Summary Preterm birth and infectious diseases are the most common causes of neonatal and early childhood deaths worldwide. The rates of preterm birth have increased over recent decades and account ...for 11% of all births worldwide. Preterm infants are at significant risk of severe infection in early life and throughout childhood. Bacteraemia, inflammation, or both during the neonatal period in preterm infants is associated with adverse outcomes, including death, chronic lung disease, and neurodevelopmental impairment. Recent studies suggest that bacteraemia could trigger cerebral injury even without penetration of viable bacteria into the CNS. Here we review available evidence that supports the concept of a strong association between bacteraemia, inflammation, and cerebral injury in preterm infants, with an emphasis on the underlying biological mechanisms, clinical correlates, and translational opportunities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Preterm infants are at increased risk for invasive neonatal bacterial infections.
, a ubiquitous skin commensal, is a major cause of late-onset neonatal sepsis, particularly in high-resource ...settings. The vulnerability of preterm infants to serious bacterial infections is commonly attributed to their distinct and developing immune system. While developmentally immature immune defences play a large role in facilitating bacterial invasion, this fails to explain why only a subset of infants develop infections with low-virulence organisms when exposed to similar risk factors in the neonatal ICU. Experimental research has explored potential virulence mechanisms contributing to the pathogenic shift of commensal
strains. Furthermore, comparative genomics studies have yielded insights into the emergence and spread of nosocomial
strains, and their genetic and functional characteristics implicated in invasive disease in neonates. These studies have highlighted the multifactorial nature of
traits relating to pathogenicity and commensalism. In this review, we discuss the known host and pathogen drivers of
virulence in neonatal sepsis and provide future perspectives to close the gap in our understanding of
as a cause of neonatal morbidity and mortality.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Supplementation with probiotics in preterm infants reduces necrotizing enterocolitis and sepsis. Bovine lactoferrin is a promising supplement that may further reduce disease burden, but its effects ...on probiotic bacteria in human breast milk has not been evaluated. We aimed to characterise the antimicrobial activity of bovine and human lactoferrin in human breast milk against probiotics and typical neonatal sepsis pathogens. Lactoferrin levels were determined by enzyme linked immunosorbent assay in fresh and pasteurised human breast milk. The neonatal pathogens Staphylococcus epidermidis and Escherichia coli, and the probiotic Bifidobacterium breve strain M-16V were cultured in human breast milk or infant formula in the presence or absence of clinically relevant doses of bovine or human lactoferrin. Standard microbiological methods were used to determine the effects of lactoferrin on bacterial growth. Unpasteurised human breast milk contained significantly higher lactoferrin levels and resulted in superior inhibition of pathogenic bacterial growth compared to infant formula and pasteurised human breast milk. Human lactoferrin was significantly more effective at inhibiting bacterial growth, when compared to bovine lactoferrin. Supplementation with human lactoferrin or high dose bovine lactoferrin inhibited growth of the probiotic strain B. breve M-16V in pasteurised human breast milk. Although unpasteurised human breast milk and human lactoferrin had the greatest antimicrobial activity against all bacterial species tested, higher doses of bovine lactoferrin also showed activity against B. breve and. S. epidermidis. This study suggests that simultaneous administration of lactoferrins and probiotics may affect colonisation with probiotic bacteria, warranting further investigations.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Deficiencies in innate immune responses may contribute to the increased susceptibility to infection in preterm infants. In vivo cytokine profiles in response to sepsis in very preterm infants are not ...fully understood.
To characterise plasma pro- and anti-inflammatory cytokine concentrations and pre-defined ratios in very preterm infants with late-onset sepsis (LOS).
In this observational study, peripheral blood samples were collected at the time of evaluation for suspected LOS from 31 preterm infants (<30 weeks gestational age). Plasma cytokine concentrations were determined by 12-plex immunoassay.
IL-10, IFN-γ, IL-12p70, IP-10, IL-6 and CCL2 were elevated in the majority infants with LOS (n = 12) compared to those without LOS (n = 19). There was no difference in TNF-α, IL-1β, IL-17AF, IL-8 and IL-15 concentrations between groups. IL-10/TNF-α ratios were increased, while CCL2/IL-10 and IL-12p70/IL-10 ratios were decreased in infants with LOS compared to those without.
