Laurent Ferraris

Oral supplementation with probiotics in very-low-birth-weight preterm infants: a randomized, double-blind, placebo-controlled trial

BACKGROUND Although recent reports suggest that supplementation with probiotics may enhance intestinal function in premature infants, the mechanisms are unclear, and questions remain regarding the safety and efficacy of probiotics in extremely low-birth-weight infants. OBJECTIVE The objective was to evaluate the efficacy of probiotics on the digestive tolerance to enteral feeding in preterm infants born with a very low or extremely low birth weight. DESIGN In a bicentric, double-blind, randomized controlled clinical trial that was stratified for center and birth weight, 45 infants received enteral probiotics (Bifidobacterium longum BB536 and Lactobacillus rhamnosus GG; BB536-LGG) and 49 received placebo. The primary endpoint was the percentage of infants receiving >50% of their nutritional needs via enteral feeding on the 14th day of life. A triangular test was used to perform sequential analysis. RESULTS The trial was discontinued after the fourth sequential analysis concluded a lack of effect. The primary endpoint was not significantly different between the probiotic (57.8%) and placebo (57.1%) groups (P = 0.95). However, in infants who weighed >1000 g, probiotic supplementation was associated with a shortening in the time to reach full enteral feeding (P = 0.04). Other than colonization by the probiotic strains, no alteration in the composition of intestinal microbiota or changes in the fecal excretion of calprotectin was observed. No colonization by probiotic strains was detected in infants who weighed < or =1000 g, presumably because of more frequent suspensions of enteral feeding, more courses of antibiotic treatment, or both. CONCLUSIONS Supplementation with BB536-LGG may not improve the gastrointestinal tolerance to enteral feeding in very-low-birth-weight infants but may improve gastrointestinal tolerance in infants weighing >1000 g. This trial was registered at clinicaltrials.gov as NCT 00290576.

Conditions of bifidobacterial colonization in preterm infants : A prospective analysis

Background: Premature birth results in a delayed and abnormal qualitative pattern of gut colonization. This abnormal pattern is thought to affect intestinal development and contribute to a higher risk of gastrointestinal infectious diseases such as neonatal necrotizing enterocolitis (NEC). In particular, bifidobacteria are thought to play a major role. We therefore studied bifidobacterial colonization in preterm infants during the first month of life. Patients and Methods: Fecal samples were prospectively analyzed in 52 infants born at a gestational age ranging from 30 to 35 weeks fed with a preterm formula alone and, in 18, with their mothers milk. Fecal samples were collected twice per week during the hospital stay. Bifidobacterial colonization was analyzed with culture and a molecular method. Results: Bifidobacterial colonization occurred in 18 infants at a median age of 11 days, always greater than the corrected mean gestational age of 35.4 weeks (SD, 0.9) and greater than 34 weeks for 16 of 18. Colonization by bifidobacteria was affected by neither birthweight nor mode of delivery nor antibiotics given to the mother or infant. In contrast, birth gestational age had a significant impact on colonization by bifidobacteria (P < 0.05), which always occurred in children born at a birth gestational age greater than 32.9 weeks (P < 0.05). Conclusions: Birth gestational age seems to act as a major determinant of bifidobacterial colonization in the premature infant, suggesting the role of gut maturation, a finding that should probably be taken into account in manipulations of the gut flora aimed at reducing NEC.

Investigation of the intestinal microbiota in preterm infants using different methods.

Modifications in microbial colonization of the human gut are believed to affect intestinal homeostasis and increase the risk of gastrointestinal diseases. The present study examined different methods for investigating the dynamic characterization of the intestinal microbiota in preterm infants. Fecal samples were collected weekly from ten preterm infants during their stay in a neonatal intensive care unit. The infants had a mean gestational age of 29 weeks (range: 28-32 weeks) and a mean birth weight of 1233g (range: 935-1450g). Bacterial colonization was assessed using conventional culture techniques and molecular biological methods. More specifically, the recently developed denaturing high performance liquid chromatography (dHPLC) technique was compared to established methods such as temporal temperature gradient gel electrophoresis (TTGE) and rRNA gene library sequencing. Our results indicate that the gastrointestinal tract of preterm infants, born at a gestational age of less than 33 weeks, has a low biodiversity of mainly, culturable bacteria. Finally, dHPLC was evaluated in terms of speed, labor and sensitivity for its use as a tool to analyze microbial colonization in preterm infants. We found that this technique provided major improvements over gel-based fingerprinting methods, such as TTGE, that are commonly used for studying microbial ecology. As such, it may become a common analytical tool for this purpose.

