (48% and 41%, respectively) to detect sepsis. Areas under the ROC curve for procalcitonin and CRP were 0.74 and 0.73, respectively.

CONCLUSION

Procalcitonin >2.3 ng/ml or CRP >30 mg/l indicates a high likelihood for neonatal sepsis, and antibiotic therapy should be continued even in the presence of sterile cultures.

Elevated procalcitonin as a diagnostic marker in meningococcal disease

Patients with meningococcal disease who seek medical attention can create a diagnostic dilemma for clinicians due to the nonspecific nature of the disease's presentation. This study assesses the diagnostic accuracy of procalcitonin levels in the setting of meningococcal disease. Two emergency department cohorts (A and B) were studied between 2002 and 2005, during the current epidemic of serogroup B meningococcal disease in New Zealand. Cohort A consisted of 171 patients, all with confirmed meningococcal disease (84 children, 87 adults). Cohort B consisted of a large (n=1,524) consecutively recruited population of febrile patients who presented to the emergency department, 28 of whom had confirmed meningococcal disease. Within the meningococcal disease cohort (cohort A), the geometric mean procalcitonin level was 9.9 ng/ml, with levels being higher in children than in adults (21.6 vs. 4.6 ng/ml, p=0.01). The overall sensitivity of elevated procalcitonin, using a cutoff of 2.0 ng/ml in children and 0.5 ng/ml in adults, was 0.93 (95%CI: 0.88-0.96). Despite the higher cutoff level for paediatric patients, a trend towards greater sensitivity existed in children (0.96 vs. 0.90; p=0.08). Elevated procalcitonin was correlated with whole blood meningococcal load (r=0.50) and Glasgow Meningococcal Sepsis Prognostic Score (r=0.40). Within the cohort of patients who were febrile on presentation (cohort B), the specificity of elevated procalcitonin in meningococcal disease was 0.85 (95% CI: 0.83-0.87), the positive and negative likelihood ratios were 6.1 and 0.08, respectively, and the sensitivity of elevated procalcitonin (0.93; 95% CI: 0.76-0.99) was corroborated. Measurement of procalcitonin is a useful tool in patients with nonspecific febrile illnesses when the possibility of meningococcal disease is present. The diagnostic accuracy surpasses that of current early laboratory markers, allowing results to be used to guide decisions about patient management.

Values of C-reactive protein, procalcitonin, and Staphylococcus-specific PCR in neonatal late-onset sepsis

AIM

To evaluate the predictive value of relevant clinical and laboratory parameters (complete blood count (CBC), C-reactive protein (CRP), procalcitonin (PCT) and Staphylococcus-specific polymerase chain reaction (PCR)) in neonates with suspected late-onset sepsis (LOS).

METHODS

NICU neonates were prospectively followed for septic events. One hundred and eleven neonates developed 148 suspected septic events beyond 3 d of age. We recorded the clinical signs and laboratory abnormalities at onset of sepsis, serum CRP and PCT, Staphylococcus-specific PCR, microbiological data, and empiric antimicrobial therapy.

RESULTS

Variables significantly associated with subsequently confirmed LOS included hypotension (relative risk (RR) = 5.6, 95% CI 3.29-9.53), mechanical ventilation (RR = 2.46, 95% CI 1.24-4.86), immature/total neutrophil ratio (I/T) > 0.2 (RR = 5.13, 95% CI 2.54-10.31), CRP > 1.0 mg/dl (RR = 2.85, 95% CI 1.32-6.15), and small-for-gestational-age (SGA) status (RR = 2.13, 95% CI 1.03-4.38). PCT was not significantly associated with LOS. For detection of staphylococcal bacteremia, Staphylococcus-specific PCR showed: sensitivity 57.1%, specificity 94.7%, positive predictive value 53.3%, and negative predictive value 95.4%.

CONCLUSION

Hypotension, mechanical ventilation, I/T > 0.2, CRP > 1.0 mg/dl, and SGA status at onset of sepsis are significant predictors of proven neonatal LOS. Staphylococcus-specific PCR might be of value in ruling out staphylococcal sepsis.

