Low-cost, facile droplet modification of screen-printed arrays for internally validated electrochemical detection of serum procalcitonin

This manuscript presents the design and facile production of screen-printed arrays (SPAs) for the internally validated determination of raised levels of serum procalcitonin (PCT). The screen-printing methodology produced SPAs with six individual working electrodes that exhibit an inter-array reproducibility of 3.64% and 5.51% for the electrochemically active surface area and heterogenous electrochemical rate constant respectively. The SPAs were modified with antibodies specific for the detection of PCT through a facile methodology, where each stage simply uses droplets incubated on the surface, allowing for their mass-production. This platform was used for the detection of PCT, achieving a linear dynamic range between 1 and 10 ng mL^-1 with a sensor sensitivity of 1.35 × 10^-10 NIC%/ng mL^-1. The SPA produced an intra- and inter-day %RSD of 4.00 and 5.05%, with a material cost of £1.14. Internally validated human serum results (3 sample measurements, 3 control) for raised levels of PCT (>2 ng mL^-1) were obtained, with no interference effects seen from CRP and IL-6. This SPA platform has the potential to offer clinicians vital information to rapidly begin treatment for "query sepsis" patients while awaiting results from more lengthy remote laboratory testing methods. Analytical ranges tested make this an ideal approach for rapid testing in specific patient populations (such as neonates or critically ill patients) in which PCT ranges are inherently wider. Due to the facile modification methods, we predict this could be used for various analytes on a single array, or the array increased further to maintain the internal validation of the system.

Change of serum lipoproteins and its potential use in stratifying patients with sepsis among neonates

BACKGROUND

Changes of serum lipoprotein concentration during bacteremia or sepsis are observed and lipoproteins concentration facilitate the evaluation severity of sepsis in adults, but its clinical usage is still unclear. Here, we analyzed the lipoprotein concentration in neonates with sepsis and discussed its use in stratifying patients.

METHODS

This is a retrospective study involved 88 culture-proven septic patients. Clinical and microbiology data of involved patients were collected via inquiring databases of our institute. Patients were grouped according to blood culture results or procalcitonin level; the difference between groups were analyzed.

RESULTS

Compared with uninfected group, there is no change of triglyceride (TG) concentrations and significant decrease of Total cholesterol (TC) concentration in septic patients. There is no significant difference between Gram-positive and Gram-negative-related septic patients in terms of serum TG and TC concentration. Other than group with procalcitonin level of 0.5-2 ng/ml, both serum TG and TC concentration were decreased while serum procalcitonin level increasing.

CONCLUSIONS

Our results indicated that serum lipoprotein concentration may be recommended to help diagnosis of bacteria and to evaluate the severity of sepsis.

Diagnosis of Neonatal Sepsis: The Role of Inflammatory Markers

This is a narrative review on the role of biomarkers in the diagnosis of neonatal sepsis. We describe the difficulties to obtain standardized definitions in neonatal sepsis and discuss the limitations of published evidence of cut-off values and their sensitivities and specificities. Maternal risk factors influence the results of inflammatory markers as do gestational age, the time of sampling, the use of either cord blood or neonatal peripheral blood, and some non-infectious causes. Current evidence suggests that the use of promising diagnostic markers such as CD11b, CD64, IL-6, IL-8, PCT, and CRP, either alone or in combination, might enable clinicians discontinuing antibiotics confidently within 24-48 h. However, none of the current diagnostic markers is sensitive and specific enough to support the decision of withholding antibiotic treatment without considering clinical findings. It therefore seems to be justified that antibiotics are often initiated in ill term and especially preterm infants. Early markers like IL-6 and later markers like CRP are helpful in the diagnosis of neonatal sepsis considering the clinical aspect of the neonate, the gestational age, maternal risk factors and the time (age of the neonate regarding early-onset sepsis) of blood sampling.

Evaluation of presepsin as a diagnostic tool in newborns with risk of early-onset neonatal sepsis

OBJECTIVES

To evaluate the efficacy of presepsin (P-SEP) as a potential biomarker of early-onset neonatal sepsis (EOS) and compare it to other routinely used markers of inflammation. To establish the cut-off values of P-SEP for EOS.

STUDY DESIGN

184 newborns were prospectively recruited between January 2018 to December 2020. Newborns >34th gestational week with suspected infection were included up to 72 h after delivery, and divided into three categories (i.e., unlikely, possible, and probable infection) based on risk factors, clinical symptoms and laboratory results. Values of plasma P-SEP were sequentially analyzed.

RESULTS

Median values of P-SEP in newborns with probable infection were significantly higher compared to healthy newborns (p = 0.0000013) and unlikely infection group (p = 0.0000025). The AUC for discriminating the probable infection group from the unlikely infection group was 0.845 (95% Cl: 0.708-0.921). The diagnostic efficacy of P-SEP was highest when used in combination with IL-6 and CRP (0.97; 95% CI: 0.911-0.990). The optimal cut-off value of P-SEP was determined to be 695 ng/L.

CONCLUSION

P-SEP, when combined with IL-6 and CRP, may be utilized as a negative predictive marker of EOS (NPV 97.2%, 95% CI: 93.3-101), especially in newborns at low to medium risk of infection.

