Neonatal infections due to multi-resistant strains: Epidemiology, current treatment, emerging therapeutic approaches and prevention.

Severe infections represent the main cause of neonatal mortality accounting for more than one million neonatal deaths worldwide every year. Antibiotics are the most commonly prescribed medications in neonatal intensive care units. The benefits of antibiotic therapy when indicated are clearly enormous, but the continued and widespread use of antibiotics has generated over the years a strong selective pressure on microorganisms, favoring the emergence of resistant strains. Health agencies worldwide are galvanizing attention toward antibiotic resistance in gram-positive and gram-negative bacteria. Infections in neonatal units due to multidrug and extensively multidrug resistant bacteria are rising and are already seriously challenging antibiotic treatment options. While there is a growing choice of agents against multi-resistant gram-positive bacteria, new options for multi-resistant gram-negative bacteria in the clinical practice have decreased significantly in the last 20 years making the treatment of infections caused by multidrug-resistant pathogens challenging mostly in neonates. Treatment options are currently limited and will be some years before any new treatment for neonates become available for clinical use, if ever. The aim of the review is to highlight the current knowledge on antibiotic resistance in the neonatal population, the possible therapeutic choices, and the prevention strategies to adopt in order to reduce the emergency and spread of resistant strains.

Serum Calprotectin: A Potential Biomarker for Neonatal Sepsis.

INTRODUCTION: The correct diagnosis of neonatal sepsis is a relevant problem because sepsis is one of the most important causes of neonatal morbidity, mortality, and prolonged hospital stay. Calprotectin is an antimicrobial, calcium and zinc binding heterocomplex protein that could be used as a nonspecific marker for activation of granulocytes and mononuclear phagocytes. Calprotectin has been proposed for the diagnosis of inflammatory conditions. Our aim is to study serum calprotectin as a biomarker for neonatal sepsis diagnosis. METHODS: 41 (20 females, 21 males) infants who underwent blood culture due to suspected sepsis were enrolled in the study. Serum calprotectin was measured by a commercial ELISA assay (Calprest, Eurospital, Trieste, Italy). Statistical analysis was performed using the statistical software package Stata 13.1 (Stata Corporation, College Station, Texas, USA). RESULTS: 8 neonates (19.51%) showed sepsis with positive culture and 33 (80.49%) showed suspected sepsis. The optimal cut-off for calprotectin is 2.2 µg/mL with a sensitivity of 62.5% and a specificity of 69.7%. CONCLUSIONS: Calprotectin may be considered a promising early, sensitive, specific marker of sepsis thanks to the importance of calprotectin in defense mechanisms and physiological functions of the immune system.

Cerebral Oxygenation, Superior Vena Cava Flow, Severe Intraventricular Hemorrhage and Mortality in 60 Very Low Birth Weight Infants.

BACKGROUND: Brain vulnerability in the critically ill preterm newborn may be related to the burden of cerebral hypoxygenation and hypoperfusion during the immediate postnatal period. OBJECTIVE: We determined the association between adverse outcomes [death or high grade intraventricular hemorrhage (IVH)] and continuous cerebral tissue oxygen saturation (rSO2), superior vena cava flow (SVCf) and cerebral fractional oxygen extraction (CFOE) in very low birth weight (VLBW) infants during the first 48 h of life. METHODS: We studied a prospective cohort of 60 VLBW infants admitted to our neonatal intensive care unit within the first 6 h of life between March 2010 and June 2012. rSO2 (expressed as a number of summary measures) was continuously monitored with near-infrared spectroscopy (INVOS 5100 Somanetic) during the first 48 h of life, SCVf was measured at 4-6, 12, 24 and 48 h after birth, and CFOE was calculated. RESULTS: The mean gestational age was 27.9 (SD 2.39); 8 infants died (13.3%) and 7 developed IVH grade III-IV: 1 in the alive group and 6 in the deceased group (p < 0.001). The odds ratio for death was 1.08 (95% CI: 1.015-1.15, p = 0.016) for each 10 periods of rSO2 values <40% in the first 48 h, and 4.2 (95% CI: 1.27-14.05, p = 0.019) for SVCf values <40 ml/kg/min. Among alive babies, mean CFOE decreased at 24, 36 and 48 h; among deceased babies it did not (p < 0.001). In the multivariate analyses, these results retained significance. CONCLUSIONS: Both rSO2 ≤40% and SVCf <40 ml/kg/min independently increase the risk of death. The trend in CFOE supports the ischemic-hypoperfusion hypothesis as a mechanism for cerebral damage.

Expression and function of toll-like receptors in human circulating endothelial colony forming cells.