Evaluation of serum C-reactive protein, procalcitonin, tumor necrosis factor alpha, and interleukin-10 levels as diagnostic and prognostic parameters in patients with community-acquired sepsis, severe sepsis, and septic shock

The diagnostic value of procalcitonin, C-reactive protein, tumor necrosis factor-alpha, and interleukin-10 levels in differentiating sepsis from severe sepsis and the prognostic value of these levels in predicting outcome were evaluated and compared in patients with community-acquired sepsis, severe sepsis, and septic shock in the first 72 h of admission to the hospital. Thirty-nine patients were included in the study. The severe sepsis and septic shock cases were combined in a single "severe sepsis" group, and all comparisons were made between the sepsis (n=21 patients) and the severe sepsis (n=18 patients) groups. Procalcitonin levels in the severe sepsis group were found to be significantly higher at all times of measurements within the first 72 h and were significantly higher at the 72nd hour in patients who died. Procalcitonin levels that remain elevated at the 72nd hour indicated a poor prognosis. C-reactive protein levels were not significantly different between the groups, nor were they indicative of prognosis. No significant differences in the levels of tumor necrosis factor-alpha were found between the sepsis and severe sepsis groups; however, levels were higher at the early stages (at admission and the 24th hour) in patients who died. Interleukin-10 levels were also higher in the severe sepsis group and significantly higher at all times of measurement in patients who died. When the diagnostic and prognostic values at admission were evaluated, procalcitonin and interleukin-10 levels were useful in discriminating between sepsis and severe sepsis, whereas tumor necrosis factor-alpha and interleukin-10 levels were useful in predicting which cases were likely to have a fatal outcome.

Procalcitonin in preterm infants during the first few days of life: introducing an age related nomogram

OBJECTIVE

To determine normal concentrations of procalcitonin in preterm infants shortly after birth and to assess its accuracy in detecting bacterial infection.

METHODS

Blood samples of 100 preterm infants were prospectively drawn during the first 4 days of life for determination of procalcitonin concentration. Infants were classified into four groups according to their sepsis status.

RESULTS

Mean (SD) gestational age and birth weight were 32 (2.9) weeks and 1682 (500) g respectively. A total of 283 procalcitonin concentrations from healthy infants were plotted to construct nomograms of physiologically raised procalcitonin concentration after birth, stratified by two groups to 24-30 and 31-36 weeks gestation. The peak 95th centile procalcitonin concentration was plotted at 28 hours of age; values return to normal after 4 days of life. Only 12 infants were infected, and 13 of their 16 procalcitonin concentrations after birth were higher than the 95th centile, whereas samples taken at birth were lower. In a multivariable analysis, gestational age, premature rupture of membrane, and sepsis status influenced procalcitonin concentration independently, but maternal infection status did not.

CONCLUSIONS

The suggested neonatal nomograms of preterm infants are different from those of term infants. Procalcitonin concentrations exceeding the 95th centile may be helpful in detecting congenital infection, but not at birth.

Serum procalcitonin and other biologic markers to distinguish between bacterial and aseptic meningitis

OBJECTIVE

To identify the biologic tests that best distinguish between bacterial and aseptic meningitis in an emergency department (ED).

STUDY DESIGN

All children hospitalized for bacterial meningitis between 1995 and 2004 or for aseptic meningitis between 2000 and 2004 were included in a retrospective cohort study. Predictive values of blood (C-reactive protein, procalcitonin [PCT], white blood cell [WBC] count, neutrophil count) and cerebrospinal fluid (CSF) findings (protein, glucose, WBC count, neutrophil count) available in the ED were determined. Tests with the best predictive value were identified by using univariate and multivariate analyses and ROC curves comparison.

RESULTS

Among the 167 patients included, 21 had bacterial meningitis. The CSF gram-stain and bacterial antigen test had 86% and 60% sensitivity rates, respectively. PCT (>/=0.5 ng/mL) and CSF protein (>/=0.5 g/L) were the best biologic tests, with 89% and 86% sensitivity rates, 89% and 78% specificity rates, adjusted odds ratios of 108 (95% CI, 15-772) and 34 (95% CI, 5-217), and areas under the ROC curves of 0.95 and 0.93, respectively.

CONCLUSION

PCT and CSF protein had the best predictive value to distinguish between bacterial and aseptic meningitis in children.

Clinical significance of serum procalcitonin levels in patients with acute or chronic liver disease

OBJECTIVE

To evaluate the diagnostic value of serum procalcitonin levels in patients with acute or chronic liver disease, with or without bacterial infections and to correlate the results with the clinical outcome and the laboratory findings for these patients.

METHODS

One hundred and six consecutive hospitalized patients with liver disease were evaluated for procalcitonin levels on admission. Fifteen of them (14.2%) had acute alcoholic hepatitis on cirrhotic background (group A), 20 (18.9%) had alcoholic cirrhosis without hepatitis and/or bacterial infection (group B), 16 (15.1%) had decompensated cirrhosis with proved bacterial infection (group C), 42 (39.6%) had uncomplicated viral hepatitis-related cirrhosis (group D) and 13 (12.3%) had acute icteric viral hepatitis (group E). Serum procalcitonin levels were measured using an immunoluminometric assay. Statistical analysis was based on Student's t-test and the non-parametric Kruskall-Wallis test (P<0.05).