Procalcitonin in Preterm Neonates: A Different Threshold and Prolonged Interpretation

Objectives: To evaluate the positive threshold of PCT for neonates of <32 weeks of gestation for the diagnosis of early-onset sepsis and to determine if the level of PCT collected within 6 h of life could be used. Design: Retrospective and bicentric study from May 2016 to April 2018. Setting: Two groups were established, neonates evaluated for PCT at birth (CordPCT) and within 6 h of life (delPCT). Patients: Two hundred and sixty neonates of <32 weeks of gestation born in Nice and South Paris (Bicêtre) University Hospitals, had been evaluated for PCT level. Main Outcomes Measures: The value of the PCT positive threshold was determined for the total population and each groups thanks ROC curves. Results: The threshold level of PCT for the total population was 0.98 ng/mL. The threshold value of cordPCT group was 1.00 vs. 0.98 ng/mL for delPCT group. The area under the Receiver Operating Characteristics curve for PCT sampled in delPCT group was significantly higher than in cordPCT group (0.94 compared to 0.75). Conclusions: The threshold level of PCT was higher in this cohort of neonates of <32 weeks of gestation compared to the value generally described for term neonates. The secondary sampling PCT level seems to be usable in screening algorithm for early-onset neonatal sepsis.

Procalcitonin Level at 24 Hours of Age May be Predictive for Transient Tachypnea of the Newborn

Objective It is an important problem to differentiate transient tachypnea of the newborn (TTN) from bacterial pneumonia or other conditions in patients admitted to Neonatal Intensive Care Unit. The aim of this study was to evaluate the predictive value of procalcitonin (PCT) for TTN.

Methods A total of 52 infants were contained in the study. The patients were divided into three groups. Group 1 consisted of patients with pronounced grunting at more than 2 hours postnatal age (n = 16). Group 2 consisted of patients whose grunt was reduced or gone at 2 hours postnatal age but in whom tachypnea persisted until 24 hours postnatal age (n = 18). Group 3 consisted of patients with minimal or no respiratory distress at 24 hours postnatal age (n = 18). In all groups, PCT concentrations were determined at birth and 24 hours postnatal age.

Results PCT concentrations at birth were significantly higher in Group 1 than other groups, but there was no difference between Groups 2 and 3. PCT concentrations at 24 hours postnatal age were significantly higher in Groups 1 and 2 than Group 3. No difference was found between Group 1 and Group 2 at 24 hours postnatal age. All PCT concentrations in Group 3 were significantly lower than other groups. PCT thresholds for the diagnosis of TTN were 0.44 ng/mL at birth (sensitivity 58%, specificity 50%) and 5.11 ng/mL at 24 hours postnatal age (sensitivity 79.4%, specificity 89.1%).

Conclusion Serial PCT measurements at birth and postnatal 24 hours may be helpful in differentiating between pneumonia and TTN. Further researches are needed to confirm this initial study.

The influencing factors on procalcitonin values in newborns with noninfectious conditions during the first week of life

Purpose

Although procalcitonin (PCT) level is useful for the diagnosis of neonatal sepsis, PCT reliability is inconsistent because of the varied conditions encountered in neonatal intensive care units. This study aimed to investigate PCT levels and factors influencing increased PCT levelin newborns without bacterial infection during the first week of life.

Methods

In newborns hospitalized between March 2013 and October 2015, PCT levels were measured on the first, third, and seventh days after birth. Newborns with proven bacterial (blood culture positive for bacteria) or suspicious infection (presence of C-reactive protein expression or leukocytosis/leukopenia) were excluded. Various neonatal conditions were analyzed to identify the factors influencing increased PCT level.

Results

Among 292 newborns with a gestational age of 35.2±3.0 weeks and a birth weight of 2,428±643 g, preterm newborns (n=212) had higher PCT levels than term newborns (n=80). Of the newborns, 7.9% had increased PCT level (23 of 292) on the firstday; 28.3% (81 of 286), on the third day; and 3.3% (7 of 121), on the seventh day after birth. The increased PCT level was significantly associated with prenatal disuse of antibiotics (P=0.004) and surfactant administration (P<0.001) on the first day after birth, postnatal use of antibiotics (P=0.001) and ventilator application (P=0.001) on the third day after birth, and very low birth weight (P=0.042) on the seventh day after birth.

Conclusion

In newborns without bacterial infection, increased PCT level was significantly associated with lower gestational age and respiratory difficulty during the first week of life. Further studies are needed for clinical applications.

Age-specific percentile-based reference curve of serum procalcitonin concentrations in Japanese preterm infants

Procalcitonin (PCT) levels are elevated early after birth in newborn infants; however, the physiological features and reference of serum PCT concentrations have not been fully studied in preterm infants. The aims of the current study were to establish an age-specific percentile-based reference curve of serum PCT concentrations in preterm infants and determine the features. The PCT concentration peaked in infants at 1 day old and decreased thereafter. At 1 day old, serum PCT concentrations in preterm infants <34 weeks’ gestational age were higher than those in late preterm infants between 34 and 36 weeks’ gestational age or term infants ≥37 weeks’ gestational age. Although the 50-percentile value in late preterm and term infants reached the adult normal level (0.1 ng/mL) at 5 days old, it did not in preterm infants. It took 9 weeks for preterm infants to reach it. Serum PCT concentrations at onset in late-onset infected preterm infants were over the 95-percentile value. We showed that the physiological feature in preterm infants was significantly different from that in late preterm infants, even in those <37 weeks’ gestational age. To detect late-onset bacterial infection and sepsis, an age-specific percentile-based reference curve may be useful in preterm infants.

