Platelets in pediatric and neonatal sepsis: novel mediators of the inflammatory cascade

Diagnosis and Management of Neonatal Bacterial Sepsis: Current Challenges and Future Perspectives

Sepsis remains the second cause of death among neonates after the pathological consequences of extreme prematurity. In this review we summarized knowledge about pathogens causing early-onset sepsis (EOS) and late-onset sepsis (LOS), the role of perinatal risk factors in determining the EOS risk, and the tools used to reduce unnecessary antibiotics. New molecular assays could improve the accuracy of standard blood cultures, providing the opportunity for a quick and sensitive tool. Different sepsis criteria and biomarkers are available to date, but further research is needed to guide the use of antibiotics according to these tools. Beyond the historical antibiotic regimens in EOS and LOS episodes, antibiotics should be based on the local flora and promptly modulated if specific pathogens are identified. The possibility of an antibiotic lock therapy for central venous catheters should be further investigated. In the near future, artificial intelligence could help us to personalize treatments and reduce the increasing trend of multidrug-resistant bacteria.

Judicious Transfusion of Platelets Among Neonates: A Systematic Review

In newborns, especially premature babies, there is a high association between thrombocytopenia and bleeding, particularly intraventricular hemorrhage, which may be due to immaturity. It was usual clinical practice that neonates should be transfused with higher platelet counts than older children or adults to reduce their risk of bleeding. However, after keen observations, we noticed that bleeding and mortality were more common in newborns who received more platelet transfusions. The mechanisms underlying the adverse effects of platelet transfusions in neonates may be due to higher antigenicity and immunological factors. We know that neonatal platelets are hyporeactive; this hyporeactivity is balanced by factors in the neonatal blood that promote coagulation, such as increased hematocrit, von Willebrand factor, and fibrinogen, which, on balance, leads to normal primary neonatal hemostasis. Platelets are very similar to adults in number, but functional capabilities were less, and for the reasons mentioned above, particularly bleeding time was short. Theologically, neonatal platelet lifespan was high to compensate for less production. We started this review because we observed that many babies were not having bleeding symptoms in some instances of severe thrombocytopenia. Many well-active babies are receiving unnecessary transfusions, as human blood is precious, and many young neonatologists are going on protocol-based excessive transfusions. This stimulated us to write a review.

Markers of platelet activation foR identification of late onset sEpsis in infaNTs: PARENT study protocol

BACKGROUND

Newborns are at high risk of sepsis. At present there is no definitive "rule in" blood test for sepsis at the point of clinical concern. A positive blood culture remains the gold standard test for neonatal sepsis, however laboratory markers that correlate prospectively with culture positive sepsis could aid clinicians in making decisions regarding administration of empiric antibiotic therapies.

METHODS

This multi-site, prospective observational study will take place in two neonatal intensive care units (National Maternity Hospital and Rotunda Hospital, Dublin). Neonates born at less than 34 weeks will be enroled and informed consent obtained prior to late onset sepsis work up. If at any point subsequently during their neonatal intensive care stay they develop signs and symptoms of possible sepsis requiring blood culture, an additional sodium citrate sample will be obtained. Infants will be categorised into three groups as follows: (i) culture positive sepsis, (ii) culture negative sepsis where an infant receives 5 days of antibiotics (iii) non sepsis. Our primary outcome is to establish if differential platelet/endothelial activation can prospectively identify neonatal culture positive late onset sepsis.

TRIAL REGISTRATION NUMBER

NCT05530330 IMPACT: Preterm infants are a high risk group for the development of sepsis which is a major cause of mortality in this population. Platelets have been associated with host response to invasive bacterial infections both in animal models and translational work. A positive blood culture is the gold standard test for neonatal sepsis but can be unreliable due to limited blood sampling in the very low birth weight population. This study hopes to establish if platelet/endothelial associated plasma proteins can prospectively identify late onset neonatal sepsis.

Platelet distribution width as an useful indicator of influenza severity in children

PURPOSE

The present study aims to investigate the potential of platelet distribution width as an useful parameter to assess the severity of influenza in children.