A fermented formula in pre-term infants: clinical tolerance, gut microbiota, down-regulation of faecal calprotectin and up-regulation of faecal secretory IgA

Intestinal bacterial colonisation in pre-term infants is delayed compared with full-term infants, leading to an increased risk of gastrointestinal disease. Modulation of colonisation through dietary supplementation with probiotics or prebiotics could decrease such a risk. The present study evaluated clinical tolerance, the effects on gut microbiota, and inflammatory and immunological mucosal responses to an infant formula adapted for pre-term infants that included in its manufacturing process a fermentation step with two probiotic strains, Bifidobacterium breve C50 and Streptococcus thermophilus 065, inactivated by heat at the end of the process. A total of fifty-eight infants (gestational age: 30-35 weeks), fed either the fermented pre-term formula or a standard pre-term formula, were followed up during their hospital stay. Clinical tolerance, faecal microbiota using a culture and a culture-independent method (temporal temperature gel electrophoresis), faecal calprotectin and secretory IgA were analysed weekly. No difference was observed regarding anthropometric data and digestive tolerance, except for abdominal distension, the incidence of which was lower in infants fed the fermented formula for 2 weeks. Bacterial colonisation was not modified by the type of feeding, particularly for bifidobacteria. Faecal calprotectin was significantly lower in infants fed the fermented formula for 2 weeks, and secretory IgA increased with both mothers milk and the fermented formula. The fermented formula was well tolerated and did not significantly modulate the bacterial colonisation but had benefits on inflammatory and immune markers, which might be related to some features of gastrointestinal tolerance.

Clostridia in Premature Neonates' Gut: Incidence, Antibiotic Susceptibility, and Perinatal Determinants Influencing Colonization

Background Although premature neonates (PN) gut microbiota has been studied, data about gut clostridial colonization in PN are scarce. Few studies have reported clostridia colonization in PN whereas Bacteroides and bifidobacteria have been seldom isolated. Such aberrant gut microbiota has been suggested to be a risk factor for the development of intestinal infections. Besides, PN are often treated by broad spectrum antibiotics, but little is known about how antibiotics can influence clostridial colonization based on their susceptibility patterns. The aim of this study was to report the distribution of Clostridium species isolated in feces from PN and to determine their antimicrobial susceptibility patterns. Additionally, clostridial colonization perinatal determinants were analyzed. Results Of the 76 PN followed until hospital discharge in three French neonatal intensive care units (NICUs), 79% were colonized by clostridia. Clostridium sp. colonization, with a high diversity of species, increased throughout the hospitalization. Antibiotic courses had no effect on the clostridial colonization incidence although strains were found susceptible (except C. difficile) to anti-anaerobe molecules tested. However, levels of colonization were decreased by either antenatal or neonatal (during more than 10 days) antibiotic courses (p = 0.006 and p = 0.001, respectively). Besides, incidence of colonization was depending on the NICU (p = 0.048). Conclusion This study shows that clostridia are part of the PN gut microbiota. It provides for the first time information on the status of clostridia antimicrobial susceptibility in PN showing that strains were susceptible to most antibiotic molecules. Thus, the high prevalence of this genus is not linked to a high degree of resistance to antimicrobial agents or to the use of antibiotics in NICUs. The main perinatal determinant influencing PN clostridia colonization appears to be the NICU environment.

New selective medium for selection of bifidobacteria from human feces.

This work reports an alternative selective medium for reliable and efficient isolation of human fecal bifidobacteria. It uses a base commercially available, does not need pH adjustment and can be autoclaved with its additives. It provides a useful alternative for fecal bifidobacteria isolation.

Fecal Calprotectin Excretion in Preterm Infants during the Neonatal Period

Background Fecal calprotectin has been proposed as a non-invasive marker of intestinal inflammation in inflammatory bowel disease in adults and children. Fecal calprotectin levels have been reported to be much higher in both healthy full-term and preterm infants than in children and adults. Objective To determine the time course of fecal calprotectin (f-calprotectin) excretion in preterm infants from birth until hospital discharge and to identify factors influencing f-calprotectin levels in the first weeks of life, including bacterial establishment in the gut. Methodology F-calprotectin was determined using an ELISA assay in 147 samples obtained prospectively from 47 preterm infants (gestational age, and birth-weight interquartiles 27–29 weeks, and 880–1320 g, respectively) at birth, and at 2-week intervals until hospital discharge. Principal Findings Although median f-calprotectin excretion was 138 µg/g, a wide range of inter- and intra-individual variation in f-calprotectin values (from day 3 to day 78) was observed (86% and 67%, respectively). In multivariate regression analysis, f-calprotectin correlated negatively with ante and per natal antibiotic treatment (p = 0.001), and correlated positively with the volume of enteral feeding (mL/kg/d) (p = 0.009), the need to interrupt enteral feeding (p = 0.001), and prominent gastrointestinal colonization by Clostridium sp (p = 0.019) and Staphylococcus sp (p = 0.047). Conclusion During the first weeks of life, the high f-calprotectin values observed in preterm infants could be linked to the gut bacterial establishment.