Procalcitonin as a marker of respiratory disorder in neonates

BACKGROUND

Serum procalcitonin (PCT) increases in various respiratory disorders such as acute respiratory distress syndrome. Elevated PCT is also observed in healthy neonates. In this study, we investigated whether PCT is a good marker of respiratory disorder in neonates.

METHODS

A total of 155 neonates with or without respiratory disorder, were eligible for the study. PCT was measured on electrochemiluminescence immunoassay. Each neonate was allocated to the non-respiratory disorder (control) group (n = 95), or a respiratory disorder group (n = 60). PCT was compared between the groups, and association with other markers, including C-reactive protein (CRP) and white blood cell (WBC) count, was analyzed.

RESULTS

Of the 60 neonates in the respiratory disorder group, 39, 10, five, one, two, two, and one neonates had transient tachypnea of the newborn, respiratory distress syndrome, air leak syndrome, meconium aspiration syndrome, 18-trisomy, neonatal asphyxia, and congenital diaphragmatic hernia, respectively. Mean PCT, CRP and WBC count in the respiratory disorder group were 9.01 ng/mL, 0.26 mg/dL, and 16,100 cells/μL, respectively. The area under the curve obtained for PCT in distinguishing between the respiratory disorder and control groups was 0.85 (sensitivity, 66.7%; specificity, 93.0%; optimum cut-off, 3.73 ng/mL), that for CRP was 0.72 (sensitivity, 75.0%; specificity, 64.6%; optimum cut-off, 0.14 mg/dL), and for WBC it was 0.44 (sensitivity, 60.0%; specificity, 29.6%; optimum cut-off, 15,000 cells/μL).

CONCLUSIONS

PCT is more susceptible, as a diagnostic parameter of infection, to the effect of respiratory disturbance than CRP and WBC.

The role of proteomics in understanding biological mechanisms of sepsis

Sepsis is a systemic inflammatory state caused by infection. Complications of this infection with multiple organ failure lead to more lethal conditions, such as severe sepsis and septic shock. Sepsis is one of the leading causes of US deaths. Novel biomarkers with high sensitivity and specificity may be helpful for early diagnosis of sepsis and for improvement of patient outcomes through the development of new therapies. Mass spectrometry-based proteomics offers powerful tools to identify such biomarkers and furthermore to give insight to fundamental mechanisms of this clinical condition. In this review, we summarize findings from proteomics studies of sepsis and how their applications have provided more understanding into the pathogenesis of septic infection. Literatures related to "proteomics", "sepsis", "systemic inflammatory response syndrome", "severe sepsis", "septic infection", and "multiple organ dysfunction syndrome" were searched using PubMed. Findings about neonatal and adult sepsis are discussed separately. Within the adult sepsis studies, results are grouped based on the models (e.g., human or animal). Across investigations in clinical populations and in rodent and mammalian animal models, biological pathways, such as inflammatory and acute phase response, coagulation, complement, mitochondrial energy metabolism, chaperones, and oxidative stress, are altered at the protein level. These proteomics studies have discovered many novel biomarker candidates of septic infection. Validation the clinical use of these biomarker candidates may significantly impact the diagnosis and prognosis of sepsis. In addition, the molecular mechanisms revealed by these studies may also guide the development of more effective treatments.

Procalcitonin as a biomarker of acute lower respiratory tract infections

BACKGROUND

Procalcitonin (PCT) has emerged as a promising 'acute phase' biomarker used for diagnosis of acute bacterial infections of the respiratory tract. The introduction of new sensitive PCT assays has facilitated implementation of a new clinical approach to reduce antibiotic use in acute lower respiratory tract infections (LRTIs), without compromising patient safety.

OBJECTIVE

Current state of knowledge on the clinical usefulness of serum PCT measurements for the evaluation of acute LRTIs is presented herein, together with basic information on available rapid diagnostic tests for PCT measurement.

METHODS

During the literature search the emphasis was on PCT use as a diagnostic, monitoring and prognostic tool for acute LRTIs. The acute LRTIs have been defined as acute bronchitis, acute exacerbations of chronic obstructive pulmonary disease or asthma, and pneumonia. Original studies involving patients with these conditions have been considered, and recent articles documenting interventional trials on PCT use for guidance of antimicrobial treatment in LRTIs have been reviewed in particular.

RESULTS/CONCLUSION

When measured with sensitive and rapid assays, PCT has proved to be a good biomarker for acute bacterial LRTIs, which enables an early diagnosis, facilitates therapeutic decisions, and can inform clinicians about the course of disease and prognosis. PCT can become a particularly suitable tool for implementation in an emergency and acute medical care setting.

Procalcitonin and valuable clinical symptoms in the early detection of neonatal late-onset bacterial infection

AIM

To evaluate which clinical symptoms indicate proven neonatal bacterial infection (NBI) and whether measuring procalcitonin aside from C-reactive protein and interleukin 6 improves sensitivity and specificity in diagnosis.

METHODS

In a prospective observational study, clinical symptoms and procalcitonin, C-reactive protein and interleukin 6 were simultaneously determined from the 4th day of life in 170 preterm and term neonates at the first time of suspicion of NBI. Proven NBI was defined as a positive culture of otherwise sterile body fluids or radiologically verified pneumonia in combination with elevated inflammatory markers.