Mature endothelial cells are known to sense microbial products through toll-like receptors (TLRs), a family of membrane proteins which serve as pathogen recognition and signaling elements; however, there are limited data in the literature about the expression and function of TLRs in human circulating endothelial colony forming cells (ECFCs), which are considered the most likely endothelial precursors. We expanded and differentiated in vitro umbilical cord blood (UCB) and adult peripheral blood (PB) ECFCs and studied the expression of TLR1 to TLR10 mRNA by qPCR analysis, and we further characterized TLR function in ECFCs through functional assays including in vitro ECFC growth and differentiation, assessment of cytokine production, and measurement of intracellular Ca(2+) signals. Both UCB- and PB-ECFCs had detectable mRNA levels of all the TLRs from 1 to 10; TLR4, a sensor of Gram-negative bacterial lipopolysaccharide (LPS), had a higher level compared to other TLRs. Exposure to LPS induced cytokine production, although with less efficiency compared to PB-mononuclear cells. However, no effect of LPS was seen on ECFC growth and differentiation, and no increase in intracellular Ca(2+) concentrations, which is essential for ECFC proliferation, was observed after exposure to increasing amounts of LPS. Our data show that all TLRs from 1 to 10 are constitutively expressed in ECFCs, and suggest that TLR4 is functional in ECFCs, but its activation through its ligand LPS does not affect ECFC growth and differentiation.

Global perfusion assessment and tissue oxygen saturation in preterm infants: where are we?

Near infrared spectroscopy (NIRS) monitoring is a new challenge for clinicians who deal with early detection of dangerous hypoperfusion in the brain, as well as in splanchnic and renal districts in critically ill preterm infants. Previous studies performed on infants and children with congenital heart disease, demonstrated the efficacy of this non-invasive method in managing hypoperfusive states pre, post and during cardiac surgery. Its use has improved post surgery outcome. NIRS monitoring has been used also to assess therapeutic intervention utility. Early identification of silent hypoperfusion has made NIRS use in preterm infants very interesting for neonatologists, especially where other techniques have failed. In this work, literature on this topic has been carefully examined, particularly the "two site NIRS" use in preterm infants, to evaluate how regional splanchnic oxygen saturation changes, both in physiological events, such as enteral feeding and in hemodynamic disorders, that occur in patients with significant patent ductus and in hypoperfusive states that lead to necrotizing enterocolitis.

Human milk feeding prevents retinopathy of prematurity (ROP) in preterm VLBW neonates.

BACKGROUND: Retinopathy of prematurity (ROP) is a multifactorial disease, but little is known about its relationships with neonatal nutritional policies. Human, maternal milk is the best possible nutritional option for all premature infants, including those at high risk for severe complications of prematurity, such as ROP. OBJECTIVE: This is a secondary analysis of data collected during two multicenter RCTs performed consecutively (years 2004 through 2008) by a network of eleven tertiary NICUs in Italy. The two trials aimed at assessing effectiveness of fluconazole prophylaxis (Manzoni et al., N Engl J Med 2007 Jun 14;356(24):2483-95), and of bovine lactoferrin supplementation (Manzoni et al., JAMA 2009 Oct 7;302(13):1421-8), in prevention of invasive fungal infection, and of late-onset sepsis in VLBW infants, respectively. We tested the hypothesis that exclusive feeding with fresh maternal milk may prevent ROP of any stage - as defined by the ETROP study - in VLBW neonates, compared to formula feeding. METHODS: We analyzed the database from both trials. Systematic screening for detection of ROP was part of the protocol of both studies. The definition of threshold ROP was as defined by the ETROP study. Univariate analysis was performed to look for significant associations between ROP and several possible associated factors, and among them, the type of milk feeding (maternal milk or formula for preterms). When an association was indicated by p < 0.05, multiple logistic regression was used to determine the factors significantly associated with ROP. RESULTS: In both trials combined, 314 infants received exclusively human maternal milk (group A), and 184 a preterm formula because their mothers were not expected to breastfeed. The clinical, demographical and management characteristics of the neonates did not differ between the two groups, particularly related to the presence of the known risk factors for ROP. Overall, ROP incidence (any stage) was significantly lower in infants fed maternal milk (11 of 314; 3.5%) as compared to formula-fed neonates (29 of 184; 15.8%) (RR 0.14; 95% CI 0.12-0.62; p = 0.004). The same occurred for threshold ROP (1.3% vs. 12.3%, respectively; RR 0.19; 95% CI 0.05-0.69; p = 0.009). At multivariate logistic regression controlling for potentially confounding factors that were significantly associated to ROP (any stage) at univariate analysis (birth weight, gestational age, days on supplemental oxygen, systemic fungal infection, outborn, hyperglycaemia), type of milk feeding retained significance, human maternal milk being protective with p = 0.01. CONCLUSIONS: Exclusive human, maternal milk feeding since birth may prevent ROP of any stage in VLBW infants in the NICU.