Comparison of time-to-positivity between two blood culture systems: a detailed analysis down to the genus-level

International audienceA recently developed, automated blood culture system and medium improve the timeto-positivity (TTP) for bacteremia. However, there have thus far been no genus-level analyses using this novel system. We evaluated and compared the changes in blood culture TTP between two systems: BacT/Alert 3D with a blood culture medium containing activated charcoal versus the more recent BacT/Alert Virtuo with a blood culture medium containing polymeric beads. This before-and-after study included blood cultures collected between July 2010 and April 2014 (3D, activated charcoal) and between July 2015 and April 2018 (Virtuo, polymeric beads). A total of 554,732 blood cultures were included, 267,935 (48.30%) during the first period and 286,797 (51.70%) during the second period. Overall, 55,611 (10.02%) tested positive for at least one microorganism. The incubation of the blood culture medium in the Virtuo system was associated with reduced TTP for the most prevalent bacteria, those representing 91.72% (n=51,006) of all the positive blood cultures. The median TTP was reduced by 0.99 hours for Staphylococcus, Enterococcus, Streptococcus, Pseudomonadales, and most of the genera within the order Enterobacterales (except the family Morganellaceae). However, strictly anaerobic bacteria belonging to the genus Bacteroides, representing 0.85% (n=474) of all positive blood cultures, were detected 4.53 hours later using the Virtuo system. Virtuo was associated with a shorter TTP for most bacteria, but this improvement was heterogeneous to the genus level

A Unique Enhancement of Propionibacterium freudenreichii’s Ability to Remove Pb(II) from Aqueous Solution by Tween 80 Treatment

International audienceMicrobial agents have promise for the bioremediation of Pb(II)-polluted environments and wastewater, the biodecontamination of foods, and the alleviation of toxicity in living organisms. The dairy bacterium Propionibacterium freudenreichii is poorly able to remove Pb(II) from aqueous solution at 25 ppm, ranging from 0 to 10% of initial concentration. Here, we report on an original strong enhancement of this activity (ranging from 75% to 93%, p < 0.01) following the addition of a polysorbate detergent (Tween® 80) during or either shortly after the growth of a P. freudenreichii culture. We evaluated the optimal Tween® 80 concentration for pretreatment conditions, documented the role of other detergents, and explored the possible mechanisms involved. Our results reveal a novel, environmentally friendly, low-cost pretreatment procedure for enhancing the selective removal of lead from water by probiotic-documented bacteria.Les agents microbiens sont prometteurs pour la biorestauration des environnements et des eaux usées pollués par le Pb(II), la biodecontamination des aliments et l’atténuation de la toxicité dans les organismes vivants. La bactérie laitière bioremediation; lead removal; Propionibacterium freudenreichii; polysorbate 80; Tween 80est mal en mesure d’éliminer le Pb(II) de la solution aqueuse à 25 ppm, allant de 0 à 10 % de la concentration initiale. Ici, nous faisons état d’une forte augmentation originale de cette activité (allant de 75 % à 93 %, p < 0,01) après l’ajout d’un détergent polysorbate (Tween® 80) pendant ou peu après la croissance d’une culture de P. freudenreichii. Nous avons évalué la concentration optimale de Tween® 80 pour les conditions de prétraitement, documenté le rôle d’autres détergents et exploré les mécanismes possibles. Nos résultats révèlent une nouvelle procédure de prétraitement écologique et peu coûteuse pour améliorer l’élimination sélective du plomb de l’eau par des bactéries documentées par des probiotiques

High carriage of adherent invasive E. coli in wildlife and healthy individuals

Abstract Background Adherent invasive Escherichia coli (AIEC) are suspected to be involved in the pathogenesis of inflammatory bowel diseases. Since AIEC was first described in 1999, despite important progress on its genomic and immune characterizations, some crucial questions remain unanswered, such as whether there exists a natural reservoir, or whether there is asymptomatic carriage. The ECOR collection, including E. coli strains isolated mainly from the gut of healthy humans and animals, constitutes an ideal tool to investigate AIEC prevalence in healthy condition. A total of 61 E. coli strains were examined for characteristics of AIEC. Methods The adhesion, invasion and intramacrophage replication capabilities (AIEC phenotype) of 61 intestinal E. coli strains were determined. The absence of virulence-associated diarrheagenic E. coli pathotypes (EPEC, ETEC, EIEC, EHEC, DAEC, EAEC), and uropathogenic E. coli was checked. Results Out of 61 intestinal strains, 13 (21%) exhibit the AIEC phenotype, 7 are from human origin and 6 are from animal origin. Prevalence of AIEC strains is about 24 and 19% in healthy humans and animals respectively. These strains are highly genetically diverse as they are distributed among the main described phylogroups. Among E. coli strains from the ECOR collection, we also detected strains able to detach I-407 cells. Conclusions Our study described for the first time AIEC strains isolated from the feces of healthy humans and animals

