Search results for "Virulence"

Exploring evolutionary responses to increasing temperature in an environmental opportunistic pathogen

2017

Genetic and environmental factors associated with the virulence of fish pathogen Flavobacterium columnare

2016

The efficacy of two immunostimulants against Flavobacterium columnare infection in juvenile rainbow trout (Oncorhynchus mykiss).

2009

Abstract Bacterium Flavobacterium columnare is the causative agent of columnaris disease in many wild and farmed fish species. Immunostimulants are used with success in aquaculture against many pathogens, but the ability to improve innate resistance to columnaris disease has not been studied. Fingerling rainbow trout were treated with two immunostimulants, yeast β-glucan and β-hydroxy-β-methylbutyrate (HMB). Selected innate immune function parameters, the production of reactive oxygen species (ROS) by whole blood and by isolated head kidney leukocytes, plasma lysozyme activity and complement bacteriolytic activity, were determined to assess the immune status of fish. The fish were then bath…

Staphylococcus epidermidis biofilmu veidošana un rezistences pret meticilīnu noteikšana, lietojot fenotipiskās un molekulāri bioloģiskās izmeklēšanas…

2018

Staphylococcus epidermidis ir veselas cilvēka ādas un gļotādas dabiskās mikrofloras sastāvdaļa, kas ir viens no visbiežāk sastopamajiem cilvēka mikrobioma pārstāvjiem. Epidermālais stafilokoks ir oportūnists, kas saimniekorganismam spēj kolonizēt gan ādu, gan gļotādu. Kaut arī S. epidermidis piemīt mazāk virulences faktoru, nekā radiniekam S. aureus, epidermālais stafilokoks ir kļuvis par vienu no visbiežāk izolētajiem koagulāzes negatīvajiem stafilokokiem intrahospitālajā vidē. Tomēr neskatoties uz to, ka epidermālajam stafilokokam ir mazāk virulences faktoru, tas ir kļuvis par nopietnu un komplicētu problēmjautājumu gan ārstniecības iestādēm, gan sabiedrības veselībai kopumā. Pētījuma mēr…

Pneumococcal HxxHxH triad – Copper(II) interactions – How important is the ‘x’?

2019

Abstract PhtA, a Streptococcus pneumoniae polyhistidine triad protein, which contributes to virulence by interacting with components of the immune system, by being involved in adherence of bacteria and in Zn(II) uptake, contains five copies of the HxxHxH sequence. Since this motif is also present in numerous Cu(II) binding proteins, we decided to focus on the bioinorganic chemistry of copper(II) with three of such PhtA repeats, in order to understand which of the PhtA triads binds Cu(II) with the highest affinity and explain if Cu(II) would be able to outcompete Zn(II) from its native binding site under physiological metal concentrations.

Bacteriophage Resistance Affects Flavobacterium columnare Virulence Partly via Mutations in Genes Related to Gliding Motility and Type IX Secretion S…

2020

AbstractIncreasing problems with antibiotic resistance has directed interest towards phages as tools to treat bacterial infections in the aquaculture industry. However, phage resistance evolves rapidly in bacteria posing a challenge for successful phage therapy. To investigate phage resistance in the fish pathogenic bacterium Flavobacterium columnare, two phage-sensitive, virulent wild-type isolates, FCO-F2 and FCO-F9, were exposed to phages and subsequently analyzed for bacterial viability and colony morphology. Twenty-four phage-exposed isolates were further characterized for phage resistance, antibiotic susceptibility, motility, adhesion and biofilm formation on polystyrene surface, prot…

Wanted : pathogenesis-related marker molecules for Fusarium oxysporum

2003

Summary Although Fusarium oxysporum pathogens cause severe wilts in about 80 botanical species, the mechanisms of pathogenicity and symptom induction are poorly understood. Knowledge about the genetic and biochemical pathways involved in the pathogenesis of F. oxysporum would be invaluable in getting targets for both fungicide development and search for biocontrol agents. In this respect, we described the main approaches that have been developed to identify some mechanisms underlying the pathogenesis of F. oxysporum . During the last decades, the potential functions triggering of F. oysporum pathogenicity have mainly been investigated by comparing soilborne pathogenic strains with nonpathog…

Virulent and nonvirulent Flavobacterium columnare colony morphologies: characterization of chondroitin AC lyase activity and adhesion to polystyrene

2011

Aims:  Colony morphology variants of fish pathogenic Flavobacterium columnare were studied to clarify the role of colony morphology change in the virulence of the bacterium. Typical rhizoid colony (Rz) variants are virulent and moderately adherent, nonrhizoid rough (R) colony variants are nonvirulent and highly adherent, and soft colony (S) variants are nonvirulent and poorly adherent. Methods and Results:  Chondroitin AC lyase activity, adhesion to polystyrene at different temperatures and after modification of bacterial surface, and lipopolysaccharide (LPS) profiles of the variants were studied. The chondroitinase activity was significantly higher in the virulent, rhizoid variants than in…

Biochemical and toxigenic properties of Vibrio furnissii isolated from a European eel farm

1995

Abstract The present study describes for the first time the isolation of Vibrio furnissii strains from a European eel culture system which are pathogenic for eels ( Anguilla anguilla ) (LD 50 dose, 10 6 cfu/fish). Biochemical characterization of the isolates was performed by API 20E system and by classical numerical taxonomy. Growth at 4 °C, and with 6–8% (w/v) NaCl in a broth medium were necessary to differentiate Vibrio furnissii from Aeromonas species when the API 20E system was used. Virulence for eels of V. furnissii isolates was demonstrated by intraperitoneal injection of living cells. The extracellular products (ECPs) produced by V. furnissii were lethal to elvers and induced some o…

Toxicity of the extracellular products ofVibrio damsela isolated from diseased fish

1993

In this work we analyzed the pathogenic in vivo and in vitro activities for both fish and mammals of extracellular products (ECP) of several isolates of Vibrio damsela implicated in disease problems in marine culture. The ECP from all the strains were strongly lethal for fish (LD50 ranging from 0.06 to 3.7 μg protein/g fish) and mice (LD50 ranging from 0.02 to 0.43 μg protein/g mouse), causing death between 4 and 72 h after inoculation. These ECP samples possessed low proteolytic activity without production of caseinase, gelatinase, or elastase. However, most of them showed remarkable phospholipase and hemolytic activity for sheep, human, and turbot red blood cells. In addition, all the ECP…