The synthesis of virulence factors and other extracellular proteins responsible for pathogenicity in Staphylococcus aureus is under the control of the agr locus. A secreted agr-encoded peptide, AgrD, processed from the AgrD gene product, is known to be an effector of self-strain activation and cross-strain inhibition of the agr response. Biochemical analysis of AgrD peptides isolated from cultu...

The emergence of serious infections due to community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has fueled interest in the contributions of specific staphylococcal virulence factors to clinical disease. To assess the contributions of agr-dependent factors to the fate of organisms in polymorphonuclear neutrophils (PMN), we examined the consequences for organism and host cel...

Mutations in the staphylococcal virulence regulator gene agr frequently occur during Staphylococcus aureus infection. Whether agr-defective strains are fit for colonization, an important prerequisite for infection, is unknown. Screening by means of assays to detect delta-hemolysin activity and agr autoinducing peptide production indicated that 15 ( approximately 9%) of 160 healthy human subject...

The agr system of Staphylococcus aureus promotes invasion of host tissues, and as expected, agents that block agr quorum sensing have anti-infective properties. Paradoxically, agr-defective mutants are frequently recovered from patients, especially those persistently infected with S. aureus We found that an agr deficiency increased survival of cultured bacteria during severe stress, such as tre...

More than 200 direct CodY target genes in Staphylococcus aureus were identified by genome-wide analysis of in vitro DNA binding. This analysis, which was confirmed for some genes by DNase I footprinting assays, revealed that CodY is a direct regulator of numerous transcription units associated with amino acid biosynthesis, transport of macromolecules, and virulence. The virulence genes regulate...

OBJECTIVE Impaired immunonutritional status has disadvantageous effects on outcomes for cancer patients. Preoperative albumin-to-globulin ratio (AGR) and the prognostic nutrition index (PNI) have been used as prognostic factors in various cancers. We aimed to evaluate the clinical significance of the AGR and PNI in glioblastoma. MATERIALS AND METHODS This retrospective analysis involved 166 p...

Objective(s): Infections by Staphylococcus aureus remain an important health problem. The aims were to detect mecA, staphylococcal cassette chromosome mec (SCCmec), accessory gene regulator (agr), and integrons in S. aureus and to investigate the relationship of agr types with antibiotic resistance of isolates.  Materials and Methods: In this cross-sectional study, 70 S. aureus isolates w...

Staphylococcus aureus infections are a significant cause of morbidity and mortality in health care settings. S. aureus clinical isolates vary in the function of the accessory gene regulator (agr), which governs the expression of virulence determinants, including surface and exoproteins, while agr activity has been correlated with patient outcome and treatment efficiency. Here we describe a dupl...

Staphylococcus aureus secretes a phosphatidylinositol (PI)-specific phospholipase C (PI-PLC) which is able to hydrolyze the membrane lipid PI and membrane protein anchors containing glycosyl-PI. The gene for PI-PLC (plc) was cloned from S. aureus into Escherichia coli. Oligonucleotide probes based on partial protein sequence and polyclonal antibodies raised against the purified protein were use...

A Staphylococcus aureus gene originally identified by signature-tagged mutagenesis as being required for virulence was cloned, sequenced and named svrA. Hydropathy profiles revealed that SvrA is likely to be membrane associated, having two regions with six membrane-spanning domains, the regions separated by an extended hydrophilic loop. When compared with the wild-type strain, an svrA mutant ex...