An Immunological Perspective on Neonatal Sepsis

Late-onset sepsis in newborns caused by Bacillus Cereus: a case report and literature review

Bacillus cereus is a bacterium capable of causing late-onset neonatal sepsis. By analyzing 11 cases, this study investigates the diagnosis, treatment, and prognosis of Bacillus cereus infections, aiming to provide insights into clinical diagnosis and therapy. The study scrutinized 11 instances of late-onset neonatal sepsis, including two fatalities attributable to Bacillus cereus, one accompanied by cerebral hemorrhage. An examination and analysis of these cases' symptoms, signs, laboratory tests, and treatment processes, along with a review of related literature from 2010 to 2020, revealed a high mortality rate of 41.38% in non-gastrointestinal infections caused by Bacillus cereus. Our findings underscore the critical importance of rapid diagnosis and effective antimicrobial therapy in reducing mortality rates. Once the source of infection is identified, implementing effective infection control measures is essential.

γδ T cell profiling in a cohort of preterm infants reveals elevated frequencies of CD83+ γδ T cells in sepsis

Preterm infants are at high risk of developing neonatal sepsis. γδ T cells are thought to be an important set of effector cells in neonates. Here, γδ T cells were investigated in a longitudinal cohort of preterm neonates using next-generation sequencing, flow cytometry, and functional assays. During the first year of life, the Vγ9Vδ2 T cell subset showed dynamic phenotypic changes and elevated levels of fetal-derived Vγ9Vδ2 T cells were evident in infants with sepsis. Single-cell transcriptomics identified HLA-DRhiCD83+ γδ T cells in neonatal sepsis, which expressed genes related to antigen presentation. In vitro assays showed that CD83 was expressed on activated Vγ9Vδ2 T cells in preterm and term neonates, but not in adults. In contrast, activation of adult Vγ9Vδ2 T cells enhanced CD86 expression, which was presumably the key receptor to induce CD4 T cell proliferation. Together, we provide a map of the maturation of γδ T cells after preterm birth and highlight their phenotypic diversity in infections.

Neonatal innate immunity response in invasive candidiasis

Infections caused by Candida spp. are frequent in critically hospitalized patients, especially among premature neonates, representing one of the most common healthcare-related infections. Although there is considerable production of current knowledge about the mechanisms of immune response, aspects involved in the newborn's innate defense are not fully understood. The aim of this study was to describe the innate immune mechanisms involved in the defense of neonates against invasive candidiasis. This is an integrative literature review from the Scopus, Scifinder, Medline, Web of Science databases and the electronic libraries ScienceDirect and Scielo, in the period between 2002 and 2020, with rescue based on primary descriptor Immunity Innate plus secondary descriptors Candidiasis Invasive AND Infant Newborn. We have observed the involvement of various mechanisms in the neonatal response against invasive candidiasis, including the recognition, signaling, recruitment, and initiation of an effective immune response. These mechanisms encompass the presence of antimicrobial peptides, phagocytosis, synthesis of reactive oxygen species, inflammatory mediators, and complex cell signaling systems mediated by Pattern Recognition Receptors (PRRs). With this study, it is expected to contribute to the expansion of knowledge about the immunological mechanisms involved in the innate immune response of the newborn against disseminated infections caused by Candida species, and in the same sense, highlight the importance of this knowledge as a reflex in the decrease in mortality in the neonatal period.

Prussian Blue Analogues-Derived Molecularly Imprinted Nanozyme Array for Septicemia Detection

Septicemia, a severe bacterial infection, poses significant risks to human health. Early detection of septicemia by tracking specific biomarkers is crucial for a timely intervention. Herein, we developed a molecularly imprinted (MI) TiO2-Fe-CeO2 nanozyme array derived from Ce[Fe(CN)6] Prussian blue analogues (PBA), specifically targeting valine, leucine, and isoleucine, as potential indicators of septicemia. The synthesized nanozyme arrays were thoroughly characterized using various analytical techniques, including Fourier transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscope, and energy-dispersive X-ray. The results confirmed their desirable physical and chemical properties, indicating their suitability for the oxidation of 3,3',5,5'-tetramethylbenzidine serving as a colorimetric probe in the presence of a persulfate oxidizing agent, further highlighting the potential of these arrays for sensitive and accurate detection applications. The MITiO2 shell selectively captures valine, leucine, and isoleucine, partially blocking the cavities for substrate access and thereby hindering the catalyzed TMB chromogenic reaction. The nanozyme array demonstrated excellent performance with linear detection ranges of 5 μM to 1 mM, 10-450 μM, and 10-450 μM for valine, leucine, and isoleucine, respectively. Notably, the corresponding limit of detection values were 0.69, 1.46, and 2.76 μM, respectively. The colorimetric assay exhibited outstanding selectivity, reproducibility, and performance in the detection of analytes in blood samples, including C-reactive protein at a concentration of 61 mg/L, procalcitonin at 870 ng/dL, and the presence of Pseudomonas aeruginosa bacteria. The utilization of Ce[Fe(CN)6]-derived MITiO2-Fe-CeO2 nanozyme arrays holds considerable potential in the field of septicemia detection. This approach offers a sensitive and specific method for early diagnosis and intervention, thereby contributing to improved patient outcomes.

Clinical Impact of Supplementation with Pasteurized Donor Human Milk by High-Temperature Short-Time Method versus Holder Method in Extremely Low Birth Weight Infants: A Multicentre Randomized Controlled Trial

Nosocomial infections are a frequent and serious problem in extremely low birth weight (ELBW) infants. Donor human milk (DHM) is the best alternative for feeding these babies when mother's own milk (MOM) is not available. Recently, a patented prototype of a High-Temperature Short-Time (HTST) pasteurizer adapted to a human milk bank setting showed a lesser impact on immunologic components. We designed a multicentre randomized controlled trial that investigates whether, in ELBW infants with an insufficient MOM supply, the administration of HTST pasteurized DHM reduces the incidence of confirmed catheter-associated sepsis compared to DHM pasteurized with the Holder method. From birth until 34 weeks postmenstrual age, patients included in the study received DHM, as a supplement, pasteurized by the Holder or HTST method. A total of 213 patients were randomized; 79 (HTST group) and 81 (Holder group) were included in the analysis. We found no difference in the frequency of nosocomial sepsis between the patients of the two methods-41.8% (33/79) of HTST group patients versus 45.7% (37/81) of Holder group patients, relative risk 0.91 (0.64-1.3), p = 0.62. In conclusion, when MOM is not available, supplementing during admission with DHM pasteurized by the HTST versus Holder method might not have an impact on the incidence of catheter-associated sepsis.

Life-threatening infections in human newborns: Reconciling age-specific vulnerability and interindividual variability

In humans, the interindividual variability of clinical outcome following exposure to a microorganism is immense, ranging from silent infection to life-threatening disease. Age-specific immune responses partially account for the high incidence of infection during the first 28 days of life and the related high mortality at population level. However, the occurrence of life-threatening disease in individual newborns remains unexplained. By contrast, inborn errors of immunity and their immune phenocopies are increasingly being discovered in children and adults with life-threatening viral, bacterial, mycobacterial and fungal infections. There is a need for convergence between the fields of neonatal immunology, with its in-depth population-wide characterization of newborn-specific immune responses, and clinical immunology, with its investigations of infections in patients at the cellular and molecular levels, to facilitate identification of the mechanisms of susceptibility to infection in individual newborns and the design of novel preventive and therapeutic strategies.

DDIT4L regulates mitochondrial and innate immune activities in early life

Pattern recognition receptor responses are profoundly attenuated before the third trimester of gestation in the relatively low-oxygen human fetal environment. However, the mechanisms regulating these responses are uncharacterized. Herein, genome-wide transcription and functional metabolic experiments in primary neonatal monocytes linked the negative mTOR regulator DDIT4L to metabolic stress, cellular bioenergetics, and innate immune activity. Using genetically engineered monocytic U937 cells, we confirmed that DDIT4L overexpression altered mitochondrial dynamics, suppressing their activity, and blunted LPS-induced cytokine responses. We also showed that monocyte mitochondrial function is more restrictive in earlier gestation, resembling the phenotype of DDIT4L-overexpressing U937 cells. Gene expression analyses in neonatal granulocytes and lung macrophages in preterm infants confirmed upregulation of the DDIT4L gene in the early postnatal period and also suggested a potential protective role against inflammation-associated chronic neonatal lung disease. Taken together, these data show that DDIT4L regulates mitochondrial activity and provide what we believe to be the first direct evidence for its potential role supressing innate immune activity in myeloid cells during development.