RESULTS

Fifty-eight (34%) patients were diagnosed with proven late-onset NBI. In case of proven NBI, odds ratio and 95% confidence intervals were 2.64 (1.06-6.54) for arterial hypotension, 5.16 (2.55-10.43) for feeding intolerance and 9.18 (4.10-20.59) for prolonged capillary refill. Sensitivity of combined determination of C-reactive protein (>10 mg/L) and interleukin 6 (>100 pg/mL) was 91.4%, specificity 80.4%, positive predictive value 70.7% and negative predictive value 94.7%. The additional determination of procalcitonin (>0.7 ng/mL) resulted in 98.3%, 65.2%, 58.8% and 98.6%, respectively.

CONCLUSION

Arterial hypotension, feeding intolerance and especially prolonged capillary refill indicate proven neonatal late-onset bacterial infection, even at the time of first suspicion. Additional measurement of procalcitonin does indeed improve sensitivity to nearly 100%, but is linked to a decline in specificity. Nevertheless, in the high-risk neonatal population, additional procalcitonin measurement can be recommended because all infants with NBI have to be identified.

[Procalcitonin-based algorithm. Management of antibiotic therapy in critically ill patients]

Sepsis is one of the most cost-intensive conditions of critically ill patients in intensive care medicine. Furthermore, sepsis is known to be the leading cause of morbidity and of mortality in intensive care patients. Early initiation of antibiotic therapy can significantly reduce mortality. The development of resistance of bacterial species against antibiotics is a compelling issue to reconsider indications and administration of antibiotic treatment. Adequate indications and duration of therapy are particularly important for the use of highly potent substances in the intensive care setting. Until recently no laboratory marker has been available to distinguish bacterial infections from viral or non-infectious inflammatory responses. However, procalcitonin (PCT) appears to be the first among a large array of inflammatory markers that offers this possibility. Regular procalcitonin measurements can significantly shorten the length of antibiotic therapy, show positive influence on antibiotic costs and have no adverse affects on patient outcome.

Procalcitonin measurement at 24 hours of age may be helpful in the prompt diagnosis of early-onset neonatal sepsis

BACKGROUND

The clinical signs of early-onset neonatal sepsis (EONS) are nonspecific and indistinguishable from those of noninfectious disorders. The early diagnosis of EONS is difficult, but is essential to improve outcomes. The aim of this study was to determine the diagnostic value of procalcitonin (PCT) at birth and at 24h of age in the prompt diagnosis of EONS.

METHODS

The patient group consisted of neonates with a Töllner score of ≥ 10 or a Töllner score of 5-10 but with the presence of prolonged rupture of the membranes (> 18 h) or chorioamnionitis or maternal fever (n=171). The control group (n=89) comprised neonates admitted to the neonatal intensive care unit for different disease entities. Procalcitonin levels at birth (first) and at 24h of age (second) were measured for each neonate in both of the study groups.

RESULTS

There was no difference between the two groups in terms of gender, birth weight, or gestational age. The mean (min-max) first PCT level was 0.48 (0.07-3.48)ng/ml in the controls and 0.51 (0.09-28.6)ng/ml in patients. The mean (min-max) second PCT level was 1.72 (0.21-18.23)ng/ml in the controls and 16.17 (0.17-100)ng/ml in patients. There was no statistically significant difference in PCT levels between the patient and control groups at birth. However, at 24h of age, PCT levels were significantly higher in the patient group than in the control group (p<0.001). Serum PCT levels in controls at 24h of age were slightly increased compared to levels at birth, but as a normal reaction. PCT thresholds for the diagnosis of sepsis were 0.59 ng/ml at birth (sensitivity 48.7%, specificity 68.6%) and 5.38 ng/ml at 24h of life (sensitivity 83.3%, specificity 88.6%).

CONCLUSIONS

In EONS, PCT measurements at birth may initially be normal; a serial PCT measurement at 24h of age may be more helpful for an early diagnosis. During the first 24h of life PCT is a more sensitive marker of infection than C-reactive protein. Further studies are needed to confirm our findings.

Adjunct laboratory tests in the diagnosis of early-onset neonatal sepsis

Early-onset sepsis remains a major diagnostic problem in neonatal medicine. Definitive diagnosis depends on cultures of blood or other normally sterile body fluids. Abnormal hematological counts, acute-phase reactants, and inflammatory cytokines are neither sensitive nor specific, especially at the onset of illness. Combinations of measurements improve diagnostic test performance, but the optimal selection of analytes has not been determined. The best-established use of these laboratory tests is for retrospective determination that an infant was not infected, based on failure to mount an acute-phase response over the following 24 to 48 hours.

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

Procalcitonin, the prohormone of calcitonin, is a relatively new and innovative marker of bacterial infection that has multiple potential applications in the pediatric emergency department. In healthy individuals, circulating levels of procalcitonin are generally very low (<0.05 ng/mL), but in the setting of severe bacterial infection and sepsis, levels can increase by hundreds to thousands of fold within 4 to 6 hours. Although the exact physiologic function of procalcitonin has not been determined, the consistent response and rapid rise of this protein in the setting of severe bacterial infection make procalcitonin a very useful biomarker for invasive bacterial disease. In Europe, serum procalcitonin measurements are frequently used in the diagnosis and the management of patients in a variety of clinical settings. To date, the use of procalcitonin has been limited in the United States, but this valuable biomarker has many potential applications in both the pediatric emergency department and the intensive care unit. The intent of this article is to review the history of procalcitonin, describe the kinetics of the molecule in response to bacterial infection, describe the laboratory methods available for measuring procalcitonin, examine the main causes of procalcitonin elevation, and evaluate the potential applications of procalcitonin measurements in pediatric patients.

