Procalcitonin as a marker of nosocomial infections in the neonatal intensive care unit

Diagnostic Value of Neutrophil to Lymphocyte Ratio and Mean Platelet Volume on Early Onset Neonatal Sepsis on Term Neonate

By setting out from increased neutrophil count, decreased lymphocyte count, and increased mean platelet volume (MPV), which is a result of the effect of inflammation on blood cells, we aimed to investigate whether neutrophil to lymphocyte ratio (NLP) and MPV can be used as an auxiliary parameter for the diagnosis of early-onset neonatal sepsis (EOS). This study was conducted by analyzing term neonates with EOS and physiological jaundice who were admitted to the neonatal intensive care unit of Izmir Katip Celebi University Ataturk Training and Research Hospital. A total of 63 neonate files were examined to include 30 term neonates with EOS, and 77 neonate files were examined to include 30 term neonates with physiological jaundice as a control group. NLR had an area under the curve (AUC) of 0.891 for prediction of EOS. At a cut-off level of 1.42, NLR had a likelihood ratio (LR) of 5.5, sensitivity of 88%, a specificity of 84%, a positive predictive value (PPV) of 84.6%, and a negative predictive value (NPV) of 87.5%. MPV had an AUC of 0.666 for the prediction of EOS and at a cut-off level of 9.3 fL, MPV had an LR of 1.23, sensitivity of 84%, a specificity of 32%, a PPV of 55.2%, and an NPV of 66.6%. In conclusion, this study provides evidence that NLR and MPV can be used in addition to conventional parameters in the diagnosis of EOS.

New Diagnostic Possibilities for Early Onset Neonatal Sepsis: Red Cell Distribution Width to Platelet Ratio

Aims: Red cell distribution width to platelet ratio (RPR) has been reported as a useful inflammatory marker and prognostic indicator of adult inflammatory diseases. In the present study, red cell distribution width (RDW) and RPR parameters, which are parts of a complete blood count analysis, were compared to the traditional C reactive protein (CRP) and procalcitonin (PCT) parameters to investigate the potential to predict early onset sepsis (EOS) in neonates with or without positive blood cultures. Methods: An observational, retrospective cohort study was conducted to evaluate newborns born in our hospital. Results: RDW, RPR, CRP, PCT, Immature to total neutrophil ratio (I/T), and white blood cell (WBC) counts were higher in suspected and proven EOS compared to control group. Conclusion: We believe that RPR may be used in diagnosis of early onset neonatal sepsis and may be a good alternative to other tools as a readily available biomarker.

Early Inflammatory Markers for the Diagnosis of Late-Onset Sepsis in Neonates: The Nosodiag Study

Background: Early diagnosis is essential to improve the treatment and prognosis of newborn infants with nosocomial bacterial infections. Although cytokines and procalcitonin (PCT) have been evaluated as early inflammatory markers, their diagnostic properties have rarely been compared. Objectives: This study evaluated and compared the ability of individual inflammatory markers available for clinician (PCT, semi-quantitative determination of IL-8) and of combinations of markers (CRPi plus IL-6 or quantitative or semi-quantitative determination of IL-8) to diagnose bacterial nosocomial infections in neonates. Methods: This prospective two-center study included neonates suspected of nosocomial infections from September 2008 to January 2012. Inflammatory markers were measured initially upon suspicion of nosocomial infection, and CRP was again measured 12-24 h later. Newborns were retrospectively classified into two groups: those who were infected (certainly or probably) and uninfected (certainly or probably). Results: The study included 130 infants of median gestational age 28 weeks (range, 24-41 weeks). Of these, 34 were classified as infected and 96 as uninfected. The sensitivity, specificity, positive and negative predictive values (PPV and NPV), and positive and negative likelihood ratios (LR+ and LR-) for PCT were 59.3% (95% confidence interval [CI], 38.8-77.6%), 78.5% (95% CI, 67.8-86.9%), 48.5% (95% CI, 30.8-66.5%), 84.9% (95% CI, 74.6-92.2%), 2.7 (95% CI, 1.6-4.9), and 0.5 (95% CI, 0.3-0.8), respectively. Semi-quantitative IL-8 had the highest specificity (92.19%; 95% CI, 82.70-97.41%), PPV (72.22%; 95% CI, 46.52-90.30%) and LR+ (6.17, 95% CI, 2.67-28.44), but had low specificity (48.15%; 95% CI, 28.67-68.05%). Of all markers tested, the combination of IL-6 and CRPi had the highest sensitivity (78.12%; 95% CI, 60.03-90.72%), NPV (91.3%; 95% CI, 82.38-96.32%) and LR- (0.29; 95% CI, 0.12-0.49). The combination of IL-6 and CRPi had a higher area under the curve than PCT, but with borderline significance (p = 0.055). Conclusions: The combination of IL-6 and CRPi was superior to other methods, including PCT, for the early diagnosis of nosocomial infection in neonates, but was not sufficient for sole use. The semi-quantitative determination of IL-8 had good diagnostic properties but its sensitivity was too low for use in clinical practice.