Incidence and risk factors of neonatal bacterial infections: a community-based cohort from Madagascar (2018-2021)

BACKGROUND

Few studies on neonatal severe bacterial infection are available in LMICs. Data are needed in these countries to prioritize interventions and decrease neonatal infections which are a primary cause of neonatal mortality. The BIRDY project (Bacterial Infections and Antimicrobial Drug Resistant among Young Children) was initially conducted in Madagascar, Senegal and Cambodia (BIRDY 1, 2012-2018), and continued in Madagascar only (BIRDY 2, 2018-2021). We present here the BIRDY 2 project whose objectives were (1) to estimate the incidence of neonatal severe bacterial infections and compare these findings with those obtained in BIRDY 1, (2) to identify determinants associated with severe bacterial infection and (3) to specify the antibiotic resistance pattern of bacteria in newborns.

METHODS

The BIRDY 2 study was a prospective community-based mother and child cohort, both in urban and semi-rural areas. All pregnant women in the study areas were identified and enrolled. Their newborns were actively and passively followed-up from birth to 3 months. Data on clinical symptoms developed by the children and laboratory results of all clinical samples investigated were collected. A Cox proportional hazards model was performed to identify risk factors associated with possible severe bacterial infection.

FINDINGS

A total of 53 possible severe bacterial infection and 6 confirmed severe bacterial infection episodes were identified among the 511 neonates followed-up, with more than half occurring in the first 3 days. For the first month period, the incidence of confirmed severe bacterial infection was 11.7 per 1,000 live births indicating a 1.3 -fold decrease compared to BIRDY 1 in Madagascar (p = 0.50) and the incidence of possible severe bacterial infection was 76.3, indicating a 2.6-fold decrease compared to BIRDY 1 in Madagascar (p < 0.001). The 6 severe bacterial infection confirmed by blood culture included 5 Enterobacterales and one Enterococcus faecium. The 5 Enterobacterales were extended-spectrum β-lactamases (ESBL) producers and were resistant to quinolones and gentamicin. Enterococcus faecium was sensitive to vancomycin but resistant to amoxicillin and to gentamicin. These pathogns were classified as multidrug-resistant bacteria and were resistant to antibiotics recommended in WHO guidelines for neonatal sepsis. However, they remained susceptible to carbapenem. Fetid amniotic fluid, need for resuscitation at birth and low birth weight were associated with early onset possible severe bacterial infection.

CONCLUSION

Our results suggest that the incidence of severe bacterial infection is still high in the community of Madagascar, even if it seems lower when compared to BIRDY 1 estimates, and that existing neonatal sepsis treatment guidelines may no longer be appropriate in Madagascar. These results motivate to further strengthen actions for the prevention, early diagnosis and case management during the first 3 days of life.

New Insights in Immunometabolism in Neonatal Monocytes and Macrophages in Health and Disease

It is well established that the neonatal immune system is different from the adult immune system. A major task of the neonatal immune system is to bridge the achievement of tolerance towards harmless antigens and commensal bacteria while providing protection against pathogens. This is highly important because neonates are immunologically challenged directly after birth by a rigorous change from a semi-allogeneic sterile environment into a world rich with microbes. A so called disease tolerogenic state is typical for neonates and is anticipated to prevent immunopathological damage potentially at the cost of uncontrolled pathogen proliferation. As a consequence, neonates are more susceptible than adults to life-threatening infections. At the basis of a well-functioning immune response, both for adults and neonates, innate immune cells such as monocytes and monocyte-derived macrophages play an essential role. A well-responsive monocyte will alter its cellular metabolism to subsequently induce certain immune effector function, a process which is called immunometabolism. Immunometabolism has received extensive attention in the last decade; however, it has not been broadly studied in neonates. This review focuses on carbohydrate metabolism in monocytes and macrophages in neonates. We will exhibit pathways involving glycolysis, the tricarboxylic acid (TCA) cycle and oxidative phosphorylation and their role in shaping neonates' immune systems to a favorable tolerogenic state. More insight into these pathways will elucidate potential treatments targets in life-threatening conditions including neonatal sepsis or expose potential targets which can be used to induce tolerance in conditions where tolerance is harmfully impaired such as in autoimmune diseases.

Exploring Immunome and Microbiome Interplay in Reproductive Health: Current Knowledge, Challenges, and Novel Diagnostic Tools

The dynamic interplay between the immunome and microbiome in reproductive health is a complex and rapidly advancing research field, holding tremendously vast possibilities for the development of reproductive medicine. This immunome-microbiome relationship influences the innate and adaptive immune responses, thereby affecting the onset and progression of reproductive disorders. However, the mechanisms governing these interactions remain elusive and require innovative approaches to gather more understanding. This comprehensive review examines the current knowledge on reproductive microbiomes across various parts of female reproductive tract, with special consideration of bidirectional interactions between microbiomes and the immune system. Additionally, it explores innate and adaptive immunity, focusing on immunoglobulin (Ig) A and IgM antibodies, their regulation, self-antigen tolerance mechanisms, and their roles in immune homeostasis. This review also highlights ongoing technological innovations in microbiota research, emphasizing the need for standardized detection and analysis methods. For instance, we evaluate the clinical utility of innovative technologies such as Phage ImmunoPrecipitation Sequencing (PhIP-Seq) and Microbial Flow Cytometry coupled to Next-Generation Sequencing (mFLOW-Seq). Despite ongoing advancements, we emphasize the need for further exploration in this field, as a deeper understanding of immunome-microbiome interactions holds promise for innovative diagnostic and therapeutic strategies for reproductive health, like infertility treatment and management of pregnancy.

The Role of Coagulase-Negative Staphylococci Biofilms on Late-Onset Sepsis: Current Challenges and Emerging Diagnostics and Therapies

Infections are one of the most significant complications of neonates, especially those born preterm, with sepsis as one of the principal causes of mortality. Coagulase-negative staphylococci (CoNS), a group of staphylococcal species that naturally inhabit healthy human skin and mucosa, are the most common cause of late-onset sepsis, especially in preterms. One of the risk factors for the development of CoNS infections is the presence of implanted biomedical devices, which are frequently used for medications and/or nutrient delivery, as they serve as a scaffold for biofilm formation. The major concerns related to CoNS infections have to do with the increasing resistance to multiple antibiotics observed among this bacterial group and biofilm cells’ increased tolerance to antibiotics. As such, the treatment of CoNS biofilm-associated infections with antibiotics is increasingly challenging and considering that antibiotics remain the primary form of treatment, this issue will likely persist in upcoming years. For that reason, the development of innovative and efficient therapeutic measures is of utmost importance. This narrative review assesses the current challenges and emerging diagnostic tools and therapies for the treatment of CoNS biofilm-associated infections, with a special focus on late-onset sepsis.

A20 and the noncanonical NF-κB pathway are key regulators of neutrophil recruitment during fetal ontogeny

Newborns are at high risk of developing neonatal sepsis, particularly if born prematurely. This has been linked to divergent requirements the immune system has to fulfill during intrauterine compared with extrauterine life. By transcriptomic analysis of fetal and adult neutrophils, we shed new light on the molecular mechanisms of neutrophil maturation and functional adaption during fetal ontogeny. We identified an accumulation of differentially regulated genes within the noncanonical NF-κB signaling pathway accompanied by constitutive nuclear localization of RelB and increased surface expression of TNF receptor type II in fetal neutrophils, as well as elevated levels of lymphotoxin α in fetal serum. Furthermore, we found strong upregulation of the negative inflammatory regulator A20 (Tnfaip3) in fetal neutrophils, which was accompanied by pronounced downregulation of the canonical NF-κB pathway. Functionally, overexpressing A20 in Hoxb8 cells led to reduced adhesion of these neutrophil-like cells in a flow chamber system. Conversely, mice with a neutrophil-specific A20 deletion displayed increased inflammation in vivo. Taken together, we have uncovered constitutive activation of the noncanonical NF-κB pathway with concomitant upregulation of A20 in fetal neutrophils. This offers perfect adaption of neutrophil function during intrauterine fetal life but also restricts appropriate immune responses particularly in prematurely born infants.