Procalcitonin in the early diagnosis of nosocomial sepsis in preterm neonates

AIM

To examine the diagnostic usefulness of procalcitonin (PCT), C-reactive protein and immature to total neutrophil ratio (I : T) in nosocomial sepsis among neonates treated in an intensive care unit.

METHODS

A retrospective analysis and comparison of diagnostic utility performed in preterm neonates using receiver operating characteristic curves for the diagnosis of culture-proven sepsis.

RESULTS

A total of 78 clinically suspected sepsis episodes in 73 newborns were analysed. The median values of PCT were: 0.56 ng/mL (interquartile range (IQR) 0.33-1.32) in group with aseptic blood culture (n = 15), 2.69 ng/mL (IQR 1.10-5.29) in Gram-positive (n = 47) and 9.36 ng/mL (IQR 3.11-39.35) in Gram-negative sepsis (n = 16). Only PCT values were significantly different (P < 0.01) among all groups. This was also true when correction for differences in blood withdrawal time was implemented. The positive and negative predictive values of PCT in the diagnosis of sepsis equalled 97.5% and 88.9%, respectively, for a cut-off value of 0.99 ng/mL. PCT was significantly better in diagnosis of sepsis than I : T (P = 0.03). No other significant differences in diagnostic efficacy were noted. The diagnostic efficacy was the highest for measurements made two or more hours since the onset of symptoms.

CONCLUSIONS

The PCT serum concentration is a valuable tool for early detection of nosocomial sepsis in infants. Highest levels of PCT were observed in Gram-negative infections.

Procalcitonin for the clinical laboratory: a review

Procalcitonin measurement has been claimed as a helpful marker in bacterial infection and sepsis. It has obtained FDA approval and is now widely marketed in the United States and Europe. This review summarises the current assays available, the evidence for its use and possible future applications of the assay.

Evaluation of procalcitonin for diagnosis of neonatal sepsis of vertical transmission

Background

The results of recent studies suggest the usefulness of PCT for early diagnosis of neonatal sepsis, with varying results. The aim of this prospective multicenter study was to determine the behavior of serum PCT concentrations in both uninfected and infected neonates, and to assess the value of this marker for diagnosis of neonatal sepsis of vertical transmission.

Methods

PCT was measured in 827 blood samples collected prospectively from 317 neonates admitted to 13 acute-care teaching hospitals in Spain over one year. Serum PCT concentrations were determined by a specific immunoluminometric assay. The diagnostic efficacy of PCT at birth and within 12–24 h and 36–48 h of life was evaluated calculating the sensitivity, specificity, and likelihood ratio of positive and negative results.

Results

169 asymptomatic newborns and 148 symptomatic newborns (confirmed vertical sepsis: 31, vertical clinical sepsis: 38, non-infectious diseases: 79) were studied. In asymptomatic neonates, PCT values at 12–24 h were significantly higher than at birth and at 36–48 h of life. Resuscitation at birth and chorioamnionitis were independently associated to PCT values. Neonates with confirmed vertical sepsis showed significantly higher PCT values than those with clinical sepsis. PCT thresholds for the diagnosis of sepsis were 0.55 ng/mL at birth (sensitivity 75.4%, specificity 72.3%); 4.7 ng/mL within 12–24 h of life (sensitivity 73.8%, specificity 80.8%); and 1.7 ng/mL within 36–48 h of life (sensitivity 77.6%, specificity 79.2%).

Conclusion

Serum PCT was moderately useful for the detection of sepsis of vertical transmission, and its reliability as a maker of bacterial infection requires specific cutoff values for each evaluation point over the first 48 h of life.

Procalcitonin is not sufficiently reliable to be the sole marker of neonatal sepsis of nosocomial origin

Background

It has recently been suggested that serum procalcitonin (PCT) is of value in the diagnosis of neonatal sepsis, with varying results. The aim of this prospective multicenter study was to assess the usefulness of PCT as a marker of neonatal sepsis of nosocomial origin.

Methods

One hundred infants aged between 4 and 28 days of life admitted to the Neonatology Services of 13 acute-care teaching hospitals in Spain over 1-year with clinical suspicion of neonatal sepsis of nosocomial origin were included in the study. Serum PCT concentrations were determined by a specific immunoluminometric assay. The reliability of PCT for the diagnosis of nosocomial neonatal sepsis at the time of suspicion of infection and at 12–24 h and 36–48 h after the onset of symptoms was calculated by receiver-operating characteristics (ROC) curves. The Youden's index (sensitivity + specificity - 1) was used for determination of optimal cutoff values of the diagnostic tests in the different postnatal periods. Sensitivity, specificity, and the likelihood ratio of a positive and negative result with the 95% confidence interval (CI) were calculated.

Results

The diagnosis of nosocomial sepsis was confirmed in 61 neonates. Serum PCT concentrations were significantly higher at initial suspicion and at 12–24 h and 36–48 h after the onset of symptoms in neonates with confirmed sepsis than in neonates with clinically suspected but not confirmed sepsis. Optimal PCT thresholds according to ROC curves were 0.59 ng/mL at the time of suspicion of sepsis (sensitivity 81.4%, specificity 80.6%); 1.34 ng/mL within 12–24 h of birth (sensitivity 73.7%, specificity 80.6%), and 0.69 ng/mL within 36–48 h of birth (sensitivity 86.5%, specificity 72.7%).

