Jean-Christophe Rozé

Valeur diagnostique des critères de suspicion d’infection néonatale précoce : bilan dix ans après les recommandations de l’Anaes

BACKGROUND Because clinical symptoms and biological markers are neither sensitive nor specific, newborns are frequently suspected of having an infection. In France, 30-50% of newborns are suspected of having early-onset sepsis (EOS) and many of them undergo laboratory tests and empirical antibiotic treatments while awaiting results. The aim of this study was to evaluate the diagnostic value of various suspicion criteria for EOS as recommended by the Anaes since 2002, and the value of umbilical cord blood procalcitonin (PCT), currently assayed in our maternity ward. MATERIAL AND METHODS This 4-year retrospective study in the CHU of Nantes included hospitalized newborns with suspected early neonatal infection. Infection status was established according to the Anaes definitions and clinical evolution. RESULTS The study included 2151 newborns. Among anamnestic criteria, only prematurity significantly increased the risk of EOS (relative risk of 3.1; 95% CI 1.4-7.0). The relative risk of infection for a symptomatic newborn was 12.2 (95% CI 4.9-30.2; P<0.0001). Laboratory test results were the most predictive criteria. The relative risk to be infected was 291.6 (95% CI 70.7-1,214.0; P<0.0001) with a blood cord PCT value>0.6 ng/L. The positive post-test probability was 28% (95% CI: 23-33) and the negative post-test probability was close to 0 (95% CI: 0-0). CONCLUSION Clinical criteria of postnatal life adaptation are more predictive of early-onset neonatal infection than anamnestic criteria are. The blood cord PCT value could be a helpful marker in the identification of infected newborns. PCT measured in umbilical cord blood could be included in a general algorithm in order to identify as soon as possible newborns with a high risk of EOS.

Hospital initiation of a vaccinal schedule improves the long-term vaccinal coverage of ex-preterm children.

Preterm infants are experiencing delays in receiving routine schedule vaccines. We evaluated up-to-date immunisation status of 602 preterm infants at 5 and 24 months for DTCoqPolioHib and pneumococcal conjugate vaccine (defined by 3 and 4 doses, respectively). At 5 months, 39% (CI 95% [35-43]) of children were up-to-date for DTCoqPolioHib and 22% (CI 95% [19-26]) for pneumococcal conjugate, while at 24 months 67% (CI 95% [64-71]) were up-to-date for DTCoqPolioHib and 36% (CI 95% [32-40]) for pneumococcal conjugate. After adjustment for gestational age, a primary vaccine before discharge remained linked with a better vaccinal coverage (p<.005, OR=5.0; CI 95% [2.9-8.5]).

MiRNA Analysis by Quantitative PCR in Preterm Human Breast Milk Reveals Daily Fluctuations of hsa-miR-16-5p

Background and Aims Human breast milk is an extremely dynamic fluid containing many biologically-active components which change throughout the feeding period and throughout the day. We designed a miRNA assay on minimized amounts of raw milk obtained from mothers of preterm infants. We investigated changes in miRNA expression within month 2 of lactation and then over the course of 24 hours. Materials and Methods Analyses were performed on pooled breast milk, made by combining samples collected at different clock times from the same mother donor, along with time series collected over 24 hours from four unsynchronized mothers. Whole milk, lipids or skim milk fractions were processed and analyzed by qPCR. We measured hsa-miR-16-5p, hsa-miR-21-5p, hsa-miR-146-5p, and hsa-let-7a, d and g (all -5p). Stability of miRNA endogenous controls was evaluated using RefFinder, a web tool integrating geNorm, Normfinder, BestKeeper and the comparative ΔΔCt method. Results MiR-21 and miR-16 were stably expressed in whole milk collected within month 2 of lactation from four mothers. Analysis of lipids and skim milk revealed that miR-146b and let-7d were better references in both fractions. Time series (5H-23H) allowed the identification of a set of three endogenous reference genes (hsa-let-7d, hsa-let-7g and miR-146b) to normalize raw quantification cycle (Cq) data. We identified a daily oscillation of miR-16-5p. Perspectives Our assay allows exploring miRNA levels of breast milk from mother with preterm baby collected in time series over 48–72 hours.

Measurement of oxygen uptake in newborn infants during assisted and spontaneous ventilation

Measurements of oxygen uptake (VO2) and CO2 output (VCO2) are useful in critically ill patients. However, VO2 is not routinely measured in intensive care during mechanical ventilation (MV) especially in premature newborns. The present study describes a new method of measuring VO2 and VCO2 using a double open circuit which accounts for gas leaks around the uncuffed tracheal tube. The accuracy of the method was assessed with N2 and CO2 infusion. In case of leaks, VO2 and VCO2 measurement was significantly underestimated by the simple circuit method. This underestimation was not present with double circuit method. Five preterm newborns were studied. VO2 and VCO2 using the double open circuit were compared with the classic simple circuit. During MV, the mean underestimation assessed by the difference between simple and double circuit measurement was -12% (range from 0 to -29%) for VO2 and -14% (range 0 to -26%) for VCO2.