Immunoglobulin G and subclasses placental transfer in fetuses and preterm newborns: a systematic review

Immunoglobulin G (IgG) and subclasses are the only class of antibodies capable of crossing placenta and providing protection against neonatal infectious diseases, especially in premature infants. This systematic review aimed to review the literature concerning the transplacental transfer of IgG and its subclasses in fetuses and preterm newborns and compare the results with data from term neonates. Eleven studies were included in the final review. Most studies demonstrated a lower transplacental passage of IgG2 than other subclasses in term and preterm newborns and a more efficient passage of total IgG and IgG1 after 37 weeks of gestational age. These results elucidate the physiology of IgG subclass transfer during pregnancy and may explain one of the reasons preterm newborns are especially susceptible to specific pathogens, such as encapsulated bacteria.

Reducing catheter related bloodstream infection risk of infant with a prophylactic antibiotic therapy before removing peripherally inserted central catheter: A retrospective study

PURPOSE

This study examined the efficacy of prescribing antibiotics, specifically a single dose of vancomycin, in reducing the incidence of culture-positive and culture-negative sepsis prior to the removal of peripherally inserted central catheters (PICCs).

MATERIALS AND METHODS

We retrospectively reviewed charts of infants who had PICCs in a tertiary level hospital during the period from 2010 to 2019. The incidence of post-catheter removal clinical sepsis between the groups with or without antibiotics was compared. The antibiotic group was defined by receiving a single dose of vancomycin or any other antibiotic prior to line removal.

RESULTS

We enrolled 585 PICC removal episodes in 546 infants for analysis. Antibiotics were given prior to removal in 257 cases (43.9%) and not given prior to removal in 328 cases (56.1%). There were 13 episodes of post-catheter removal clinical sepsis detected within 72 h (2.2%), 2 of which were culture-positive (0.3%). A 9.3-fold decrease in the odds for clinical sepsis was observed in the antibiotic group (p = 0.01). The incidence of post-catheter removal sepsis was decreased by a single prophylactic dose of vancomycin (p = 0.02), whereas the use of other antibiotics showed no effect (p = 0.35). Logistic regression analysis demonstrated that comorbidities with gastrointestinal diseases (p = 0.01), PICC insertion sites in the scalp and neck (p = 0.04), and no vancomycin administration prior to line removal (p = 0.02) were independent risk factors for subsequent clinical sepsis.

CONCLUSION

A single prophylactic dose of vancomycin prior to PICC line removal might reduce clinical sepsis events in infants.

Development of the immune system in the human embryo

The fetal immune system is highly specialized which is to generate both tolerogenic and protective immune responses to tolerate both self- and maternal-antigens. Fetal T cells with pro-inflammatory potential are born in a tolerogenic environment and are tightly controlled by both cell-intrinsic and -extrinsic mechanisms. Fetal B-1 and B-2 B cells involved in innate and adaptive immune responses, respectively, arise in staggered waves of development from distinct progenitors. Innate immune responses are the key to the protection against infection and adaptive immunity creates memory after an initial response to a specific pathogen. This review aims to discuss the recent advances in understanding the development of immune system in fetus. IMPACT: During gestation, essential developmental changes occur to survive the neonates. At early stage, developmental signals and changes may be influenced due to immune deficiencies.

Induction of Trained Immunity Protects Neonatal Mice Against Microbial Sepsis by Boosting Both the Inflammatory Response and Antimicrobial Activity

Background

Neonates are susceptible to a wide range of microbial infection and at a high risk to develop severe sepsis and septic shock. Emerged evidence has shown that induction of trained immunity triggers a much stronger inflammatory response in adult monocytes/macrophages, thereby conferring protection against microbial infection.

Methods

This study was carried out to examine whether trained immunity is inducible and exerts its protection against microbial sepsis in neonates.

Results

Induction of trained immunity by Bacillus Calmette-Guerin (BCG) plus bacterial lipoprotein (BLP) protected neonatal mice against cecal slurry peritonitis-induced polymicrobial sepsis, and this protection is associated with elevated circulating inflammatory cytokines, increased neutrophil recruitment, and accelerated bacterial clearance. In vitro stimulation of neonatal murine macrophages with BCG+BLP augmented both inflammatory response and antimicrobial activity. Notably, BCG+BLP stimulation resulted in epigenetic remodeling characterized by histone modifications with enhanced H3K4me3, H3K27Ac, and suppressed H3K9me3 at the promoters of the targeted inflammatory and antimicrobial genes. Critically, BCG+BLP stimulation led to a shift in cellular metabolism with increased glycolysis, which is the prerequisite for subsequent BCG+BLP-triggered epigenetic reprogramming and augmented inflammatory response and antimicrobial capacity.

Conclusion

These results illustrate that BCG+BLP induces trained immunity in neonates, thereby protecting against microbial infection by boosting both inflammatory and antimicrobial responses.

Inborn Errors of Immunity in the Premature Infant: Challenges in Recognition and Diagnosis

Due to heightened awareness and advanced genetic tools, inborn errors of immunity (IEI) are increasingly recognized in children. However, diagnosing of IEI in premature infants is challenging and, subsequently, reports of IEI in premature infants remain rare. This review focuses on how common disorders of prematurity, such as sepsis, necrotizing enterocolitis, and bronchopulmonary dysplasia, can clinically overlap with presenting signs of IEI. We present four recent cases from a single neonatal intensive care unit that highlight diagnostic dilemmas facing neonatologists and clinical immunologists when considering IEI in preterm infants. Finally, we present a conceptual framework for when to consider IEI in premature infants and a guide to initial workup of premature infants suspected of having IEI.

Group B streptococci infection model shows decreased regulatory capacity of cord blood cells

BACKGROUND

Sepsis is one of the leading causes of morbidity and mortality in the neonatal period. Compared to adults, neonates are more susceptible to infections, especially to systemic infections with Group B Streptococcus (GBS). Furthermore, neonates show defects in terminating inflammation. The immunological causes for the increased susceptibility to infection and the prolonged inflammatory response are still incompletely understood.

METHODS

In the present study, we aimed to investigate the reaction of cord blood mononuclear cells (MNC) to stimulation with GBS in comparison to that of MNC from adult blood with focus on the proliferative response in an in vitro infection model with heat-inactivated GBS.

RESULTS

We demonstrate that after stimulation with GBS the proliferation of T cells from adult blood strongly decreased, while the proliferation of cord blood T cells remained unchanged. This effect could be traced back to a transformation of adult monocytes, but not cord blood monocytes, to a suppressive phenotype with increased expression of the co-inhibitory molecule programmed death ligand 1 (PD-L1).

CONCLUSIONS

These results point towards an increased inflammatory capacity of neonatal MNC after stimulation with GBS. Targeting the prolonged inflammatory response of neonatal immune cells may be a strategy to prevent complications of neonatal infections.

IMPACT

Neonatal sepsis often leads to post-inflammatory complications. Causes for sustained inflammation in neonates are incompletely understood. We show that cord blood T cells exhibited increased proliferative capacity after stimulation with group B streptococci (GBS) in comparison to adult T cells. Adult monocytes but not cord blood monocytes acquired suppressive activity and expressed increased levels of PD-L1 after GBS stimulation. Increased proliferative capacity of neonatal T cells and decreased suppressive activity of neonatal monocytes during GBS infection may contribute to prolonged inflammation and development of post-inflammatory diseases in newborns.

Current-proven neonatal sepsis in Indonesian tertiary neonatal intensive care unit: a hematological and microbiological profile

Background and Objectives:

Neonatal sepsis is the third leading cause of neonatal death in the world. The patterns of pathogens causing neonatal sepsis varies in many countries. This study was aimed to identify hematological and microbiological profile of culture-proven neonatal sepsis in Indonesian tertiary neonatal intensive care unit (NICU).

Materials and Methods:

Hospital based cross-sectional study was conducted in all inborn neonates that were suspected sepsis neonatal over a period of six months from April to September 2019. Complete blood count, c-reactive protein (CRP) and blood culture were examined before antibiotic administration. Statistical analysis were calculated based on Chi-Square’s Test and Mann-Whitney U test and p <0.05 considered significant.