Conclusion

Serum PCT concentrations showed a moderate diagnostic reliability for the detection of nosocomial neonatal sepsis from the time of suspicion of infection. PCT is not sufficiently reliable to be the sole marker of sepsis, but would be useful as part of a full sepsis evaluation.

Procalcitonina para el diagnóstico de sepsis neonatal de origen nosocomial

BACKGROUND

Nosocomial sepsis is a major problem in neonatal units. Because the clinical signs are nonspecific, highly reliable diagnostic markers are required to guide diagnosis. The aim of this study was to evaluate the utility of procalcitonin (PCT) as a diagnostic marker for nosocomial neonatal sepsis, and to compare the results of PCT with those of the most widely used laboratory tests for sepsis.

PATIENTS AND METHODS

Twenty neonates with nosocomial sepsis and 20 controls aged 4-30 days were included in a prospective study performed in a neonatal intensive care unit. PCT, C-reactive protein (CRP), leukocyte count, and the immature-to-total neutrophil ratio (I/T ratio) were measured at onset of signs of infection. The sensitivity, specificity, and likelihood ratio for a positive (LR+) and a negative (LR-) result were calculated.

RESULTS

PCT, CRP, and the I/T ratio discriminated septic from nonseptic patients. Their areas under the ROC curve were 0.849, 0.880, and 0.884, respectively, with no statistically significant differences. Optimal cut-off values were: PCT > or = 0.65 ng/ml (sensitivity 85 %, specificity 80 %, LR 1 4.25, LR- 0.19), PCR > or = 5 .g/ml (sensitivity 80 %, specificity 95 %, LR 1 16, LR- 0.21), and I/T > or = 0.03 (sensitivity 90 %, specificity 75 %, LR 1 3.6, LR- 0.13).

CONCLUSIONS

PCT may be a useful marker for the diagnosis of nosocomial neonatal sepsis. Studies with larger samples are required to compare the accuracy of PCT with that of other markers of sepsis.

Procalcitonina para el diagnóstico de sepsis neonatal de transmisión vertical

OBJECTIVE

To evaluate procalcitonin (PCT) as a diagnostic marker of neonatal sepsis of vertical transmission and to compare the results of PCT with those of the most widely used laboratory tests for sepsis.

PATIENTS AND METHODS

A prospective study was conducted in 136 blood samples from 69 newborn infants admitted to a neonatal department. PCT, C-reactive protein (CRP), leukocyte count, and the immature-to-total neutrophil ratio (I/T ratio) were measured. The PCT reference range of controls from 0 to 72 hours of life was constructed, and the diagnostic efficiency of the tests was calculated, with their 95 % confidence intervals (95 % CI).

RESULTS

This study included 35 controls, 24 neonates with noninfectious disorders, and 10 neonates with sepsis (5 with culture-proven sepsis). PCT, CRP, and the I/T ratio discriminated septic from nonseptic patients. Their areas under the ROC curve were 0.696 (p = 0.009), 0.735 (p = 0.002), and 0.703 (p = 0.006), respectively, with no statistically significant differences. The accuracy of PCT, CRP, and leukocyte count improved after 24 hours of life with areas under the ROC curve of 0.813 (p = 0.007), 0.826 (p = 0.005), and 0.841 (p = 0.003), respectively. Overall, PCT detected vertically transmitted sepsis with a sensitivity of 68.4 % (95 % CI: 46.0 %-84.6 %), specificity of 82.4 % (95 % CI: 72.2 %-89.4 %), positive likelihood ratio of 3.89 (95 % CI: 2.18 %-6.96 %), and negative likelihood ratio of 0.38 (95 % CI: 0.19 %-0.76 %), similar to those of CRP.

CONCLUSIONS

PCT may be a useful marker for the diagnosis of vertically transmitted sepsis. Studies with larger sample sizes are required to establish the accuracy of PCT.

Immunologic markers in the neonatal period: diagnostic value and accuracy in infection

Diagnosis of early-onset neonatal infection has led to the development of several screening tests including C-reactive protein, a very commonly used marker, and cytokines (mainly interleukin-6 and -8), alone or in combination with C-reactive protein, based on the premise that their increases in response to infection may precede that of C-reactive protein. In recent years the search for diagnostic tests has turned to procalcitonin, a propeptide of calcitonin, which appears to be a promising marker of infection in newborn infants. Additionally, specific leukocyte cell surface antigens (mainly CD11b and CD64), detected by flow cytometry, are evaluated as markers of neonatal infection, since their expression on the cell membrane increases in substantial quantities after leukocyte activation by bacteria or their cellular products. This review aims to examine the role of these newly available immunologic indices and to assess their validity as diagnostic markers of infection during the neonatal period.

Procalcitonin as an early marker of infection in neonates and children

A child or neonate presenting with fever is a common medical problem. To differentiate between those with a severe bacterial infection and those with a localised bacterial or a viral infection can be a challenge. This review provides an overview of neonatal and paediatric studies that assess the use of procalcitonin as an early marker of bacterial infection. Procalcitonin is an excellent marker for severe, invasive bacterial infection in children. However, the use of procalcitonin in the diagnosis of neonatal bacterial infection is complicated, but if correctly used procalcitonin results in a higher specificity than C-reactive protein. In addition, procalcitonin has been shown to correlate with severity of disease (urinary tract infections and sepsis), and can therefore be used as a prognostic marker. Procalcitonin is therefore a useful additional tool for the diagnosis of bacterial disease in neonates and children.