Very preterm infants have a marked innate inflammatory response at the time of LOS. The increase in IL-10/TNF-α ratio may indicate early immune hypo-responsiveness. Longitudinal studies with a larger number of participants are required to understand immune responses and clinical outcomes following LOS in preterm infants.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Overuse of empirical intravenous antibiotics in neonates in high-income countries (HICs) is well documented. The Kaiser Permanente neonatal early-onset sepsis (EOS) calculator is an evidence-based ...sepsis risk assessment tool that has demonstrated potential to reduce antibiotic usage in this population. The incidence of early-onset sepsis in most HICs is 0.4–0.8 per 1000 live births. The objective was to evaluate the calculator's impact on antibiotic rates and length of stay in a regional level II Special Care Nursery.
A single-centre retrospective cohort study compared antibiotic administration rates in the first 72 h in neonates ≥35 weeks gestation born during two 6-month periods in 2019 (pre-EOS calculator) and 2021 (post-EOS calculator). Electronic and paper case records were accessed to capture data. Continuous data were summarised using mean and standard deviation, and categorical data were summarized using frequency distributions. There were 951 (2019) and 1129 (2021) infants born during the study periods.
Following implementation of the calculator, antibiotic exposure decreased from 13.7% to 4.7% of all neonates without reported negative outcomes. Mean length of stay for neonates born across the two periods decreased from 2.38 to 2.13 days. Indications for antibiotic use shifted more towards clinical condition and away from obstetric risk factors. There were no culture-proven cases of sepsis or readmissions with EOS in either period.
Implementation of the EOS calculator significantly reduced exposure to antibiotics, without adverse outcomes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Neonates, particularly those born prematurely, are exquisitely vulnerable to life-threatening infections. This increased susceptibility to infection is maintained into childhood. Despite the ...considerable human and economic cost of infection-related neonatal morbidity and mortality, the mechanisms underlying this heightened susceptibility are only partly understood. It is increasingly recognised that innate immune responses are key to the protection against infection early in life, and emerging data suggest that such responses are deficient in the newborn and especially in preterm infants. Here we review the current understanding of the maturation of the innate immune response in human neonates highlighting the clinical relevance and possible avenues for therapeutic intervention.
Summary Background Reduced gestational age and low birthweight are associated with an increased risk of neonatal infections. However, the long-term risk of infection, especially in late preterm ...infants or those at near-normal birthweight, is unknown. We estimated whether rates of infection-related admissions to hospital for children in Western Australia were associated with age, gestational age, birthweight, and birth length. Methods We did a population-based, data-linkage study using total-linked, registry data from the Western Australia Birth Register of all liveborn, non-Indigenous Australian singleton births recorded from Jan 1, 1980, to Dec 31, 2010. We followed up individuals from birth-related hospital discharge to age 18 years, death, or end of 2010, and linked to data about subsequent admissions to hospital or death registrations. Gestational age was assessed from both the last menstrual period and from estimates based on ultrasonography. We categorised birthweight by 500 g bands and birth length by 5 cm bands, and approximated the reference ranges for both to the 50th percentile. Because size at birth and gestational age are strongly associated, we calculated Z scores for gestational-specific and sex-specific birthweight, birth length, and ponderal index. Our primary outcomes were the number and type of infection-related admissions to hospital. We used multilevel negative binomial regression to generate rate ratios (RR) for such admissions, identified by codes from the International Classification of Diseases, versions 9 and 10-AM. We adjusted the RRs for maternal age at delivery, birth year, birth season, parity, sex, 5-min Apgar score, delivery method, socioeconomic status, and bronchopulmonary dysplasia. Findings Of 719 311 liveborn singletons included in the analysis and followed up for 8 824 093 person-years, 365 867 infection-related admissions to hospital occurred for 213 683 (30%) children. Of the 719 311 children included in the analysis, 137 124 (19%) had one infection-related admission to hospital, 43 796 (6%) had two, 16 679 (2%) had three, and 16 084 (2%) had four or more. The 365 867 admissions to hospital included a diagnosis of infection of the upper respiratory tract for 174 653 (48%), the lower respiratory tract for 74 297 (20%), the gastrointestinal tract for 44 755 (12%), and a viral infection for 37 213 (10%). Infection-related rates of admissions to hospital increased by 12% for each week reduction in gestational age less than 39–40 weeks (RR 1·12, 95% CI 1·12–1·13), by 19% for each 500 g reduction in birthweight less than 3000–3500 g (1·19, 1·18–1·21), and by 41% for each 5 cm reduction in birth length less than 45–50 cm (1·41, 1·38–1·45). Gestational age-specific and sex-specific birthweight Z scores lower than the 25th to 50th percentile and birth length Z scores lower than the 10th to 25th percentile were associated with increased rates of infection-related admissions to hospital (eg, 1st–5th percentile RR 1·15, 95% CI 1·12–1·19, and 1·11, 1·07–1·14, respectively). Ponderal index Z scores lower than the 25th to 50th percentile were also associated with increased rates of infection-related admissions (eg, 1st–5th percentile RR 1·08, 95% CI 1·04–1·12). A gestational age of 41 weeks or later, a birthweight or birth length Z score above the 50th percentile, or a ponderal index Z score between the 75th and 95th percentile, were associated with modestly reduced rates of infection-related admissions to hospital. Interpretation Children who were born with reduced gestational age, birthweight, and birth length have persistently increased rates of infection-related admissions to hospital until age 18 years. Pregnancy outcomes should be optimised to prevent infection occurring in this population, especially in resource-limited settings where suboptimum intrauterine growth and moderate prematurity are common. Funding Australian National Health and Medical Research Council.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Antibiotic exposure at the beginning of life can lead to increased antimicrobial resistance and perturbations of the developing microbiome. Early-life microbiome disruption increases the risks of ...developing chronic diseases later in life. Fear of missing evolving neonatal sepsis is the key driver for antibiotic overtreatment early in life. Bias (a systemic deviation towards overtreatment) and noise (a random scatter) affect the decision-making process. In this perspective, we advocate for a factual approach quantifying the burden of treatment in relation to the burden of disease balancing antimicrobial stewardship and effective sepsis management.
Composition of leukocyte populations in the first month of life remains incompletely characterised, particularly in preterm infants who go on to develop late-onset sepsis (LOS).
To characterise and ...compare leukocyte populations in preterm infants with and without LOS during the first month of life.
Single-centre prospective observational cohort study.
Infants born <30 weeks gestational age (GA).
Peripheral blood samples were collected at 1, 7, 14, 21 and 28 days of life. Leukocyte populations were characterised using 5-fluorophore-6-marker flow cytometry. Absolute leukocyte counts and frequency of total CD45+ leukocytes of each population were adjusted for GA, birth weight z-scores, sex and total leukocyte count.
Of 119 preterm infants enrolled, 43 (36%) had confirmed or clinical LOS, with a median onset at 13 days (range 6-26). Compared to infants without LOS, the adjusted counts and frequency of neutrophils, basophils and non-cytotoxic T lymphocytes were generally lower and immature granulocytes were higher over the first month of life in infants who developed LOS. Specific time point comparisons identified lower adjusted neutrophil counts on the first day of life in those infants who developed LOS more than a week later, compared to those without LOS, albeit levels were within the normal age-adjusted range. Non-cytotoxic T lymphocyte counts and/or frequencies were lower in infants following LOS on days 21 and 28 when compared to those who did not develop LOS.
Changes in non-cytotoxic T lymphocytes occurred following LOS suggesting sepsis-induced immune suppression.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Machine learning (ML) algorithms are powerful tools that are increasingly being used for sepsis biomarker discovery in RNA-Seq data. RNA-Seq datasets contain multiple sources and types of noise ...(operator, technical and non-systematic) that may bias ML classification. Normalisation and independent gene filtering approaches described in RNA-Seq workflows account for some of this variability and are typically only targeted at differential expression analysis rather than ML applications. Pre-processing normalisation steps significantly reduce the number of variables in the data and thereby increase the power of statistical testing, but can potentially discard valuable and insightful classification features. A systematic assessment of applying transcript level filtering on the robustness and stability of ML based RNA-seq classification remains to be fully explored. In this report we examine the impact of filtering out low count transcripts and those with influential outliers read counts on downstream ML analysis for sepsis biomarker discovery using elastic net regularised logistic regression, L1-reguarlised support vector machines and random forests. We demonstrate that applying a systematic objective strategy for removal of uninformative and potentially biasing biomarkers representing up to 60% of transcripts in different sample size datasets, including two illustrative neonatal sepsis cohorts, leads to substantial improvements in classification performance, higher stability of the resulting gene signatures, and better agreement with previously reported sepsis biomarkers. We also demonstrate that the performance uplift from gene filtering depends on the ML classifier chosen, with L1-regularlised support vector machines showing the greatest performance improvements with our experimental data.
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