16S rRNA gene sequencing, multilocus sequence analysis, and mass spectrometry identification of the proposed new species “Clostridium neonatale”

ABSTRACT In 2002, an outbreak of necrotizing enterocolitis in a Canadian neonatal intensive care unit was associated with a proposed novel species of Clostridium, “Clostridium neonatale.” To date, there are no data about the isolation, identification, or clinical significance of this species. Additionally, C. neonatale has not been formally classified as a new species, rendering its identification challenging. Indeed, the C. neonatale 16S rRNA gene sequence shows high similarity to another Clostridium species involved in neonatal necrotizing enterocolitis, Clostridium butyricum. By performing a polyphasic study combining phylogenetic analysis (16S rRNA gene sequencing and multilocus sequence analysis) and phenotypic characterization with mass spectrometry, we demonstrated that C. neonatale is a new species within the Clostridium genus sensu stricto, for which we propose the name Clostridium neonatale sp. nov. Now that the status of C. neonatale has been clarified, matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) can be used for better differential identification of C. neonatale and C. butyricum clinical isolates. This is necessary to precisely define the role and clinical significance of C. neonatale, a species that may have been misidentified and underrepresented during previous neonatal necrotizing enterocolitis studies.

Antimicrobial susceptibility and resistance determinants of Clostridium butyricum isolates from preterm infants

This study reports the antibiotic susceptibility and genetic resistance determinants of 39 Clostridium butyricum strains isolated from the faeces of preterm infants as well as one reference strain. Results showed that all the strains were susceptible to cefoxitin, imipenem, vancomycin, tigecycline, metronidazole, chloramphenicol and linezolid. Resistance was observed to clindamycin (100%), penicillin G, amoxicillin and piperacillin (15%), tetracycline (7.5%) and erythromycin (5%). Investigation of the genetic basis of the observed resistance phenotypes showed that resistance to penicillin was due to β-lactamase activity and that resistance to tetracycline involved tet(O) or tet(O/32/O) homologue genes. Clindamycin and erythromycin resistance may involve another genetic determinant, different from those commonly described for clostridia.

Clostridial Strain-Specific Characteristics Associated with Necrotizing Enterocolitis

ABSTRACT We aimed at identifying potential bacterial factors linking clostridia with necrotizing enterocolitis (NEC). We compared the phenotypic traits, stress responses, cellular cytotoxicity, and inflammatory capabilities of the largest collection of Clostridium butyricum and Clostridium neonatale strains isolated from fecal samples of NEC preterm neonates (PN) and control PNs. When strain characteristics were used as explanatory variables, a statistical discriminant analysis allowed the separation of NEC and control strains into separate groups. Strains isolated from NEC PN were characterized by a higher viability at 30°C (P = 0.03) and higher aerotolerance (P = 0.01), suggesting that NEC strains may have a competitive and/or survival advantage in the environmental gastrointestinal tract conditions of NEC PN. Heat-treated NEC bacteria induced higher production of interleukin-8 in Caco-2 cells (P = 0.03), suggesting proinflammatory activity. In vitro, bacteria, bacterial components, and fecal filtrates showed variable cytotoxic effects affecting the cellular network and/or cell viability, without specific association with NEC or control samples. Altogether, our data support the existence of a specific clostridial strain signature associated with NEC. IMPORTANCE Clostridia are part of the commensal microbiota in preterm neonates (PN). However, microbiota analyses by culture and metagenomics have linked necrotizing enterocolitis (NEC) and intestinal colonization with clostridial species. Nevertheless, little is known about the specific characteristics that may be shared by clostridia associated with NEC compared to commensal clostridia. Therefore, our goal was to identify specific bacterial factors linking clostridial strains with NEC. We report the existence of a specific bacterial signature associated with NEC and propose that activation of the innate immune response may be a unifying causative mechanism for the development of NEC independent of a specific pathogenic organism. The present study provides new insights into NEC pathophysiology that are needed for better diagnostics and strategies for implementing prevention of the disease.