Soluble L-selectin, a marker of immune activation, in neonatal infection

L-Selectin is an adhesion molecule shed from the surface of lymphocytes and granulocytes upon activation. Soluble L-selectin in the plasma can thus reflect immune activation and is elevated in several pathological states. Our objective was to evaluate plasma levels of L-selectin as an immune activation marker in neonates and to determine whether it can serve as a marker of infection, either neonatal or congenital, or if it is affected by the mode of delivery and obstetrical or perinatal complications. A solid-phase ELISA was used on 89 sera from neonates less than 2 days of age, according to the manufacturer's instructions. Levels of soluble L-selectin in the neonate were lower than those of older infants and children and comparable to the levels seen in adults. There was no difference between levels of soluble L-selectin of premature (median, 1172 ng/ml) and full-term babies (median, 1151 ng/ml) or between babies born via vaginal (median, 1233 ng/ml) or cesarean delivery (median, 1146 ng/ml). Conditions such as preeclampsia or administration of steroids to the mother did not affect the levels of L-selectin in the neonate. In contrast, the presence of maternal clinical chorioamnionitis resulted in an increase in levels of L-selectin in the neonate (median, 1377 vs 1072 ng/ml, p = 0.02), as did neonatal sepsis (median, 1331 vs 1149 ng/ml, p = 0.026). Soluble L-selectin, and thus immune activation level, is highest in neonates with neonatal infection and needs to be further evaluated as a surrogate marker for diagnosing sepsis in the neonate.

Procalcitonin and interleukin-6 in the diagnosis of early-onset sepsis of the neonate

The reliability of procalcitonin (PCT) and interleukin-6 (IL-6) was determined and compared with that of C-reactive protein (CRP) in the diagnosis of early-onset sepsis of the neonate within the first 12 h of life. ROC analysis of values of 41 neonates with blood-cultures-positive and clinical sepsis compared with those of 27 uninfected neonates revealed sensitivities for PCT (> or = 6 ng/mL), IL-6 (> or = 60 pg/mL), and CRP (> or = 2.5 mg/L) of 77%, 54%, and 69% and specificities of 91%, 100% and 96%, respectively. Sensitivity of CRP at > or = 8 mg/L was 49% (p = 0.012 compared to PCT).

CONCLUSION

PCT was the most sensitive diagnostic parameter in the diagnosis of early-onset sepsis within 12 h of life.

Pneumonia in term neonates: laboratory studies and duration of antibiotic therapy

OBJECTIVES

To compare 2 days of antibiotic therapy (AT) to 4 days of AT in neonates with pneumonia and to assess the usefulness of neutrophil values (NV), C-reactive protein (CRP), and procalcitonin (PCT) in this population.

DESIGN

The study population consisted of consecutive, eligible term neonates begun on AT for suspected pneumonia. Of 51 neonates, 26 qualified for randomization (14, 2-day group; 12, 4-day group). NV were obtained with the initial evaluation and 12 and 24 hours later. CRP and PCT were obtained 12 and 48 hours after the initial evaluation.

RESULTS

None of the 12 neonates in the 4-day group developed recurrent respiratory symptoms. Three of the 14 neonates randomized to the 2-day group had recurrence of symptoms, resulting in study termination. NV, CRP, and PCT were similar in the 2- and 4-day groups. In the three neonates who developed respiratory symptoms, all absolute total neutrophil values and five out of nine absolute total immature neutrophil values were abnormal. However, all immature:total neutrophil values were normal, and CRP was strikingly elevated in only one neonate; only one of six PCT values was abnormal. In a secondary analysis of all 51 study neonates, CRP and PCT did not provide additional benefit over NV in differentiating neonates with pneumonia.

CONCLUSIONS

Four days of AT appears to be adequate for selected term neonates with pneumonia; however, 2 days of AT appears to be inadequate for this population. Relative to NV, CRP and PCT appear to have a limited role.

Umbilical cord blood serum procalcitonin concentration in the diagnosis of early neonatal infection

OBJECTIVE

To evaluate serum procalcitonin concentration in umbilical cord blood for diagnosis of intrauterine bacterial infection.

MATERIALS AND METHODS

A prospective study was conducted between 2000 and 2001. Serum procalcitonin concentrations were evaluated in 187 umbilical cord blood samples. Five groups have been defined: controls A (n=37), full-term noninfected B1 (n=80) and infected neonates B2 (n=8), preterm noninfected C1 (n=38) and infected C2 (n=24) newborns. An immunoluminometric assay was used to determine procalcitonin concentration. The Mann-Whitney U-test and Spearman's correlation ratio were applied. The sensitivity and specificity, the positive and negative predictive values, and the area under receiver operating characteristic curves were calculated.

RESULTS

A statistically higher serum procalcitonin concentration was found in the preterm infected group (p<0.005; C2 vs A and C1).

CONCLUSION

Serum procalcitonin concentration in umbilical cord blood may be a useful parameter in the diagnosis of early neonatal infection.

Postnatal increase of procalcitonin in premature newborns is enhanced by chorioamnionitis and neonatal sepsis

BACKGROUND

To determine the influence of chorioamnionitis and neonatal sepsis on procalcitonin (PCT) levels in very-low-birth-weight (VLBW) infants within the first week of life.

