deciphering-imaging-pathogenesis-cording-mycobacterium-abscessus

Deciphering and Imaging Pathogenesis and Cording of <em>Mycobacterium abscessus</em> in Zebrafish Embryos

Zebrafish (Danio rerio) embryos are increasingly used as an infection model to study the function of the vertebrate innate immune system in host-pathogen ...

Université Montpellier

Repeated disinfection of a nebulizer may modify its performance. During 60 cycles of disinfection with the Nuk steam sterilizer (120 nebulizations), the median volume diameter of tobramycin or colistin, nebulization time and various parameters correlated with the membrane weight of the e-Flow rapid are not modified. Results are similar when tap or purified water is used for washing and disinfection.

Does repeated disinfection of the e-Flow rapid nebulizer affect in vitro performance?

[Place for implantable catheters, results of an audit of knowledge of private homecare nurses].

The use of elastomeric diffusers (EDs) has grown together with the expansion of home care. In these devices, the fill volume of the drug reservoir and the flow rate are preset and cannot be modified. The elastomer, which makes up the reservoir walls, is what makes the infusate flow due to the pressure it exerts. The purpose of this work was to quantify, under standardized experimental conditions and following recommended conditions of use, the mechanical performances of the 2 commonly used elastomers (silicone and polyisoprene) and their impact on infusion flow rate consistency. Results show that they exhibit different mechanical performances which leads to concerns regarding the use of these devices for some intravenous (IV) therapies.

Mechanical performances of elastomers used in diffusers.

Membrane peptides appear as an emerging class of regulatory molecules in bacteria, which can interact with membrane proteins, including transporters and sensor kinases. The KdpF peptide, which is cotranscribed with kdpABC genes and regulated by the KdpDE two-component system, is supposed to stabilize the KdpABC potassium transporter complex but may also exhibit unsuspected regulatory function(s). The mycobacterial KdpF can interact with the KdpD histidine kinase, and kdpF overexpression has been shown to reduce intramacrophage replication of Mycobacterium bovis BCG. In this study, we investigated whether KdpF displays similar behavior in another intracellular pathogen, Salmonella enterica serovar Typhimurium. We show that Salmonella KdpF can interact with KdpD in a bacterial two-hybrid assay. We have constructed a Salmonella strain overexpressing kdpF, and we have investigated expression of the kdp regulon, as well as intramacrophage survival. We show that kdpF overexpression reduces expression of kdpA and kdpD genes under potassium limitation. Moreover, kdpF overexpression increases intramacrophage multiplication of S. Typhimurium. Hence, our results indicate that KdpF can play a regulatory role in S. Typhimurium, modulating kdp gene expression and intramacrophage survival, but in a way that differs from the one reported for M. bovis BCG.

Overexpression of the Salmonella KdpF membrane peptide modulates expression of kdp genes and intramacrophage growth.

Peripherally inserted central catheters (PICCs) are increasingly used in patients with cystic fibrosis (CF) or with non-CF bronchiectasis, but little data exist on catheter-related complications in this setting.

Complications of peripherally inserted central catheters in adults with cystic fibrosis or bronchiectasis.

The behaviour of the sporulating soil-dwelling Bacillus cereus sensu lato (B. cereus sl) which includes foodborne pathogenic strains has been extensively studied in relation to its various animal hosts. The aim of this environmental study was to investigate the water compartments (rain and soil water, as well as groundwater) closely linked to the primary B. cereus sl reservoir, for which available data are limited. B. cereus sl was present, primarily as spores, in all of the tested compartments of an agricultural site, including water from rain to groundwater through soil. During rain events, leachates collected after transfer through the soil eventually reached the groundwater and were loaded with B. cereus sl. In groundwater samples, newly introduced spores of a B. cereus model strain were able to germinate, and vegetative cells arising from this event were detected for up to 50 days. This first B. cereus sl investigation in the various types of interrelated environments suggests that the consideration of the aquatic compartment linked to soil and to climatic events should provide a better understanding of B. cereus sl ecology and thus be relevant for a more accurate risk assessment of food poisoning caused by B. cereus sl pathogenic strains.

Christian Dupont

Université Montpellier

Deciphering and Imaging Pathogenesis and Cording of Mycobacterium abscessus in Zebrafish Embryos