Agr is an autoinducing, quorum-sensing system that functions in many Gram-positive species and is best characterized in the pathogen Staphylococcus aureus, in which it is a global regulator of virulence gene expression. Allelic variations in the agr genes have resulted in the emergence of four quorum-sensing specificity groups in S. aureus, which correlate with different strain pathotypes. The ...

Humans and animals often become coinfected with pathogen strains that differ in virulence. The ensuing interaction between these strains can, in theory, be a major determinant of the direction of selection on virulence genes in pathogen populations. Many mathematical analyses of this assume that virulent pathogen lineages have a competitive advantage within coinfected hosts and thus predict tha...

Baker, Phillip J. (University of Wisconsin, Madison), and J. B. Wilson. Chemical composition and biological properties of the endotoxin of Brucella abortus. J. Bacteriol. 90:895-902. 1965.-The ability of endotoxin to induce hypoferremia in mice was used to measure the specific activity of various endotoxin preparations of Escherichia coli and Brucella abortus and to determine the endotoxin cont...

BACKGROUND AND PURPOSE Measurement of the main Proteus mirabilis virulence factors would increase our understanding of how the organism infects and colonizes the urinary tract. The purpose of this study was to quantify the virulence factors of twelve P. mirabilis laboratory strains and to determine whether expression of virulence factors of P. mirabilis depends on the presence of homoserine-lac...

Pseudomonas aeruginosa is an opportunistic pathogen causing a variety of life-threatening diseases such as cystic fibrosis and nosocomial infections in burn victims. The ability of P. aeruginosa to cause infection is attributed to the production of virulence factors such as pyocyanin and elastases. These virulence factors are under the control of quorum sensing (QS) a cell to cell communication...

INTRODUCTION AND OBJECTIVE The bacterial strains that cause symptomatic urinary tract infections possess diverse distinctive properties that enable them to overcome the local host defenses. In Escherichia coli, virulence results from the cumulative impact of several virulence factors, which can vary according to the patient populations. Hence, a study was undertaken to assess the prevalence of ...

The ubiquitous "jack-of-all-trades," Aeromonas hydrophila, is a freshwater, Gram-negative bacterial pathogen under revision in regard to its phylogenetic and functional affiliation with other aeromonads. While virulence factors are expectedly diverse across A. hydrophila strains and closely related species, our mechanistic knowledge of the vast majority of these factors is based on the molecula...

Avian pathogenic Escherichia coli (APEC) are responsible for wide ranges of extra-intestinal diseases in poultry including colibacillosis, cellulitis, coligranuloma and yolk sac infection. Numbers of virulence are considered important in the pathogenicity of these diseases. The aims of the present study were phylogenetic typing and virulence genes detection in Escherichia coli </em...