METHODS

Baseline characteristics and laboratory results were collected and analyzed. Receiver operating characteristic (ROC) curve analysis was used to joint detection of inflammatory markers for influenza positive children, and the scatter-dot plots were used to compare the differences between severe and non-severe group.

RESULTS

Influenza B positive children had more bronchitis and pneumonia (P < 0.05), influenza A infected children had more other serious symptoms (P = 0.007). Neutrophil count, lymphocyte count, neutrophil-to-lymphocyte ratio (NLR), and platelet parameters performed differently among < 4 years and ≥ 4 years children with influenza. Combined detection of platelet parameters and other indicators could better separate healthy children from influenza infected children than single indicator detection. The levels of platelet distribution width of children with severe influenza (A and B) infection was significantly dropped, compared with non-severe group (P < 0.05).

CONCLUSIONS

Platelet distribution width could be a very useful and economic indicator in distinction and severity assessment for children with influenza.

Clinical Value of Laboratory Biomarkers for the Diagnosis and Early Identification of Culture-Positive Sepsis in Neonates

Background

Neonatal sepsis (NS) is an important cause of mortality and morbidity in newborn infants. However, early diagnosis of proven sepsis (culture-positive sepsis) is difficult. We aimed to define the best combination of biomarkers to diagnose the onset of neonatal sepsis, distinguish culture-positive neonatal sepsis and predict the time of confirmation of neonatal sepsis.

Methods

This retrospective cohort study was conducted from January 2016 to December 2020. Clinical characteristics and laboratory results were collected from the electronic medical records. Hematology profiles and biochemical indices were obtained upon hospital admission. Multivariate logistic regression analysis was used to evaluate the risk factors and construct a nomogram. The performance of the nomogram was evaluated by receiver operating characteristic (ROC) curve and decision curve analysis (DCA). Multivariable linear regression was used to identify the association between admission-to-diagnosis interval (ADI) and correlated variables.

Results

Overall, 148 infants with neonatal sepsis (67 culture positive sepsis and 81 culture negative sepsis) and 150 controls were included. C-reactive protein (CRP) (p<0.001), platelets (PLT) (p=0.011), urea nitrogen (BUN) (p=0.001) and conjugated bilirubin (BC) (p=0.007) were independent risk factors for neonatal sepsis. The diagnostic nomogram based on CRP, PLT, BUN and BC showed excellent diagnostic accuracy for neonatal sepsis (AUC=0.928). The nomogram based on red blood cell distribution width (RDW) and mean platelet volume (MPV) was efficient in distinguishing proven neonatal sepsis from clinical sepsis, with an AUC of 0.700 in the training group and 0.689 in the validation group. Decision curve analysis (DCA) showed that the nomogram had good clinical utility. Multivariable analysis revealed gestational age, CRP, and MPV were significantly associated with admission-to-diagnosis interval in culture-positive sepsis (p < 0.001).

Conclusion

Different combinations biomarkers were performant to diagnose the onset of neonatal sepsis, distinguish culture-positive neonatal sepsis, predict the time of confirmation, and aid in individual therapy.

Prognostic value of blood inflammatory parameters for predicting mortality in neonates with sepsis

BACKGROUND

Neonatal sepsis is a major cause of morbidity and mortality in neonates. The diagnosis of neonatal sepsis has been widely explored using blood inflammatory parameters. However, few researches have focused on the predictive significance of blood inflammation parameters for predicting mortality. This study aimed to evaluate the prognostic value of blood inflammatory parameters, including white blood cell (WBC), neutrophil, lymphocyte, monocyte, platelet and C-reactive protein (CRP) for predicting mortality in neonates with sepsis.

METHODS

Neonates with culture-proven sepsis were enrolled in this study. The clinical characteristics and levels of white blood cell, neutrophil, lymphocyte, monocyte, platelet and CRP were recorded. The receiver-operating characteristic (ROC) curve was applied to calculate the area under the curve (AUC) and determine the optimal cutoff values. Multivariable Cox regression model was used to evaluate the independent prognostic significance of variables. Kaplan-Meier curve was used to assess survival.