Results:

One hundred four inborn neonates admitted to NICU and diagnosed with suspected neonatal sepsis were recruited. Culture-proven neonatal sepsis were confirmed in 52 (50%) neonates, 13 (25%) in early-onset neonatal sepsis (EONS) and 39 (75%) in late-onset neonatal sepsis (LONS). The most common abnormal hematological profile were anemia and thrombocytopenia, with amount of 61.5% and 75%, respectively. High CRP only detected in 36.4% and only 18.5% experienced leukopenia. Gram negative bacteria responsible in 75% from total isolated pathogens. Klebsiella pneumoniae accounted for 48.1% followed by coagulase negative staphylococci (CONS) for 17.3% and Enterobacter cloacae for 11.5%.

Conclusion:

Anemia and thrombocytopenia were the top two hematological profile of culture-proven neonatal sepsis. Most causes of culture-proven neonatal sepsis were Gram negative bacteria and the dominant pathogen was K. pneumoniae.

The immunological link between neonatal lung and eye disease

Bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) are two neonatal diseases of major clinical importance, arising in large part as a consequence of supplemental oxygen therapy used to promote the survival of preterm infants. The presence of coincident inflammation in the lungs and eyes of neonates receiving oxygen therapy indicates that a dysregulated immune response serves as a potential common pathogenic factor for both diseases. This review examines the current state of knowledge of immunological dysregulation in BPD and ROP, identifying similarities in the cellular subsets and inflammatory cytokines that are found in the alveoli and retina during the active phase of these diseases, indicating possible mechanistic overlap. In addition, we highlight gaps in the understanding of whether these responses emerge independently in the lung and retina as a consequence of oxygen exposure or arise because of inflammatory spill-over from the lung. As BPD and ROP are anatomically distinct, they are often considered discreet disease entities and are therefore treated separately. We propose that an improved understanding of the relationship between BPD and ROP is key to the identification of novel therapeutic targets to treat or prevent both conditions simultaneously.

Risk factors for the development of neonatal sepsis in a neonatal intensive care unit of a tertiary care hospital of Nepal

BACKGROUND

Sepsis is an overwhelming and life-threatening response to bacteria in bloodstream and a major cause of neonatal morbidity and mortality. Understanding the etiology and potential risk factors for neonatal sepsis is urgently required, particularly in low-income countries where burden of infection is high and its epidemiology is poorly understood.

METHODS

A prospective observational cohort study was conducted between April 2016 and October 2017 in a level three NICU at a tertiary care hospital in Nepal to determine the bacterial etiology and potential risk factors for neonatal sepsis.

RESULTS

Among 142 NICU admitted neonates, 15% (21/142) and 32% (46/142) developed blood culture-positive and -negative neonatal sepsis respectively. Klebsiella pneumoniae (34%, 15/44) and Enterobacter spp. (25%, 11/44) were the most common isolates. The antimicrobial resistance of isolates to ampicillin (100%, 43/43), cefotaxime (74%, 31/42) and ampicillin-sulbactam (55%, 21/38) were the highest. BlaTEM (53%, 18/34) and blaKPC (46%, 13/28) were the commonest ESBL and carbapenemase genes respectively. In univariate logistic regression, the odds of sepsis increased with each additional day of use of invasive procedures such as mechanical ventilation (OR 1.086, 95% CI 1.008-1.170), umbilical artery catheter (OR 1.375, 95% CI 1.049-1.803), intravenous cannula (OR 1.140, 95% CI 1.062-1.225); blood transfusion events (OR 3.084, 95% CI 1.407-6.760); NICU stay (OR 1.109, 95% CI 1.040-1.182) and failure to breast feed (OR 1.130, 95% CI 1.060-1.205). Sepsis odds also increased with leukopenia (OR 1.790, 95% CI 1.04-3.082), increase in C-reactive protein (OR 1.028, 95% CI 1.016-1.040) and decrease in platelets count (OR 0.992, 95% CI 0.989-0.994). In multivariate analysis, increase in IV cannula insertion days (OR 1.147, 95% CI 1.039-1.267) and CRP level (OR 1.028, 95% CI 1.008-1.049) increased the odds of sepsis.

CONCLUSIONS

Our study indicated various nosocomial risk factors and underscored the need to improve local infection control measures so as to reduce the existing burden of sepsis. We have highlighted certain sepsis associated laboratory parameters along with identification of antimicrobial resistance genes, which can guide for early and better therapeutic management of sepsis. These findings could be extrapolated to other low-income settings within the region.

Neonatal lymphocyte subpopulations analysis and maternal preterm premature rupture of membranes: a pilot study

OBJECTIVES

Preterm premature rupture of membranes (pPROM) causes preterm delivery, and increases maternal T-cell response against the fetus. Fetal inflammatory response prompts maturation of the newborn's immunocompetent cells, and could be associated with unfavorable neonatal outcome. The aims were (1) to examine the effects of pPROM on the newborn's and mother's immune system and (2) to assess the predictive value of immune system changes in neonatal morbidity.

METHODS

Mother-newborn pairs (18 mothers and 23 newborns) who experienced pPROM and controls (11 mothers and 14 newborns), were enrolled. Maternal and neonatal whole blood samples underwent flow cytometry to measure lymphocyte subpopulations.

RESULTS

pPROM-newborns had fewer naïve CD4 T-cells, and more memory CD4 T-cells than control newborns. The effect was the same for increasing pPROM latency times before delivery. Gestational age and birth weight influenced maturation of the newborns' lymphocyte subpopulations and white blood cells, notably cytotoxic T-cells, regulatory T-cells, T-helper cells (absolute count), and CD4/CD8 ratio. Among morbidities, fewer naïve CD8 T-cells were found in bronchopulmonary dysplasia (BPD) (p=0.0009), and more T-helper cells in early onset sepsis (p=0.04).

CONCLUSIONS

pPROM prompts maturation of the newborn's T-cell immune system secondary to antigenic stimulation, which correlates with pPROM latency. Maternal immunity to inflammatory conditions is associated with a decrease in non-major histocompatibility complex (MHC)-restricted cytotoxic cells.

Antibiotic regimens for early-onset neonatal sepsis

BACKGROUND

Neonatal sepsis is a major cause of morbidity and mortality. It is the third leading cause of neonatal mortality globally constituting 13% of overall neonatal mortality. Despite the high burden of neonatal sepsis, high-quality evidence in diagnosis and treatment is scarce. Possibly due to the diagnostic challenges of sepsis and the relative immunosuppression of the newborn, many neonates receive antibiotics for suspected sepsis. Antibiotics have become the most used therapeutics in neonatal intensive care units. The last Cochrane Review was updated in 2004. Given the clinical importance, an updated systematic review assessing the effects of different antibiotic regimens for early-onset neonatal sepsis is needed.

OBJECTIVES

To assess the beneficial and harmful effects of different antibiotic regimens for early-onset neonatal sepsis.

SEARCH METHODS

We searched the following electronic databases: CENTRAL (2020, Issue 8); Ovid MEDLINE; Embase Ovid; CINAHL; LILACS; Science Citation Index EXPANDED and Conference Proceedings Citation Index - Science on 12 March 2021. We searched clinical trials databases and the reference lists of retrieved articles for randomised controlled trials (RCTs) and quasi-RCTs.

SELECTION CRITERIA

We included RCTs comparing different antibiotic regimens for early-onset neonatal sepsis. We included participants from birth to 72 hours of life at randomisation.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed studies for inclusion, extracted data, and assessed risk of bias. We used the GRADE approach to assess the certainty of evidence. Our primary outcome was all-cause mortality, and our secondary outcomes were: serious adverse events, respiratory support, circulatory support, nephrotoxicity, neurological developmental impairment, necrotising enterocolitis, and ototoxicity. Our primary time point of interest was at maximum follow-up.

MAIN RESULTS

We included five RCTs (865 participants). All trials were at high risk of bias. The certainty of the evidence according to GRADE was very low. The included trials assessed five different comparisons of antibiotics. We did not conduct any meta-analyses due to lack of relevant data. Of the five included trials one trial compared ampicillin plus gentamicin with benzylpenicillin plus gentamicin; one trial compared piperacillin plus tazobactam with amikacin; one trial compared ticarcillin plus clavulanic acid with piperacillin plus gentamicin; one trial compared piperacillin with ampicillin plus amikacin; and one trial compared ceftazidime with benzylpenicillin plus gentamicin. None of the five comparisons found any evidence of a difference when assessing all-cause mortality, serious adverse events, circulatory support, nephrotoxicity, neurological developmental impairment, or necrotising enterocolitis; however, none of the trials were near an information size that could contribute significantly to the evidence of the comparative benefits and risks of any particular antibiotic regimen. None of the trials assessed respiratory support or ototoxicity. The benefits and harms of different antibiotic regimens remain unclear due to the lack of well-powered trials and the high risk of systematic errors.