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.

Serum bone alkaline phosphatase in assessing illness severity of infected neonates in the neonatal intensive care unit

Background: Infections can influence bone metabolism of neonates, which may lead to changes in some bone metabolism biomarkers. The purpose of this study was to determine whether serum bone alkaline phosphatase (BALP), osteocalcin (OC) and beta carboxy-terminal peptide of type I collagen (CTX), as specific biomarkers of bone metabolism, can be used to assess the severity of neonatal infections.

Methods: Sixty-three neonates in the NICU were enrolled in this study. The neonates were divided into infected group (n=33) and non-infected group (n=30). The scores for neonatal acute physiology-perinatal extension II (SNAPPE-II) were calculated and interleukin-6 (IL-6), procalcitonin (PCT), BALP, OC and CTX were measured among the neonates with or without infections, and among the infected neonates before and after treatment.

Results: The serum BALP levels were lower in the infected group than that in the non-infected group (p<0.01). The serum BALP levels increased markedly in the infected neonates after treatment (p<0.01). The serum BALP levels were also inversely correlated with SNAPPE-II of infected neonates before and after treatment (r=-0.56, p<0.05; r=-0.37, p<0.05, respectively). In infected neonates, the differences between serum BALP levels before and after treatment were inversely correlated with those of IL-6 levels (p<0.05). There were no significant changes in the OC, CTX and PCT levels in the infected or non-infected group before and after treatment.

Conclusion: Our data suggest that serum BALP level might be used as a marker for assessing the severity of illness in infected neonates.

Concentrations of procalcitonin and C-reactive protein, white blood cell count, and the immature-to-total neutrophil ratio in the blood of neonates with nosocomial infections: Gram-negative bacilli vs coagulase-negative staphylococci

This study was undertaken to determine whether concentrations of procalcitonin in the blood of neonates with nosocomial infections depend on the type of pathogen. Qualification for the study group was based on the clinical signs of infection. We found that infections with Gram-positive (chiefly coagulase-negative staphylococci) and Gram-negative bacteria are accompanied by elevated concentrations of procalcitonin. In the case of Gram-positive bacteria, other laboratory signs of infection studied by us (concentration of C-reactive protein, white blood cell count, immature-to-total neutrophil ratio) were not discriminatory, confirming the diagnostic usefulness of procalcitonin measurements in nosocomial infections of the neonate with Gram-negative or Gram-positive bacteria.

Biomarkers for pediatric sepsis and septic shock

Sepsis is a clinical syndrome defined by physiologic changes indicative of systemic inflammation, which are likely attributable to documented or suspected infection. Septic shock is the progression of those physiologic changes to the extent that delivery of oxygen and metabolic substrate to tissues is compromised. Biomarkers have the potential to diagnose, monitor, stratify and predict outcome in these syndromes. C-reactive protein is elevated in inflammatory and infectious conditions and has long been used as a biomarker indicating infection. Procalcitonin has more recently been shown to better distinguish infection from inflammation. Newer candidate biomarkers for infection include IL-18 and CD64. Lactate facilitates the diagnosis of septic shock and the monitoring of its progression. Multiple stratification biomarkers based on genome-wide expression profiling are under active investigation and present exciting future possibilities.

Comparison of serum amyloid A concentrations with those of C-reactive protein and procalcitonin in diagnosis and follow-up of neonatal sepsis in premature infants

OBJECTIVE

The purpose of this study was to determine the role of serum amyloid A (SAA) in diagnosis of neonatal sepsis and evaluation of clinical response to antibiotic therapy. We also aimed to compare the efficiency of SAA with that of C-reactive protein (CRP) and procalcitonin (PCT) in diagnosis and follow-up of neonatal sepsis in preterm infants.

STUDY DESIGN

A total of 163 infants were enrolled in this prospective study. The infants were classified into four groups: group 1 (high probable sepsis), group 2 (probable sepsis), group 3 (possible sepsis) and group 4 (no sepsis, control group). Blood samples for whole blood count, CRP, PCT, SAA and culture were obtained before initiating antibiotic treatment. This procedure was repeated three times at 48 h, 7 and 10 days.

RESULT

Initial CRP, PCT and SAA levels were found to be positive in 73.2, 75.6 and 77.2% of all infants, respectively. Sensitivities of CRP, PCT and SAA at 0 h were 72.3, 74.8 and 76.4%, respectively. Although it was not statistically significant, SAA was found to be more sensitive than CRP and PCT in diagnosis of neonatal sepsis. The area under the curve (AUC) for CRP, PCT and SAA at 0 h were 0.870, 0.870 and 0.875, respectively. Although the AUC for SAA at 0 h was higher than PCT and CRP, the difference was not statistically significant.

CONCLUSION

SAA is an accurate and reliable marker for diagnosis and follow-up of neonatal sepsis. It is especially useful at the onset of inflammation for rapid diagnosis of neonatal sepsis and can be safely and accurately used in combination with other sepsis markers such as CRP and PCT in diagnosis and follow-up of neonatal sepsis in preterm infants.

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.