RESULTS

A total of 188 neonates with culture-proven sepsis were included for analysis. The 7-day mortality rate was 11.2 % (21/188) and the 28-day mortality rate was 13.8 % (26/188). The levels of white blood cell, neutrophil, monocyte and platelet in non-survivors were lower than those in survivors (P < 0.05). Platelet yielded higher AUC values than other parameters for predicting mortality with the best cutoff value of 132 × 109/L, followed by WBC with the optimal cutoff value of 6.15 × 109/L. Multivariable Cox regression analysis showed platelet and WBC were independent prognostic factors for predicting mortality. Low platelet group showed lower survival according to Kaplan-Meier method.

CONCLUSIONS

In conclusion, the levels of platelet and WBC on the day of sepsis onset are valuable indicators for predicting mortality in neonates with sepsis.

A Global Assessment of Coagulation Profile and a Novel Insight into Adamts-13 Implication in Neonatal Sepsis

Neonatal sepsis is a life-threatening condition associated with significant morbidity and mortality. Sepsis-induced coagulopathy is a well-recognized entity, signifying the strong cross-talk between inflammation and coagulation. The aim of the present study was to compare the coagulation profile between the acute phase of sepsis and recovery in term and preterm neonates. Additional comparisons to healthy neonates were undertaken. Levels of clotting, anti-clotting factors and ADAMTS-13 (A disintegrin and metalloprotease with thrombospondin type-1 motives), the cleaving protein of von Willebrand factor (VWF), were measured in 16 term and preterm neonates in the acute phase of infection and following recovery, as well as in 18 healthy neonates. Clotting times were prolonged, while levels of particular clotting factors were lower in the acute phase of infection compared to controls and recovery. On the other hand, levels of fibrinogen, factor VIII (FVIII) and VWF were significantly higher in the acute phase in comparison to controls and recovery, while they remained persistently higher in the infection group compared to controls. In regard to the anticlotting mechanism, a clear suppression was observed in septic neonates. ADAMTS-13 levels were significantly lower in the acute phase of infection in comparison to controls and recovery (p = 0.015 and 0.004, respectively), while a trend toward superimposed normalization was demonstrated post infection, as higher ADAMTS-13 levels were measured in recovered neonates compared to controls (p = 0.002). The coagulation profile is considerably deranged in neonatal sepsis. ADAMTS-13 deficiency in septic neonates is a novel finding with promising future implications, as ADAMTS-13 substitution may serve as a useful therapeutic option in neonatal sepsis, prompting further investigation in future studies.

Platelet role in the prediction of MIS-C severity

Introduction

Multisystem inflammatory syndrome in children (MIS-C) has been reported as one of the cytokine storm syndromes associated with COVID-19. Despite the several proposed diagnostic criteria, MIS-C remains a diagnostic and clinical challenge. Recent studies have demonstrated that platelets (PLTs) play a crucial role in COVID-19 infection and its prognosis. This study aimed to investigate the clinical importance of PLT count and PLT indices in predicting MIS-C severity in children.

Patients and methods

We conducted a retrospective single-center study at our university hospital. A total of 43 patients diagnosed with MIS-C during a 2-year period (from October 2020 to October 2022) were included in the study. MIS-C severity was evaluated according to the composite severity score.

Results

Half of the patients were treated in the pediatric intensive care unit. No single clinical sign was associated with a severe condition, except for shock (p = 0.041). All the routine biomarkers, such as complete blood count (CBC) and C-reactive protein (CRP), used for MIS-C diagnosis were significant in predicting MIS-C severity. Single PLT parameters, such as mean PLT volume, plateletcrit, or PLT distribution width, did not differ between the severity groups. However, we found that a combination of PLT count and the previously mentioned PLT indices had the potential to predict MIS-C severity.

Conclusions

Our study emphasizes the importance of PLT in MIS-C pathogenesis and severity. It revealed that together with routine biomarkers (e.g., CBC and CRP), it could highly improve the prediction of MIS-C severity.