DESIGN

PCT serum levels were measured in cord blood 1 h after delivery and on day 3 and day 7 of life. Chorioamnionitis and neonatal sepsis within the first week were monitored.

RESULTS

Chorioamnionitis was present in eight of 37 patients (21.6%). PCT on day 3 was increased in both the "No chorioamnionitis" (2.54 ng mL(-1), SEM 0.51) and "Chorioamnionitis" (6.96 ng mL(-1), SEM 2.93) groups of VLBW infants compared with the 1st hour values (0.45 and 0.58 ng mL(-1) SEM 0.07 and 0.11, respectively, P < 0.001) of the same patients. The postnatal gain was higher in the "Chorioamnionitis" group (P < 0.01). Neonatal sepsis was diagnosed (after exclusion) in 12 of 32 patients (37.5%). Mean values of maximum PCT in patients with and without sepsis were 8.41 ng mL(-1) (SEM 1.87) and 3.02 ng mL(-1) (SEM 1.38), respectively (P < 0.05). Sensitivity to sepsis of PCT, ratio of immature to total neutrophils (I : T), and C-reactive protein (CRP) were 75%, 50% and 25%, respectively.

CONCLUSIONS

In the group of VLBW infants the PCT level within 72 h of delivery was markedly increased in patients with chorioamnionitis. Compared with I : T and CRP, PCT appears to be a more sensitive marker of neonatal sepsis.

Procalcitonin as an acute phase marker

Procalcitonin is a 14-kDa protein encoded by the Calc-1 gene along with calcitonin and katacalcin. The function and regulation of this protein are quite different from those of the other gene products. Blood concentrations of procalcitonin are increased in systemic inflammation, especially when this is caused by bacterial infection. Studies of its behaviour in patients with bacterial sepsis have led to the proposal that it may be a useful marker of systemic bacterial infection, with greater specificity and sensitivity than acute phase proteins such as C-reactive protein.

Serum Procalcitonin Concentrations in Term Delivering Mothers and Their Healthy Offspring: A Longitudinal Study

Background: The reported sensitivities and specificities of procalcitonin (PCT) concentrations for the diagnosis of neonatal infection vary widely. A postnatal increase of PCT has been observed in healthy term newborns with a peak at ≈24 h of age, and many questions remain regarding maternal and perinatal factors that may influence the normal PCT kinetics during the immediate postnatal period.

Methods: We prospectively investigated the association between the serum PCT values obtained from 121 mothers at delivery and serum PCT in their healthy, term offspring at birth as well as at 24 and 48 h of age. We also analyzed whether obstetric and perinatal factors would alter maternal and neonatal PCT response.

Results: PCT concentrations in the babies at birth were significantly higher than in the mothers (P &lt;0.0001), with even larger differences at 24 and 48 h of age. None of the variables identified from maternal and perinatal histories had a significant effect on maternal PCT response. In the healthy neonate, the variables that significantly affected the concentration of PCT at birth were the mothers’ PCT (P &lt;0.01), maternal group B streptococcus colonization (P &lt;0.05), and rupture of membranes ≥18 h (P &lt;0.01). The coefficient of linear correlation between the mother’s PCT concentration and that of the baby at birth was 0.32 (P &lt;0.01). The only variable that significantly altered the PCT concentration at both 24 (P &lt;0.01) and 48 (P &lt;0.01) h of age was rupture of membranes ≥18 h. Nonetheless, the PCT response observed during the 48-h period after birth among healthy babies born to mothers with risk factors for infection was well below that reported previously among age-matched neonates with sepsis.

Conclusions: The postnatal increase of PCT observed in the healthy neonate with peak values at 24 h of age most likely represents endogenous synthesis. In estimating the sensitivities and specificities of PCT for diagnosis of sepsis throughout the initial 48 h of life, it is important to consider the normal PCT kinetics and the pattern(s) of PCT response in the healthy neonate.

Comparison of procalcitonin with interleukin 8, C-reactive protein and differential white blood cell count for the early diagnosis of bacterial infections in newborn infants

OBJECTIVE

To evaluate procalcitonin (PCT) as a test for early diagnosis of bacterial infections (BI) in newborn infants and to compare the results of PCT with those of interleukin 8 (IL-8), C-reactive protein (CRP) and differential white blood cell count.

STUDY DESIGN

PCT was prospectively measured along with IL-8, CRP and differential white blood cell counts and blood cultures in 197 newborn infants at the first suspicion of bacterial infection. PCT, IL-8, CRP and differential white blood cell counts were analyzed for sensitivity, specificity and positive and negative predictive values after receiver operating characteristic curve analysis for best thresholds. The kinetics of PCT was determined in infants with and without BI.

RESULTS

Forty-six infants were diagnosed clinically as having BI, of whom 9 had BI with positive blood cultures. At a cutoff value of 0.50 microg/l, PCT detected combined culture-proved and clinical BI with a sensitivity of 57% (95% confidence interval, 41%, 71%) and a specificity of 66% (95% confidence interval, 57%, 74%). The combination of IL-8 > or =70 ng/l and/or CRP >10 mg/l achieved a sensitivity of 91% (95% confidence interval, 79%, 98%) and a specificity of 73% (95% confidence interval, 64%, 81%). PCT values of infected and not infected infants tended to rise for 24 h after initial evaluation and then decreased.

CONCLUSION

The combination of IL-8 and CRP is more reliable than PCT as a test for early diagnosis of BI in newborn infants.