AUTHORS' CONCLUSIONS

Current evidence is insufficient to support any antibiotic regimen being superior to another. Large RCTs assessing different antibiotic regimens in early-onset neonatal sepsis with low risk of bias are warranted.

Antibiotic regimens for late-onset neonatal sepsis

BACKGROUND

Neonatal sepsis is a major cause of morbidity and mortality. It is the third leading cause of neonatal mortality globally constituting 13% of overall neonatal mortality. Despite the high burden of neonatal sepsis, high-quality evidence in diagnosis and treatment is scarce. Due to the diagnostic challenges of sepsis and the relative immunosuppression of the newborn, many neonates receive antibiotics for suspected sepsis. Antibiotics have become the most used therapeutics in neonatal intensive care units, and observational studies in high-income countries suggest that 83% to 94% of newborns treated with antibiotics for suspected sepsis have negative blood cultures. The last Cochrane Review was updated in 2005. There is a need for an updated systematic review assessing the effects of different antibiotic regimens for late-onset neonatal sepsis.

OBJECTIVES

To assess the beneficial and harmful effects of different antibiotic regimens for late-onset neonatal sepsis.

SEARCH METHODS

We searched the following electronic databases: CENTRAL (2021, Issue 3); Ovid MEDLINE; Embase Ovid; CINAHL; LILACS; Science Citation Index EXPANDED and Conference Proceedings Citation Index - Science on 12 March 2021. We also searched clinical trials databases and the reference lists of retrieved articles for randomised controlled trials (RCTs) and quasi-RCTs.

SELECTION CRITERIA

We included RCTs comparing different antibiotic regimens for late-onset neonatal sepsis. We included participants older than 72 hours of life at randomisation, suspected or diagnosed with neonatal sepsis, meningitis, osteomyelitis, endocarditis, or necrotising enterocolitis. We excluded trials that assessed treatment of fungal infections.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed studies for inclusion, extracted data, and assessed risk of bias. We used the GRADE approach to assess the certainty of evidence. Our primary outcome was all-cause mortality, and our secondary outcomes were: serious adverse events, respiratory support, circulatory support, nephrotoxicity, neurological developmental impairment, necrotising enterocolitis, and ototoxicity. Our primary time point of interest was at maximum follow-up.

MAIN RESULTS

We included five RCTs (580 participants). All trials were at high risk of bias, and had very low-certainty evidence. The five included trials assessed five different comparisons of antibiotics. We did not conduct a meta-analysis due to lack of relevant data. Of the five included trials one trial compared cefazolin plus amikacin with vancomycin plus amikacin; one trial compared ticarcillin plus clavulanic acid with flucloxacillin plus gentamicin; one trial compared cloxacillin plus amikacin with cefotaxime plus gentamicin; one trial compared meropenem with standard care (ampicillin plus gentamicin or cefotaxime plus gentamicin); and one trial compared vancomycin plus gentamicin with vancomycin plus aztreonam. None of the five comparisons found any evidence of a difference when assessing all-cause mortality, serious adverse events, circulatory support, nephrotoxicity, neurological developmental impairment, or necrotising enterocolitis; however, none of the trials were near an information size that could contribute significantly to the evidence of the comparative benefits and risks of any particular antibiotic regimen. None of the trials assessed respiratory support or ototoxicity. The benefits and harms of different antibiotic regimens remain unclear due to the lack of well-powered trials and the high risk of systematic errors.

AUTHORS' CONCLUSIONS

Current evidence is insufficient to support any antibiotic regimen being superior to another. RCTs assessing different antibiotic regimens in late-onset neonatal sepsis with low risks of bias are warranted.

Neonatal T Helper 17 Responses Are Skewed Towards an Immunoregulatory Interleukin-22 Phenotype

Newborns are frequently affected by mucocutaneous candidiasis. Th17 cells essentially limit mucosal invasion by commensal Candida spp. Here, we sought to understand the molecular basis for the developmental lack of Th17 cell responses in circulating blood neonatal T cells. Naive cord blood CD4 T cells stimulated in Th17-differentiating conditions inherently produced high levels of the interleukin-22 immunoregulatory cytokine, particularly in the presence of neonatal antigen-presenting cells. A genome-wide transcriptome analysis comparing neonatal and adult naïve CD4 T cells ex vivo revealed major developmental differences in gene networks regulating Small Drosophila Mothers Against Decapentaplegic (SMAD) and Signal Transducer and Activator of Transcription 3 (STAT3) signaling. These changes were functionally validated by experiments showing that the requirement for TGF-β in human Th17 cell differentiation is age-dependent. Moreover, STAT3 activity was profoundly diminished while overexpression of the STAT3 gene restored Th17 cell differentiation capacity in neonatal T cells. These data reveal that Th17 cell responses are developmentally regulated at the gene expression level in human neonates. These developmental changes may protect newborns against pathological Th17 cell responses, at the same time increasing their susceptibility to mucocutaneous candidiasis.

Detailed nursing intervention on neonatal septicemia can improve the clinical symptoms of children and reduce the inflammatory reaction

OBJECTIVE

To explore the application effect of detailed nursing intervention in neonatal septicemia.

METHODS

Altogether 60 neonates of neonatal septicemia admitted to our hospital from November 2019 to October 2020 were selected as the research participants, and all the children have received routine treatment, among which 30 neonates received routine nursing intervention as the regular group, and the remaining 30 received detailed nursing intervention as the detail group. The clinical effects, improvement of clinical symptoms, length of stay, and guardian satisfaction were compared, and the levels of serum inflammatory factors (TNF-α, IL-6 and IL-17) and immune function indicators (CD4+, CD8+) before and after nursing intervention were detected.

RESULTS

The total effective rate in the detail group was higher than that in the regular group (P < 0.05). Compared with the regular group, the temperature stabilization time, blood culture turning negative time, improvement time of milk rejection and hospital stay in the detail group were significantly shortened (P < 0.05). The guardian satisfaction score in the detail group was higher than that in the regular group (P < 0.05). After nursing, the levels of TNF-α, IL-6 and IL-17 decreased in both groups, and the levels of these three in the detail group were lower than those in the regular group (P < 0.05). After nursing, CD4+/CD8+ of children in both groups increased, and CD4+/CD8+ in the detail group and regular group were higher than those in the regular group (P < 0.05).

CONCLUSION

The adoption of detailed nursing modes in the treatment of neonatal septicemia can further improve the treatment effect, shorten the hospital stay and the improvement time of clinical symptoms, reduce the incidence of complications, improve the nursing satisfaction of guardians, reduce the inflammation of the body and improve the immune function of the body.

Stratified Management for Bacterial Infections in Late Preterm and Term Neonates: Current Strategies and Future Opportunities Toward Precision Medicine

Bacterial infections remain a major cause of morbidity and mortality in the neonatal period. Therefore, many neonates, including late preterm and term neonates, are exposed to antibiotics in the first weeks of life. Data on the importance of inter-individual differences and disease signatures are accumulating. Differences that may potentially influence treatment requirement and success rate. However, currently, many neonates are treated following a "one size fits all" approach, based on general protocols and standard antibiotic treatment regimens. Precision medicine has emerged in the last years and is perceived as a new, holistic, way of stratifying patients based on large-scale data including patient characteristics and disease specific features. Specific to sepsis, differences in disease susceptibility, disease severity, immune response and pharmacokinetics and -dynamics can be used for the development of treatment algorithms helping clinicians decide when and how to treat a specific patient or a specific subpopulation. In this review, we highlight the current and future developments that could allow transition to a more precise manner of antibiotic treatment in late preterm and term neonates, and propose a research agenda toward precision medicine for neonatal bacterial infections.

Targeting the eCIRP/TREM-1 interaction with a small molecule inhibitor improves cardiac dysfunction in neonatal sepsis

Background

Neonatal sepsis and the associated myocardial dysfunction remain a leading cause of infant mortality. Extracellular cold-inducible RNA-binding protein (eCIRP) acts as a ligand of triggering receptor expressed on myeloid cells-1 (TREM-1). M3 is a small CIRP-derived peptide that inhibits the eCIRP/TREM-1 interaction. We hypothesize that the eCIRP/TREM-1 interaction in cardiomyocytes contributes to sepsis-induced cardiac dysfunction in neonatal sepsis, while M3 is cardioprotective.