Changes in HLA-B27 Transgenic Rat Fecal Microbiota Following Tofacitinib Treatment and Ileocecal Resection Surgery: Implications for Crohn’s Disease Management

The therapeutic management of Crohn’s disease (CD), a chronic relapsing–remitting inflammatory bowel disease (IBD), is highly challenging. Surgical resection is sometimes a necessary procedure even though it is often associated with postoperative recurrences (PORs). Tofacitinib, an orally active small molecule Janus kinase inhibitor, is an anti-inflammatory drug meant to limit PORs in CD. Whereas bidirectional interactions between the gut microbiota and the relevant IBD drug are crucial, little is known about the impact of tofacitinib on the gut microbiota. The HLA-B27 transgenic rat is a good preclinical model used in IBD research, including for PORs after ileocecal resection (ICR). In the present study, we used shotgun metagenomics to first delineate the baseline composition and determinants of the fecal microbiome of HLA-B27 rats and then to evaluate the distinct impact of either tofacitinib treatment, ileocecal resection or the cumulative effect of both interventions on the gut microbiota in these HLA-B27 rats. The results confirmed that the microbiome of the HLA-B27 rats was fairly different from their wild-type littermates. We demonstrated here that oral treatment with tofacitinib does not affect the gut microbial composition of HLA-B27 rats. Of note, we showed that ICR induced an intense loss of bacterial diversity together with dramatic changes in taxa relative abundances. However, the oral treatment with tofacitinib neither modified the alpha-diversity nor exacerbated significant modifications in bacterial taxa induced by ICR. Collectively, these preclinical data are rather favorable for the use of tofacitinib in combination with ICR to address Crohn’s disease management when considering microbiota

Assessment of Pb(II), Cd(II) and Al(III) Removal Capacity of Bacteria From Food and Gut Ecological Niches: Insights Into Biodiversity to Limit Intestinal Biodisponibility of Toxic Metals

International audienceToxic metals (such as lead, cadmium, and, to a lesser extent, aluminum) are detrimental to health when ingested in food or water or when inhaled. By interacting with heavy metals, gut and food-derived microbes can actively and/or passively modulate (by adsorption and/or sequestration) the bioavailability of these toxins inside the gut. This “intestinal bioremediation” involves the selection of safe microbes specifically able to immobilize metals. We used inductively coupled plasma mass spectrometry to investigate the in vitro ability of 225 bacteria to remove the potentially harmful trace elements lead, cadmium, and aluminum. Interspecies and intraspecies comparisons were performed among the Firmicutes (mostly lactic acid bacteria, including Lactobacillus spp., with some Lactococcus, Pediococcus, and Carnobacterium representatives), Actinobacteria, and Proteobacteria. The removal of a mixture of lead and cadmium was also investigated. Although the objective of the study was not to elucidate the mechanisms of heavy metal removal for each strain and each metal, we nevertheless identified promising candidate bacteria as probiotics for the intestinal bioremediation of Pb(II) and Cd(II)

Adherent-Invasive and Non-Invasive Escherichia coli Isolates Differ in Their Effects on Caenorhabditis elegans’ Lifespan

The adherent-invasive Escherichia coli (AIEC) pathotype has been implicated in the pathogenesis of inflammatory bowel diseases in general and in Crohn’s disease (CD) in particular. AIEC strains are primarily characterized by their ability to adhere to and invade intestinal epithelial cells. However, the genetic and phenotypic features of AIEC isolates vary greatly as a function of the strain’s clonality, host factors, and the gut microenvironment. It is thus essential to identify the determinants of AIEC pathogenicity and understand their role in intestinal epithelial barrier dysfunction and inflammation. We reasoned that soil nematode Caenorhabditis elegans (a simple but powerful model of host-bacterium interactions) could be used to study the virulence of AIEC vs. non- AIEC E. coli strains. Indeed, we found that the colonization of C. elegans (strain N2) by E. coli impacted survival in a strain-specific manner. Moreover, the AIEC strains’ ability to invade cells in vitro was linked to the median lifespan in C. elegans (strain PX627). However, neither the E. coli intrinsic invasiveness (i.e., the fact for an individual strain to be characterized as invasive or not) nor AIEC’s virulence levels (i.e., the intensity of invasion, established in % from the infectious inoculum) in intestinal epithelial cells was correlated with C. elegans’ lifespan in the killing assay. Nevertheless, AIEC longevity of C. elegans might be a relevant model for screening anti-adhesion drugs and anti-invasive probiotics