Group B Streptococcus Early-Onset Disease: New Preventive and Diagnostic Tools to Decrease the Burden of Antibiotic Use

The difficulty in recognizing early-onset neonatal sepsis (EONS) in a timely manner due to non-specific symptoms and the limitations of diagnostic tests, combined with the risk of serious consequences if EONS is not treated in a timely manner, has resulted in a low threshold for starting empirical antibiotic treatment. New guideline strategies, such as the neonatal sepsis calculator, have been proven to reduce the antibiotic burden related to EONS, but lack sensitivity for detecting EONS. In this review, the potential of novel, targeted preventive and diagnostic methods for EONS is discussed from three different perspectives: maternal, umbilical cord and newborn perspectives. Promising strategies from the maternal perspective include Group B Streptococcus (GBS) prevention, exploring the virulence factors of GBS, maternal immunization and antepartum biomarkers. The diagnostic methods obtained from the umbilical cord are preliminary but promising. Finally, promising fields from the newborn perspective include biomarkers, new microbiological techniques and clinical prediction and monitoring strategies. Consensus on the definition of EONS and the standardization of research on novel diagnostic biomarkers are crucial for future implementation and to reduce current antibiotic overexposure in newborns.

Survey of transfusion practices in preterm infants in Europe

BACKGROUND

Preterm infants commonly receive red blood cell (RBC), platelet and fresh frozen plasma (FFP) transfusions. The aim of this Neonatal Transfusion Network survey was to describe current transfusion practices in Europe and to compare our findings to three recent randomised controlled trials to understand how clinical practice relates to the trial data.

METHODS

From October to December 2020, we performed an online survey among 597 neonatal intensive care units (NICUs) caring for infants with a gestational age (GA) of <32 weeks in 18 European countries.

RESULTS

Responses from 343 NICUs (response rate: 57%) are presented and showed substantial variation in clinical practice. For RBC transfusions, 70% of NICUs transfused at thresholds above the restrictive thresholds tested in the recent trials and 22% below the restrictive thresholds. For platelet transfusions, 57% of NICUs transfused at platelet count thresholds above 25×10⁹/L in non-bleeding infants of GA of <28 weeks, while the 25×10⁹/L threshold was associated with a lower risk of harm in a recent trial. FFP transfusions were administered for coagulopathy without active bleeding in 39% and for hypotension in 25% of NICUs. Transfusion volume, duration and rate varied by factors up to several folds between NICUs.

CONCLUSIONS

Transfusion thresholds and aspects of administration vary widely across European NICUs. In general, transfusion thresholds used tend to be more liberal compared with data from recent trials supporting the use of more restrictive thresholds. Further research is needed to identify the barriers and enablers to incorporation of recent trial findings into neonatal transfusion practice.

Economic and Diagnostic Biomarker Tests of Neonatal Sepsis: A Prospective Study from a Tertiary Care Hospital in a Low-Income Country

Background. Neonatal sepsis is a leading cause of morbidity and mortality in low-and middle-income countries (LMICs). There are several sophisticated biomarkers; however, they are still insufficient in precision. In this perspective, our study aims to search for a pragmatic diagnostic biomarker in the age category. Methods. A cross-sectional study was conducted over six months(April-September 2018). All neonates with a diagnosis of probable sepsis were included. Logistic regression analysis of demographic variables was done to elucidate any association with confirmed sepsis cases. The median with interquartile range (IQR)] and mean with standard deviation (SD) were calculated, and then compared. The area under the receiver operating characteristic curve (AUROC) of the commonly opted biomarker tests [distribution width of red blood cells (RDW) and platelets(PDW), mean platelet volume(MPV), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR)] was compared to the culture-confirmed case. Results. Of the 171 suspected sepsis subjects, we discovered a significant burden of newborn sepsis, with 18.7% of cases being culture-confirmed. 66 Early-onset sepsis(EOS) and 105 Late-onset sepsis(LOS) probable sepsis cases were enrolled. A higher incidence was revealed among male infants 24(14%) compared to females 8(4.7%). On logistic regression analysis, preterm birth [odds ratio (OR): 10.9, 95% confidence interval (CI): 4.5-26.9] and low birth weight (OR: 6.5, 95% CI: 2.4-17.9) were significantly associated. Coagulase-negative Staphylococcus aureus (CoNS) (n =6) among gram-positive, and Pseudomonas aeruginosa (n =6) was among gram-negative, were the leading etiologies. Escherichia coli (n =3) was the predominant bacteria in EOS subjects, while Pseudomonas aeruginosa (n =6) among LOS. Median interquartile range(IQR): platelet count 144.5(99-192), red cell distribution width 18(16.9-20), CRP 6(3-18.3); and mean ± SD: MPV (11.7 ± 1.7); PDW (15.2 ± 3.5) were attained, among confirmed cases. The AUROC, of biomarker tests was attained in the order: PDW(0.86) > MPV(0.81) > RDW(0.76) > CRP(0.67) > ESR(0.59); similarly, the cut-off order was >11.2, >10.4, >16.8, >2.9, >4.5, respectively. Conclusions. Our finding shows an increment in the width and volume of RBCand platelet: RDW, MPV, and PDW have a diagnostic role in neonatal sepsis.