Non-Invasive Exploration of Neonatal Gastric Epithelium by Using Exfoliated Epithelial Cells

Background & Aims In preterm infants, exfoliated gastric epithelial cells can be retrieved from aspirates sampled through the naso-gastric feeding tube. Our aims were to determine (1) whether the recovery of exfoliated cells is feasible at any time from birth through the removal of the nasogastric tube, (2) whether they can be grown in culture in vitro, and (3) whether the physiological state of exfoliated cells expressing H+/K+ -ATPases reflects that of their counterparts remaining in situ at the surface of the gastric epithelium in neonatal rat pups. Methods In infants, gastric fluid aspirates were collected weekly after birth or every 3 hours over 24-h periods, and related to clinical parameters (Biocollection PROG/09/18). In rat pups submitted to a single fasting/refeeding cycle, we explored circadian exfoliation with the cellular counter-parts in the gland. All samples were analyzed by confocal imaging and Enzyme-Linked Immunosorbent Assay. Results Epithelial cells were identified by microscopy using membrane-bound anti-H+/K+ ATPases antibody, assessed for nucleus integrity, and the expression of selected proteins (autophagy, circadian clock). On 34 infants, the H+/K+ -ATPase-positive cells were consistently found quiescent, regardless of gestational age and feeding schedule from day-5 of life to the day of removal of the naso-gastric tube. By logistic regression analysis, we did find a positive correlation between the intensity of exfoliation (cellular loss per sample) and the postnatal age (p<0.001). The H+/K+ ATPase-positive cells established in culture retained the expression of a biomarker of progenitor status (Pouf5F1-Oct4). In rat pups, the expression pattern of Survivin in H+/K+ ATPase-positive exfoliated cells paralleled that observed in cells remaining at the surface of the gastric gland. Conclusions Tracking parietal cells can improve clinical monitoring and understanding of the autophagic death via the phosphatidylinositol 3-kinase/Akt/survivin pathway.

SFP-02 – Pathologie infectieuse – Utilisation de la procalcitonine (PCT) aux urgences pédiatriques ; nécessité d’une prescription ciblée

La procalcitonine est un marqueur d’infection bacterienne maintenant valide chez l’adulte comme chez l’enfant. Son dosage fait depuis l’objet de nombreuses prescriptions puisqu’il est prescrit chez 10 % des enfants consultant dans notre service. Objectif Montrer le manque de performance de ce marqueur lorsqu’il est prescrit sans distinction dans toutes les situations de suspicions d’infections bacteriennes de l’enfant. Patients et Methodes Analyse retrospective d’une cohorte d’enfants ayant fait l’objet d’un dosage de PCT lors d’une consultation aux urgences pediatriques sur une periode de 2 mois. Les patients ont ete classes en 7 categories d’infections bacteriennes selon des definitions validees dans la litterature (Pyelonephrites, meningites,ORL,digestif,respiratoire,fievre isolee, syndrome grippal). Ont ete etablies des courbes ROC puis calcules la sensibilite, specificite et le rapport de vraisemblance (RV) de la PCT. Le seuil pathologique retenu etait 0.5 ng/ml Resultats 273 dossiers ont ete analyses. Toutes indications confondues, l’aire sous la courbe de la courbe ROC de la PCT est inferieure a celle de la CRP (0.75 ± 0.06 vs 0.81 ± 0.05 respectivement). L’association des 2 marqueurs par une analyse discriminante n’est pas plus performante que la CRP seule (0.82 ± 0.05 vs 0.81 ± 0.05). On retrouve pourtant de bonnes sensibilite, specificite et rapport de vraisemblance + en cas de fievre isolee : 100 ± 40%, 65.7 ± 14 % et 4.85 (IC 95 % : 3.04-7.7) respectivement, et de meningite : 100 ± 33 % et 100 ± 40 % respectivement. Ces parametres sont tres peu performants par contre en cas d’infections ORL ou digestives avec une sensibilite de 36 ± 22 et 40 ± 32%, une specificite de 73 ± 20 et 68 ± 14 % et un RV + de1.33 (IC95 % : 0.44-4) et 1.26 (IC95 % : 0.39-4.08) respectivement. A posteriori,42 % des prescriptions de PCT pour cette cohorte n’etaient pas justifiees. Conclusion La realisation d’un dosage de PCT doit etre reservee aux situations ou ce marqueur est connu comme discriminant. La prescription doit en etre ciblee et seniorisee afin d’eviter des derives d’utilisation deleteres pour tous.

SFP CO-71 - PCR automatisée et identification des infections néonatales à Streptococcus agalactiae

Les infections materno-foetales (IMF) a Streptococcus agalactiae (SGB) sont rares mais de pronostic grave. L’hemoculture peripherique est le test diagnostic principal, mais le resultat est peu sensible et tardif (24–48h). Des techniques de biologie moleculaire automatisee, rapides et sensibles ont ete validees sur ecouvillon dans le diagnostic du portage vaginal de SGB per partum. Objectif Etudier les performances diagnostiques de la PCR automatisee pour la detection du SGB dans le sang. Materiels et methodes Analyse par PCR automatisee (GENEXPERT®), comparativement a la culture, de 65 echantillons de sang de cordon inocules avec une quantite croissante de SGB ; puis du sang de cordon de 24 nouveau-nes suspects d’IMF a SGB et 74 temoins non infectes. Resultats principaux Detection par PCR de 10 2 CFU/mL et 10 6 CFU/mL dans 23,8% et 100% des cas respectivement. 4% des NN suspects d’IMF avaient une hemoculture positive a SGB alors que la PCR etait negative (SE et VPP 0, SP 100% (IC95% [99,97-100,02]), VPN 94,4% (IC95% [89,4–99,4]). Conclusions Les performances diagnostiques du GENEXPERT® sont insuffisantes pour mettre en evidence une bacteriemie antenatale a SGB sur sang de cordon. Cette technique doit etre perfectionnee afin de faciliter le diagnostic precoce d’IMF a SGB.