Methods

Serum was collected from neonates in the Neonatal Intensive Care Unit (NICU). 5–7-day old C57BL/6 mouse pups were used in this study. Primary murine neonatal cardiomyocytes were stimulated with recombinant murine (rm) CIRP with M3. TREM-1 mRNA and supernatant cytokine levels were assayed. Mitochondrial oxidative stress, ROS, and membrane potential were assayed. Neonatal mice were injected with rmCIRP and speckle-tracking echocardiography was conducted to measure cardiac strain. Sepsis was induced by i.p. cecal slurry. Mouse pups were treated with M3 or vehicle. After 16 h, echocardiography was performed followed by euthanasia for tissue analysis. A 7-day survival study was conducted.

Results

Serum eCIRP levels were elevated in septic human neonates. rmCIRP stimulation of cardiomyocytes increased TREM-1 gene expression. Stimulation of cardiomyocytes with rmCIRP upregulated TNF-α and IL-6 in the supernatants, while this upregulation was inhibited by M3. Stimulation of cardiomyocytes with rmCIRP resulted in a reduction in mitochondrial membrane potential (MMP) while M3 treatment returned MMP to near baseline. rmCIRP caused mitochondrial calcium overload; this was inhibited by M3. rmCIRP injection impaired longitudinal and radial cardiac strain. Sepsis resulted in cardiac dysfunction with a reduction in cardiac output and left ventricular end diastolic diameter. Both were improved by M3 treatment. Treatment with M3 attenuated serum, cardiac, and pulmonary levels of pro-inflammatory cytokines compared to vehicle-treated septic neonates. M3 dramatically increased sepsis survival.

Conclusions

Inhibition of eCIRP/TREM-1 interaction with M3 is cardioprotective, decreases inflammation, and improves survival in neonatal sepsis.

Trial registration Retrospectively registered.

Whole blood genome-wide transcriptome profiling and metagenomics next-generation sequencing in young infants with suspected sepsis in a low-and middle-income country: A study protocol

Conducting collaborative and comprehensive epidemiological research on neonatal sepsis in low- and middle-income countries (LMICs) is challenging due to a lack of diagnostic tests. This prospective study protocol aims to obtain epidemiological data on bacterial sepsis in newborns and young infants at Kamuzu Central Hospital in Lilongwe, Malawi. The main goal is to determine if the use of whole blood transcriptome host immune response signatures can help in the identification of infants who have sepsis of bacterial causes. The protocol includes a detailed clinical assessment with vital sign measurements, strict aseptic blood culture protocol with state-of-the-art microbial analyses and RNA-sequencing and metagenomics evaluations of host responses and pathogens, respectively. We also discuss the directions of a brief analysis plan for RNA sequencing data. This study will provide robust epidemiological data for sepsis in neonates and young infants in a setting where sepsis confers an inordinate burden of disease.

The human fetal thymus generates invariant effector γδ T cells

Tieppo et al. show that the human fetal thymus generates invariant γδ T cells with programmed effector functions. This is due to an intrinsic property of fetal HSPCs caused by high expression of the RNA-binding protein Lin28b.

In the mouse thymus, invariant γδ T cells are generated at well-defined times during development and acquire effector functions before exiting the thymus. However, whether such thymic programming and age-dependent generation of invariant γδ T cells occur in humans is not known. Here we found that, unlike postnatal γδ thymocytes, human fetal γδ thymocytes were functionally programmed (e.g., IFNγ, granzymes) and expressed low levels of terminal deoxynucleotidyl transferase (TdT). This low level of TdT resulted in a low number of N nucleotide insertions in the complementarity-determining region-3 (CDR3) of their TCR repertoire, allowing the usage of short homology repeats within the germline-encoded VDJ segments to generate invariant/public cytomegalovirus-reactive CDR3 sequences (TRGV8-TRJP1-CATWDTTGWFKIF, TRDV2-TRDD3-CACDTGGY, and TRDV1-TRDD3-CALGELGD). Furthermore, both the generation of invariant TCRs and the intrathymic acquisition of effector functions were due to an intrinsic property of fetal hematopoietic stem and precursor cells (HSPCs) caused by high expression of the RNA-binding protein Lin28b. In conclusion, our data indicate that the human fetal thymus generates, in an HSPC/Lin28b-dependent manner, invariant γδ T cells with programmed effector functions.

Whole blood genome-wide transcriptome profiling and metagenomics next-generation sequencing in young infants with suspected sepsis in low-and middle-income countries: A study protocol

Conducting collaborative and comprehensive epidemiological research on neonatal sepsis in low- and middle-income countries (LMICs) is challenging due to a lack of diagnostic tests. This prospective study protocol aims to obtain epidemiological data on bacterial sepsis in newborns and young infants at Kamuzu Central Hospital in Lilongwe, Malawi. The main goal is to determine if the use of whole blood transcriptome host immune response signatures can help in the identification of infants who have sepsis of bacterial causes. The protocol includes a detailed clinical assessment with vital sign measurements, strict aseptic blood culture protocol with state-of-the-art microbial analyses and RNA-sequencing and metagenomics evaluations of host responses and pathogens, respectively. We also discuss the directions of a brief analysis plan for RNA sequencing data. This study will provide robust epidemiological data for sepsis in neonates and young infants in a setting where sepsis confers an inordinate burden of disease.

Development and validation of a nomogram for predicting late-onset sepsis in preterm infants on the basis of thyroid function and other risk factors: Mixed retrospective and prospective cohort study

Preterm birth and infection are common causes of neonatal death. In this study, we aimed to develop a nomogram for assessing the individual prior probability of late-onset sepsis on the basis of risk factors in preterm infants. This study is a mixed retrospective and prospective cohort study conducted in three centers. Data from January 2014 to December 2017 was used for the development cohort, and data from January 2018 to December 2018 was used for the validation cohort. In the development cohort, we identified the predicting variables of late-onset sepsis in preterm infants, from which a nomogram was obtained. Then we built nomograms, for with and without thyroid function, to predict late-onset sepsis. The nomogram was validated in the validation cohort concerning discrimination and calibration. A total of 1256 and 452 preterm infants were included in the development and validation cohort, respectively. We found thyroid hypofunction in preterm infants could increase the incidence of late-onset infection. The prediction model incorporated thyroid function, birth weight, use of endotracheal intubation, and duration of umbilical venous catheters was validated and developed as a nomogram for predicting late-onset sepsis in preterm infants. Nomogram in this study may contribute to clinical assessment and treatment decisions.

Whole blood transcriptional responses of very preterm infants during late-onset sepsis

BACKGROUND

Host immune responses during late-onset sepsis (LOS) in very preterm infants are poorly characterised due to a complex and dynamic pathophysiology and challenges in working with small available blood volumes. We present here an unbiased transcriptomic analysis of whole peripheral blood from very preterm infants at the time of LOS.

METHODS

RNA-Seq was performed on peripheral blood samples (6-29 days postnatal age) taken at the time of suspected LOS from very preterm infants <30 weeks gestational age. Infants were classified based on blood culture positivity and elevated C-reactive protein concentrations as having confirmed LOS (n = 5), possible LOS (n = 4) or no LOS (n = 9). Bioinformatics and statistical analyses performed included pathway over-representation and protein-protein interaction network analyses. Plasma cytokine immunoassays were performed to validate differentially expressed cytokine pathways.

RESULTS

The blood leukocyte transcriptional responses of infants with confirmed LOS differed significantly from infants without LOS (1,317 differentially expressed genes). However, infants with possible LOS could not be distinguished from infants with no LOS or confirmed LOS. Transcriptional alterations associated with LOS included genes involved in pathogen recognition (mainly TLR pathways), cytokine signalling (both pro-inflammatory and inhibitory responses), immune and haematological regulation (including cell death pathways), and metabolism (altered cholesterol biosynthesis). At the transcriptional-level cytokine responses during LOS were characterised by over-representation of IFN-α/β, IFN-γ, IL-1 and IL-6 signalling pathways and up-regulation of genes for inflammatory responses. Infants with confirmed LOS had significantly higher levels of IL-1α and IL-6 in their plasma.

CONCLUSIONS

Blood responses in very preterm infants with LOS are characterised by altered host immune responses that appear to reflect unbalanced immuno-metabolic homeostasis.

