This is a narrative review about the mechanisms involved in bacterial sepsis in preterm infants, which is an illness with a high incidence, morbidity, and mortality. The role of the innate immune response and its relationship with oxidative stress in the pathogenesis are described as well as their potential implementation as early biomarkers. Moreover, we address the impact that all the mechanisms triggered by sepsis have on the dysbiosis and the changes on neonatal microbiota.

Fetal hemoglobin (HbF) has a higher affinity to oxygen than adult hemoglobin, allowing for a slower oxygen transfer to peripheral tissue, creating a microenvironment conducive to adequate fetal development in utero . However, most preterm infants receive packed red blood cell transfusions from adult donors leading to a drastic nonphysiological descent of circulating HbF. We hypothesized that this drop could enhance oxygen delivery to peripheral tissues generating a hyperoxic pro-oxidant environment. To investigate this, we assessed differences in oxidative stress biomarkers determined in urine samples in a cohort of 56 preterm infants born <32 weeks' gestation. Median oxidative stress biomarkers were compared between patients with circulating HbF above or below median HbF levels using Wilcoxon rank sum test. Oxidative stress biomarkers were significantly higher in the group of patients with lower levels of HbF. This study provides the initial evidence indicating elevated levels of oxidative stress biomarkers in preterm neonates with lower HbF levels. Based on the results, we hypothesize that HbF may contribute to preventing free radical-associated conditions during the newborn period. Antioxid. Redox Signal. 40, 453–459.

Background: Skin antisepsis is one of the most important bundle measures to decrease central line-related bloodstream infections (CRBSIs). However, in the neonatal population, the use of alcoholic chlorhexidine is limited by the risk of skin lesions. Objective: We hypothesised that skin antisepsis with alcohol-based 2% chlorhexidine instead of aqueous 2% chlorhexidine could reduce the incidence of CRBSI without increasing skin complications. Design: We conducted a double cohort study comparing two periods of 3 years, first using aqueous and second using alcohol-based chlorhexidine, leaving a 1-year washout interval between them. In extremely preterm infants, aqueous chlorhexidine was used during the first week of life in both periods. Results: A total of 1783 patients and 2493 episodes of central line catheter were analysed. There were no statistically significant differences in clinical and demographic data from infants in both periods. There was a significant reduction in the pooled incidence density of CRBSI in the second compared with the first period (4.03 vs 9.05 episodes/1000 central line days, OR 0.45 (95% CI 0.29 to 0.68)). The overall absolute risk reduction was 0.039 (95% CI 0.023 to 0.056) and the number needed to treat was 25. A similar but not significant reduction of the small number of CRBSI was observed in extremely preterm infants within the first week of life OR 0.43 (95% CI 0.134 to 1.379). No statistically significant differences in skin lesions were observed between periods, making erythema the most common injury(5.1% vs 4.2%). Relevance: Alcohol-based 2% chlorhexidine as a skin antiseptic could reduce the incidence of CRBSI in neonates without producing an increase in skin lesions.

Extreme preterm infants (60%) and lower (<30%) initial FiO₂. Recent evidence and meta-analyses have underscored the predictive value for survival and/or relevant clinical outcomes of the Apgar score and the achievement of arterial oxygen saturation measured by pulse oximetry ≥85% at 5 minutes after birth. New clinical trials comparing higher versus lower initial FiO₂ have been launched aiming to optimize postnatal stabilization of extreme preterm while avoiding adverse effects of hypoxemia or hyperoxemia.