RESULTS

Serum procalcitonin levels were significantly higher in cirrhotic patients with bacterial infection (9.80+/-16.80 ng/ml) than in those without bacterial infection (0.21+/-0.13 ng/ml, P=0.001), whereas they were within normal range (<0.5 ng/ml) in all patients with uncomplicated cirrhosis, irrespective of the cause of cirrhosis. Seven of 15 group A patients (46.2%) and 4/13 group E patients (30.8%), all of them cirrhotics, had procalcitonin levels higher than 0.5 ng/ml on admission, without established bacterial infection.

CONCLUSION

Serum procalcitonin levels remain below the threshold of 0.5 ng/ml in all patients with uncomplicated cirrhosis, irrespective of the cause of the disease, while they are significantly elevated when bacterial infection complicates the course of the disease. A significant proportion of patients with acute alcoholic hepatitis on a cirrhotic background as well as of patients with acute on chronic viral hepatitis, without bacterial infection, exhibit serum procalcitonin levels above 0.5 ng/ml, suggesting that this cut-off value is probably not enough to discriminate between patients with or without bacterial infection within these subgroups of patients with liver disease.

Diagnostic markers for neonatal sepsis

PURPOSE OF REVIEW

To review the current evidence on the use of infection markers for diagnostic evaluation of sepsis in neonates.

RECENT FINDINGS

Recent research in immunology has led to the discovery of cell surface antigens, chemokines, cytokines and acute phase proteins that can potentially be used to 'rule in' or 'rule out' sepsis. The diagnostic utilities of key inflammatory mediators, including CD11b, CD64, interleukin-6 and interleukin-8, are promising and likely to become increasingly used as markers of infection for both diagnostic and prognostic purposes.

SUMMARY

Serial measurements and use of combinations of markers have been reported to improve sensitivity and negative predictive value of these tests. Current markers are not infallible, however, and do not permit neonatologists to withhold antibiotics in sick infants with suspected infection. Thus, many have emerged as useful indicators for early discontinuation of unnecessary antimicrobial therapy. Some infection markers are also useful for identifying infants with severe infection and adverse prognosis. Advances in flow cytometry have allowed simultaneous measurement of key markers using only minimal blood volume. Judicious selection of a panel of markers with complementary properties could greatly increase the ability of neonatologists to diagnose infection and discern valuable prognostic information.

Fever without source in children 0 to 36 months of age

Although fever in the young child (0-36 months) is a common clinical problem, the evaluation and treatment of febrile children remain controversial. Furthermore, universal vaccination with the heptavalent pneumococcal conjugate vaccine (PCV7) has changed the epidemiology of invasive bacterial disease in young children. This article addresses the approach to febrile neonates (0-28 days old), young infants (1-3 months old), and older infants and toddlers (3-36 months old) in the PCV7 era.

Inflammatory mediators for the diagnosis and treatment of sepsis in early infancy

Interleukin-6 (IL-6), interleukin-8 (IL-8), and procalcitonin (PCT) are important parameters in the diagnosis of sepsis and for differentiating between viral and bacterial infection in children. We compared the value of IL-6, IL-8, and PCT with C-reactive protein (CRP) in the diagnosis and treatment of late-onset sepsis among infants admitted to the neonatal intensive care unit (group I) and febrile infants admitted to general hospitals from home (group II). Group I was divided into subgroups Ia, positive blood culture (all Gram-positive cocci); Ib, negative blood culture; and Ic, controls. Group II was divided into subgroups IIa, systemic enterovirus infection, and IIb, no enterovirus infection. Enterovirus was identified by real-time (RT) polymerase chain reaction (PCR) and/or by culture in blood and cerebrospinal fluid (CSF). The positive predictive values of IL-6, IL-8, and PCT (78%, 72%, and 83%, respectively) were better than that of CRP (63%) in the diagnosis of neonatal sepsis. After 48 h of antibiotic treatment, IL-6 and IL-8 levels significantly decreased and PCT stabilized in clinically recovered patients, suggesting that these markers may be useful in distinguishing patients in which antibiotic treatment may be discontinued. Among infants of subgroup IIa, 80%-90% had normal values of IL-6, IL-8, and PCT, whereas CRP was increased in 40%. In conclusion, IL-6, IL-8, and PCT are better parameters than CRP in the diagnosis and follow-up of neonatal sepsis due to coagulase-negative staphylococci (CoNS) and in the exclusion of bacterial infection among those with enteroviral infection among febrile infants presenting from home.

Biomarkers of sepsis: clinically useful?

PURPOSE OF REVIEW

The purpose of this review is to indicate recent developments in biomarkers of sepsis and to evaluate their impact on clinical use. According to the 'surviving sepsis campaign,' diagnosis of sepsis and infection is urgent; early and specific treatment is most effective to reduce complications and to decrease mortality.