The Role of Iron in the Susceptibility of Neonatal Mice to Escherichia coli K1 Sepsis

Sepsis from Escherichia coli expressing the K1 antigen is a leading cause of death in neonates. In a murine model, E. coli K1 grew rapidly in the peritoneal cavity of neonatal mice, causing fatal disease. In contrast, adult mice cleared the infection. Neonatal mice mounted a rapid and equivalent antimicrobial immune response compared to adult mice. Interestingly, peritoneal fluid from neonatal mice contained significantly more total iron than that of adult mice, which was sufficient to support enhanced E. coli growth. Transient iron overload in adult mice infected with E. coli resulted in 100% mortality. Maternal diet-induced mild iron deficiency decreased offspring peritoneal iron, decreased bacterial growth, and conferred protection against sepsis. Taken together, neonatal susceptibility to E. coli K1 sepsis is enhanced by a localized excess of peritoneal iron that allows for unchecked bacterial growth. Targeting this excess iron may provide a new therapeutic target in human patients.

S100-Alarmins Are Essential Pilots of Postnatal Innate Immune Adaptation

The restricted capacity of newborn infants to mount inflammatory responses toward microbial challenges has traditionally been linked to the high risk of septic diseases during the neonatal period. In recent years, substantial evidence has been provided that this characteristic of the neonatal immune system is actually a meaningful physiologic state that is based on specific transiently active cellular and molecular mechanisms and required for a favorable course of postnatal immune adaptation. The identification of physiologically high amounts of S100-alarmins in neonates has been one of the crucial pieces in the puzzle that contributed to the change of concept. In this context, innate immune immaturity could be redefined and assigned to the epigenetic silence of adult-like cell-autonomous regulation at the beginning of life. S100-alarmins represent an alternative age-specific mechanism of immune regulation that protects neonates from hyperinflammatory immune responses. Here, we summarize how infants are provided with S100-alarmins and why these allow an uneventful clash between the innate immune system and the extrauterine world. The mode of action of S100-alarmins is highlighted including their tuning functions at multiple levels for establishing a state of homeostasis with the environment in the newborn individual.

Literature review on the distribution characteristics and antimicrobial resistance of bacterial pathogens in neonatal sepsis

Purpose: Neonatal sepsis (NS) has no specific clinical manifestations and blood culture analysis requires a long period of time. Knowledge of prevalent bacterial isolates and their antibiotic susceptibility is crucial when choosing an empirical therapy to decrease morbidity and mortality. This literature review summarizes the distribution characteristics and antimicrobial resistance of bacterial pathogens associated with bloodstream infections in Chinese neonates, and thus serves as a reference for pediatricians.Methods: The full-text journal database, CNKI, was searched using the key words "neonatal", "sepsis", and "bacterial pathogen" to retrieve relevant literature published from 2016 up to April 2018. The following data were extracted from the selected papers: title, pathogen collection time, care unit name, province (city), distribution of bacterial pathogens among bloodstream infections, and antimicrobial resistance of major pathogens.Results: A total of 86 articles were searched, of which 30 complied with the study requirements and thus were included in the review; all were retrospective studies. The articles covered a total of 4098 bacterial strains from 24 cities (2494 Gram-positive bacteria, 1429 Gram-negative bacteria, 176 fungi). Among the Gram-positive bacteria, the four pathogens with the highest detection rates were coagulase-negative staphylococci (CoNS) (40.23%), Streptococci (6.81%), Enterococci (6.10%), and Staphylococcus aureus (S. aureus) (5.15%); among the Gram-negative bacteria, Klebsiella (14.52%), Escherichia coli (12.12%), Enterobacter cloacae (1.90%), and Pseudomonas (1.41%) had the highest detection rates. The detection rate of Candida and other fungi was 4.29%. Among the pathogens with high clinical detection rates, S. epidermidis and S. aureus are highly resistant to both erythromycin and penicillin. Antibacterial drugs with high efficacy for both S. epidermidis and S. aureus include vancomycin, ciprofloxacin, gentamicin, linezolid, rifampicin, and tetracycline. Klebsiella pneumoniae and Escherichia coli are highly resistant to ampicillin, but there are drugs with high efficacy for both, including imipenem, piperacillin/tazobactam, aminoglycosides (gentamicin, amikacin), and quinolones (levofloxacin, ciprofloxacin). In contrast to the drug resistance data reported by the China Antimicrobial Resistance Surveillance System (CARSS) in 2017, the detection rate of methicillin-resistant S. aureus (MRSA) and methicillin-resistant coagulase-negative staphylococci (MRCoNS) in the blood cultures of neonates with sepsis exceeded the national average drug resistance level (p < .01). The resistance rate of K. pneumoniae to third-generation cephalosporins was higher than the national average drug resistance level (p < .01), but this organism was most sensitive to carbapenems (carbapenem resistance refers to resistance to any of imipenem, meropenem, or ertapenem). The resistance of Escherichia coli to quinolones was better than the national average level (p < .01).Conclusions: Medical care-related infections in neonatal intensive care units (NICUs) were more often caused by CoNS than by S. aureus and Gram-negative bacteria. Vancomycin remains the preferred drug for treating confirmed infections, because most isolated CoNS are resistant to β-lactam drugs including penicillin. For Gram-negative enteric bacteria, aminoglycoside and carbapenem were sufficient for treatment. Compared to the CARSS data on bacterial resistance, the data in this review on the resistance of pathogens causing NS were not favorable. The next goal in antibiotic management in NICUs must be to develop strategies to reduce the use of antibiotics.

Neonatal sepsis in low-income countries: epidemiology, diagnosis and prevention

Introduction: Sepsis accounts for up to one-third of neonatal deaths in the world each year. The World Health Organization acknowledges neonatal sepsis as a major global health concern, and that the highest burden occurs in low- and middle-income countries (LMICs). Despite major research and clinical progress in this area, we still lack accurate diagnostic tools for neonatal sepsis, complicating the management of this condition.Areas covered: The purpose here is to review the latest data on the incidence, diagnosis, prevention, and management of neonatal sepsis in LMIC. We discuss the limitations of current diagnostic tests - including their lack of availability - and how this may influence global estimates of cases. We review the benefits of antenatal, intrapartum, and post-natal preventive measures. We briefly discuss the management, highlighting the emergence of antimicrobial resistance. Finally, we expose some high priority areas.Expert opinion: Neonatal sepsis is a challenging condition requiring a multifaceted approach to address the major diagnostic issues, but also the underlying socio-economic causes that nourish epidemic cases in LMIC. Focusing on antibiotics as a main pillar of intervention is likely to engender antimicrobial resistance, eventually hindering the appreciable gains LMICs have achieved in neonatal health outcomes.

Effects of diet on skin sensitization by nickel, poison ivy, and sesquiterpene lactones

Skin contact or exposure to sensitizers often occurs as a consequence of occupational exposures (e.g. poison ivy in forestry), wearing jewelry (e.g. nickel), or use of cosmetics (e.g. fragrances). However, many of the known skin sensitizers or their chemical variants are also consumed orally through foods or other sources. Since oral exposure to antigenic substances can lead to tolerance, consumption of sensitizers may impact the development and potency of skin sensitization, especially if the sensitizer is consumed early in life, prior to the first skin contact. To address this issue, we have reviewed human clinical and epidemiological literature relevant to this subject and evaluated whether early oral exposures to relevant sensitizers, or their chemical variants, are associated with reduced prevalence of skin sensitization to three main allergic sensitizers - nickel, urushiols of poison ivy, and sesquiterpene lactones of chrysanthemum and other plants.

Antibiotic regimens for neonatal sepsis - a protocol for a systematic review with meta-analysis

BACKGROUND

Sepsis is a major cause of morbidity and mortality among neonates and infants. Antibiotics are a central part of the first line treatment for sepsis in neonatal intensive care units worldwide. However, the evidence on the clinical effects of the commonly used antibiotic regimens for sepsis in neonates remains scarce. This systematic review aims to assess the efficacy and harms of antibiotic regimens for neonatal sepsis.

METHODS

Electronic searches will be conducted in MEDLINE, Embase, The Cochrane Library, CINAHL, ZETOC and clinical trial registries (clinicaltrials.gov and ISRCTN). We will include randomised controlled trials of different antibiotic regimens for sepsis of neonates and infants. Eligible interventions will be any antibiotic regimen. Two reviewers will independently screen, select, and extract data. The methodological quality of individual studies will be appraised following Cochrane methodology. Primary outcomes will be 'all-cause mortality' and 'serious adverse events'. Secondary outcomes will be 'need for respiratory support', 'need for circulatory support', 'neurodevelopmental impairment', ototoxicity, nephrotoxicity and necrotizing enterocolitis. We plan to perform a meta-analysis with trial sequential analysis.

