Search results for "Virulence"

Vibrio vulnificus serovar A: an emerging pathogen in European anguilliculture.

2006

The spread of the emerging pathogen Vibrio vulnificus biotype 2 serovar A in Danish anguilliculture is reported. Serovar A was originally isolated in a Spanish eel farm in 2000 and occurred in Denmark in the summer of 2004, affecting eels of 5-10 g body weight cultured in fresh water. The Danish eels showed clinical signs different from those reported for Spanish eels, such as severe haemorrhages in the head and gill region with necrosis of the soft tissues. Danish isolates were biochemically and serologically identical to Spanish serovar A strains and also highly virulent for eels by both intraperitoneal injection and immersion challenges. Vaccination with Vulnivaccine, a vaccine against V…

Staphylococcus aureus résistant à la méthicilline chez des mères et des enfants hospitalisés à Alger : prédominance du clone virulent européen

2014

NON DISPONIBILE

High affinity iron-uptake systems in Vibrio damsela: role in the acquisition of iron from transferrin

1997

In this work, the high affinity iron-acquisition systems displayed by virulent and avirulent strains of Vibrio damsela have been investigated. This species is an autochthonous member of marine ecosystems that can behave as an opportunistic pathogen for fish and mammals. All strains tested (i) were able to grow under the restricted conditions imposed by the iron chelators transferrin (Tf) and EDDHA, (ii) secreted siderophores of hydroxamic type, other than aerobactin and desferal, that were able to stimulate the growth of the auxotroph mutant Arthrobacter flavescens JG9, and (iii) expressed common iron-regulated outer membrane proteins (IROMPs). No change in LPS patterns was observed in resp…

Siderophore-mediated iron acquisition mechanisms in Vibrio vulnificus biotype 2

1996

Vibrio vulnificus biotype 2 is a primary pathogen for eels and, as has recently been suggested, an opportunistic pathogen for humans. In this study we have investigated the ability of V. vulnificus biotype 2 to obtain iron by siderophore-mediated mechanisms and evaluated the importance of free iron in vibriosis. The virulence degree for eels was dependent on iron availability from host fluids, as was revealed by a reduction in the 50% lethal dose for iron-overloaded eels. This biotype produced both phenolate- and hydroxamate-type siderophores of an unknown nature and two new outer membrane proteins of around 84 and 72 kDa in response to iron starvation. No alterations in lipopolysaccharide …

F17-like fimbriae from an invasive Escherichia coli strain producing cytotoxic necrotizing factor type 2 toxin

1994

The F17b fimbriae encoded by the transmissible virulence plasmid Vir, also coding for cytotoxic necrotizing factor type 2, were characterized. A 5.7-kb region of Vir mediates in vitro N-acetylglucosamine-sensitive adhesion to calf intestinal villi. Sequence analysis revealed that this region codes for a structural subunit and an adhesin closely related to the F17-A and F17-G proteins encoded by the F17 fimbrial gene cluster. The F17b-A gene presents an open reading frame of 540 bp encoding a polypeptide of 180 amino acids with a putative signal peptide of 21 residues. The mature protein shows an identity of 74% with the F17-A structural subunit. This 20-kDa protein is recognized by antiseru…

Pathogenicity of intrathoracically administrated Bacillus thuringiensis spores in Blatta orientalis.

2006

Abstract The ability of Bacillus thuringiensis to produce septicaemia in Periplaneta americana and Blatta orientalis has been investigated. Spores and crystals from several wild-type strains as well as spores of a B. thuringiensis crystal-deficient mutant, were first orally administrated at high doses, and no significant mortality was recorded. Intrathoracic injection of spore suspensions in P. americana revealed that this species is not very susceptible to B. thuringiensis spores. B. orientalis , by contrast, was found to be very susceptible to B. thuringiensis , with a LD 50 of about 35,000 spores, that is similar to that reported on Lepidoptera challenged with parenterally injected B. th…

Curcumin derivatives as inhibitors of Gram positive and Gram negative biofilm formation

2015

Discovery and structure-activity relationship studies of irreversible benzisothiazolinone-based inhibitors against Staphylococcus aureus sortase A tr…

2014

Gram-positive bacteria, in general, and staphylococci, in particular, are the widespread cause of nosocomial and community-acquired infections. The rapid evolvement of strains resistant to antibiotics currently in use is a serious challenge. Novel antimicrobial compounds have to be developed to fight these resistant bacteria, and sortase A, a bacterial cell wall enzyme, is a promising target for novel therapies. As a transpeptidase that covalently attaches various virulence factors to the cell surface, this enzyme plays a crucial role in the ability of bacteria to invade the host's tissues and to escape the immune response. In this study we have screened a small molecule library against rec…

Elimination of a bacterial pore-forming toxin by sequential endocytosis and exocytosis

2008

Staphylococcus aureus alpha-toxin is the archetype of bacterial pore forming toxins and a key virulence factor secreted by the majority of clinical isolates of S. aureus. Toxin monomers bind to target cells and oligomerize to form small beta-barrel pores in the plasma membrane. Many nucleated cells are able to repair a limited number of lesions by unknown, calcium-independent mechanisms. Here we show that cells can internalize alpha-toxin, that uptake is essential for cellular survival, and that pore-complexes are not proteolytically degraded, but returned to the extracellular milieu in the context of exosome-like structures, which we term toxosomes.

Staphylococcus aureus virulences faktoru un antibakteriālās rezistences noteikšana

2019

Staphylococcus aureus ir viena no izplatītākajām patogēnajām, gram pozitīvajām baktērijām, kas pateicoties tās virulences faktoriem, tādiem kā toksīniem, enzīmiem un struktūras komponentiem, spēj novājināt organisma imūno atbildi. Tādā veidā veicinot dažādu veselības traucējumu, it īpaši hospitālo infekciju un slimību attīstību. Mūsdienās, lielākoties visā pasaulē, it īpaši Dienvideiropā ir vērojama krasa MRSA izplatības palielināšanās, kas tiek nodrošināta pateicoties S. aureus sastāvā esošajam SCC mec u.c. ģenētiskajiem elementiem. Tādējādi panākot plaša spektra β-laktāma u.c. antibiotiku rezistences veidošanos, kas ar laiku var samazināt medikamentozās terapijas efektivitāti. Darba mērķi…