RECENT FINDINGS

A variety of biomarkers of sepsis is presently available. The diagnostic spectrum of the various markers, however, is different. Some primarily indicate severity of inflammation (e.g. interleukin-6), others respond to infection, but do not indicate the host response well (endotoxin, lipoprotein binding protein, triggering receptor on myeloid cells). There are new markers with limited clinical experience, for example triggering receptor on myeloid cells or mid-pro atrial natriuretic peptide (Seristra, Brahms AG, Hennigsdorf, Germany). Procalcitonin is a well-established biomarker of sepsis that fulfills several criteria of clinical needs: it responds both to infection and severity of inflammation and thus has an impact on therapy. Recent studies indicate that antibiotic treatment can also be guided by procalcitonin. Further indications, including diagnosis of invasive bacterial infections and diagnosis of sepsis in neonates and children have been reported recently.

SUMMARY

Recent data and cumulative analyses indicate that biomarkers of sepsis improve diagnosis of sepsis. However, only a few markers have impact on therapy and fulfill the clinical requirements. Procalcitonin is a well-established marker, indicating infection, sepsis, and progression to the more severe stages of the disease. Today, this biomarker should be in the diagnostic portfolio of an intensive care unit or emergency ward.

Overprescribing of antibiotics to children in rural Vietnam

100 children (aged 1-6 y), who received an antibiotic prescription after health examination in the Bavi health care system (79 children at a district hospital, 21 at a community health centre) were analysed regarding antibiotics prescribed in relation to serum C-reactive protein (CRP). A control group consisted of 35 healthy children. Children who had been treated with antibiotics within 1 week prior to the study were excluded in the community health centre and control groups. Capillary blood samples were collected and the serum CRP concentration was analysed. A questionnaire interview with the carers was performed. Elevated CRP concentrations (>10 mg/l) were detected in 17 (17%) of the study population, and only 2 had a CRP level above 25 mg/l, one 36 mg/l and the other 140 mg/l. In the control group, none of the children had elevated CRP. The most common diagnoses were acute respiratory tract infection (ARI, 55%), asthma (7%), tonsillitis (4%), and diarrhoea (4%). The average number of drugs per patient was 3.1, and 77% received vitamins and 15% corticosteroids in combination with antibiotics. A majority of children who received an antibiotic prescription based on clinical examination did not have an elevated CRP and overprescribing of antibiotics was thus indicated.

Community-acquired pneumonia in children

PURPOSE OF REVIEW

This review highlights recent developments in the diagnosis, etiology, therapy, and prevention of community-acquired pneumonia in children.

RECENT FINDINGS

Sensitive new diagnostic methods have increased the detection rate of the causative agent up to 94%. Streptococcus pneumoniae is the most prevalent bacterial pathogen in all ages. Polymerase chain reaction is a rapid and sensitive method for the detection of Chlamydia pneumoniae and Mycoplasma pneumoniae, which have gained greater importance in recent years. During the period covered by this review, two new agents causing pneumonia were extensively studied. Human metapneumonovirus detected in young children is a leading cause of respiratory disease during the first years of life. A novel coronavirus was identified as the causative agent of severe respiratory syndrome, a new respiratory illness that affects adults and children. One multicenter trial concluded that nonsevere pneumonia can be treated with a short course of oral amoxicillin and a multicenter international study showed that children with severe pneumonia have similar outcomes whether treated with oral amoxicillin or parenteral penicillin, but more data are needed to demonstrate the safety and efficacy of such regimens.

SUMMARY

The continued evolution of bacterial resistance highlights the need for appropriate use of antibacterials. Improved diagnostic techniques will aid the treatment of children with community-acquired pneumonia. Aggressive vaccination with the pneumococcal conjugate vaccine and other available vaccines as well as the development of new vaccines will aid the prevention of respiratory disease in children.

Improved diagnostic approaches to infection/sepsis detection

Sepsis is a major healthcare problem from the perspective of mortality and economics. Advances in diagnostic detection of infection and sepsis have been slow, but recent advances in both soluble biomarker detection and quantitative cellular measurements promise the availability of improved diagnostic techniques. Though the promise of cytokine measurements reaching clinical practice have not matured, procalcitonin levels are currently available in many countries and appear to offer enhanced diagnostic distinction between bacterial and viral etiologies. Cellular diagnostics is poised to enter clinical laboratory practice in the form of neutrophil CD64 measurements, which offer superior sensitivity and specificity to conventional laboratory assessment of sepsis. Neutrophil CD64 expression is negligible in the healthy state. However, it increases as part of the systemic response to severe infection or sepsis. The combination of cellular proteomics, as in the case of neutrophil CD64 quantification, and selected soluble biomarkers of the inflammatory response, such as procalcitonin or triggering receptor expressed on myeloid cells (TREM)-1, is predicted to remove the current subjectivity and uncertainty in the diagnosis and therapeutic monitoring of infection and sepsis.