DISCUSSION

This is the study protocol for a systematic review on the effects of different antibiotic regimens for neonatal sepsis. The results of this systematic review intent to adequately inform stakeholders or health care professionals in the field of neonatal sepsis, and to aid appropriate development of treatment guidelines.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO reference number: CRD42019134300.

Sepsis roadmap: What we know, what we learned, and where we are going

Sepsis is a life-threatening condition originating as a result of systemic blood infection causing, one or more organ damage due to the dysregulation of the immune response. In 2017, the world health organization (WHO) declared sepsis as a disease of global health priority, needing special attention due to its high prevalence and mortality around the world. Most of the therapeutics targeting sepsis have failed in the clinics. The present review highlights the history of the sepsis, its immunopathogenesis, and lessons learned after the failure of previously used immune-based therapies. The subsequent section, where to go describes in details the importance of the complement system (CS), autophagy, inflammasomes, and microbiota along with their targeting to manage sepsis. These systems are interconnected to each other, thus targeting one may affect the other. We are in an urgent need for a multi-targeting therapeutic approach for sepsis.

C23, an oligopeptide derived from cold-inducible RNA-binding protein, suppresses inflammation and reduces lung injury in neonatal sepsis

INTRODUCTION

Neonatal sepsis remains a leading cause of infant mortality. Cold-inducible RNA binding protein (CIRP) is an inflammatory mediator that induces TNF-α production in macrophages. C23 is a CIRP-derived peptide that blocks CIRP from binding its receptor. We therefore hypothesized that treatment with C23 reduces systemic inflammation and protects the lungs in neonatal sepsis.

METHODS

Sepsis was induced in C56BL/6 mouse pups (5-7 days) by intraperitoneal injection of adult cecal slurry (0.525 mg/g body weight, LD₁₀₀). One hour later pups received retroorbital injection of C23 (8 mg/kg) or vehicle (normal saline). Ten hours after sepsis induction, blood and tissues were collected for analysis.

RESULTS

C23 treatment resulted in a 58% and 69% reduction in serum levels of proinflammatory cytokines IL-6 and IL-1β, respectively, and a 40% and 45% reduction of AST and LDH, as compared to vehicle-treated septic pups. In the lungs, C23 treatment reduced expression of cytokines IL-6 and IL-1β by 78% and 74%. In addition, the mRNA level of neutrophil chemoattractants KC and MIP-2 was reduced by 84% and 74%, respectively. These results corresponded to a reduction in histologic lung injury score. Vehicle-treated pups scored 0.49 ± 0.19, while C23 treatment reduced scores to 0.29 ± 0.12 (p < 0.05; Max = 1). Apoptosis in the lungs, measured by TUNEL assay, was also decreased by 53% with C23 treatment (p < 0.05).

CONCLUSIONS

Inhibition of CIRP with C23 treatment is protective in septic neonatal mice as demonstrated by reduced inflammatory markers systemically and in the lung. Therefore, C23 has promising therapeutic potential in treatment of neonatal sepsis.

LEVEL OF EVIDENCE

Level I.

Executive Dysfunction Early Postnatal Biomarkers among Children Born Extremely Preterm

We evaluated the relationship between blood levels of inflammatory and neurotrophic proteins during the first postnatal month in 692 children born before the 28th week of gestation and executive function limitations among those 10-year olds who had an IQ ≥ 70. The measures of dysfunction were Z-scores ≤ -1 on the Differential Ability Scales-II working memory (WM) assessment) (N = 164), the NEPSY-II (A Developmental NEuroPSYchological Assessment-II) Inhibition-Inhibition assessment) (N = 350), the NEPSY-II Inhibition-Switching assessment) (N = 345), as well as a Z-score ≤ -1 on all three assessments (identified as the executive dysfunction composite (N = 104). Increased risks of the executive dysfunction composite associated with high concentrations of inflammatory proteins (IL-8, TNF-α, and ICAM-1) were modulated by high concentrations of neurotrophic proteins. This pattern of modulation by neurotrophins of increased risk associated with inflammation was also seen for the working memory limitation, but only with high concentrations of IL-8 and TNF-α, and the switching limitation, but only with high concentrations of ICAM-1. We infer that among children born extremely preterm, risks of executive function limitations might be explained by perinatal systemic inflammation in the absence of adequate neurotrophic capability.

Neutrophil extracellular traps (NETs) exacerbate severity of infant sepsis

Background

Neutrophil extracellular traps (NETs) are innate defense mechanisms that are also implicated in the pathogenesis of organ dysfunction. However, the role of NETs in pediatric sepsis is unknown.

Methods

Infant (2 weeks old) and adult (6 weeks old) mice were submitted to sepsis by intraperitoneal (i.p.) injection of bacteria suspension or lipopolysaccharide (LPS). Neutrophil infiltration, bacteremia, organ injury, and concentrations of cytokine, NETs, and DNase in the plasma were measured. Production of reactive oxygen and nitrogen species and release of NETs by neutrophils were also evaluated. To investigate the functional role of NETs, mice undergoing sepsis were treated with antibiotic plus rhDNase and the survival, organ injury, and levels of inflammatory markers and NETs were determined. Blood samples from pediatric and adult sepsis patients were collected and the concentrations of NETs measured.

Results

Infant C57BL/6 mice subjected to sepsis or LPS-induced endotoxemia produced significantly higher levels of NETs than the adult mice. Moreover, compared to that of the adult mice, this outcome was accompanied by increased organ injury and production of inflammatory cytokines. The increased NETs were associated with elevated expression of Padi4 and histone H3 citrullination in the neutrophils. Furthermore, treatment of infant septic mice with rhDNase or a PAD-4 inhibitor markedly attenuated sepsis. Importantly, pediatric septic patients had high levels of NETs, and the severity of pediatric sepsis was positively correlated with the level of NETs.

Conclusion

This study reveals a hitherto unrecognized mechanism of pediatric sepsis susceptibility and suggests that NETs represents a potential target to improve clinical outcomes of sepsis.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2407-8) contains supplementary material, which is available to authorized users.

Clinical features and antimicrobial susceptibility profiles of culture-proven neonatal sepsis in a tertiary children's hospital, 2013 to 2017

Neonatal sepsis (NS) remains a major cause of morbidity and mortality in neonates, but data on the etiology and antibiotic susceptibility patterns of pathogens are limited. The aim of this study was to analyze the clinical characteristics, risk factors, and the antibiotic susceptibility patterns of pathogenic microbes associated with NS at a tertiary children's hospital in Shanghai, China.Episodes of blood culture-proven sepsis in the neonatal intensive care unit (NICU) of Children's Hospital of Fudan University from January 2013 to August 2017 were retrospectively reviewed. Collected data included demographics, perinatal risk factors, clinical symptoms, laboratory values, microbiology results and their antimicrobial susceptibility. Data for early-onset neonatal sepsis (EONS) and late-onset neonatal sepsis (LONS) were compared.The 341 of 976 culture-positive cases were selected, including 161 EONS cases (47.21% of 341) and 180 LONS cases (52.79% of 341). 635 incomplete cases were excluded. There was significant difference in risk factors between the EONS group and LONS group including birth weight, gestational age, 1-minute Apgar score, respiratory support, and the use of peripherally insertion central catheter (PICC). Clinical symptoms such as fever, feeding intolerance, abdominal distension, and neonatal jaundice, and laboratory results such as hemoglobin and lymphocyte counts also showed between-group differences. Staphylococcus epidermidis (22.87%), Escherichia coli (9.68%), Alcaligenes xylosoxidans (9.38%) and Klebsiella pneumoniae (9.09%) remain the principal organisms responsible for neonatal sepsis. Most isolates of Gram-positive bacteria were sensitive to vancomycin, linezolid, minocycline and tigecycline, of which more than 90% were resistant to penicillin. Most isolates of Gram-negative bacteria were sensitive to amikacin and imipenem and resistant to ampicillin. Fungus was sensitive to antifungal agents. Better medical decisions, especially early detection and appropriate initial antimicrobial therapy can be made after understanding the different clinical features and pathogens of EONS and LONS.