Preliminary Study on the Host Response to Bivalent and Monovalent Autogenous Vaccines against Mycoplasma agalactiae in Dairy Sheep

In Italy, dairy sheep farming represents a vital agro-industry sector, but it is still challenged by contagious agalactia (CA), which is endemic there, and vaccination is the most economical and sustainable tool for control. This study aimed to evaluate the combined Mycoplasma agalactiae (Ma)-Staphylococcus aureus (Sa) vaccine (Ma-Sa) against the Ma monovalent vaccine in ewes. Twelve primiparous Ma-free ewes were randomly grouped into three equal groups: first, the control group injected with placebo, second, the group vaccinated with the Ma monovalent vaccine, and third, the group vaccinated with Ma-Sa combined vaccine, with two S/C doses at 45-day intervals. The animals were examined for serological, hematological, and somatic cell count (SCC) changes for 17 successive weeks. A significant increase in anti-Ma antibody mean titers, leukocytes, and platelets was observed in the vaccinated animals, with the highest values in those who received the combined vaccine. Neutrophils were high only in the animals who received the combined vaccine. SCC was lower in the vaccinated animals during the first six weeks. This study concludes that the combined Ma-Sa vaccines enhance immune response and potentiate its efficacy against Ma. This improvement might be attributed to the sensitization/activation effect of S. aureus on platelets, which are recoded to act as a key regulator for the coordination of all components of the innate immune system. Even though this study included a small number of animals, its findings about the potentialities of this inactivated vaccine in the control of CA are strongly encouraging. Further confirmation might be needed through additional replicates and a challenge study is needed before proceeding with widespread use.

Effect of platelet count and platelet transfusion on fever duration in patients with febrile neutropenia

Platelets play a role in hemostasis, thrombosis, and vascular integrity. They also play a major role in the development of inflammation and the activation of immune responses. They have phagocytic activity, stimulate the secretion of immune modulators, and activate other immune cells, which results in platelet-neutrophil aggregation, platelet-induced neutrophil degranulation, and the formation of neutrophil extracellular traps. Data on 124 febrile neutropenia attacks were retrospectively examined. Patients' age, sex, diagnosis, and relapse history were obtained. The complete blood count levels on the first and last febrile day of the febrile neutropenia attacks, duration of fever, and number, type, and timing of thrombocyte suspension transfusions were recorded. The patients were divided into three groups according to the day of fever when the platelet suspension was administered (1 day, 2-3 days, and >3 days); the duration of fever was compared between the three groups. The fever duration of those who were transfused with platelet suspension on the first day of fever was found to be significantly shorter (p = 0.03 and p < 0.001, respectively). When treating a patient with febrile neutropenia, if thrombocyte suspension transfusion is indicated, transfusing thrombocytes in the first days of fever shortens the fever duration and improves the prognosis of febrile neutropenia attack, supporting the hypothesis that not only neutrophils but also platelets may play a role in fighting against microorganisms.

Paediatric and neonatal sepsis and inflammation

Sepsis has a huge impact on global mortality and has been declared as a priority by the World Health organisation the WHO.1 Children have a high incidence of sepsis especially in the neonatal with an estimated 3 million babies affected worldwide and mortality ranges from 11 to 19%.2 In addition, long-term neurodevelopmental outcomes are affected but this is largely unquantified. However, challenges remain in the early recognition, diagnosis and standardised management of sepsis. This series on Sepsis and inflammation in children reviews the conundrums of diagnostic criteria, biomarkers, management and future strategies to improve outcomes.