background: in this study, we investigated the prevalence of staphylococcus aureus agr groups to detect the predominant type according to the source of isolation and assessed the possible relationship between agr groups, types of infection and susceptible or resistance to methicillin. materials and methods: dna of 194 s. aureus isolates were extracted by lysozyme-phenol chloroform method that i...

abstract       background and objective: agr is the most important regulatory system for the expression of staphylococcus aureus virulence factors in different conditions. agr acts as a quorum sensing system in this bacterium which is activated by increased cell concentration during the transition from logarithmic growth phase to stationary phase. its role is to upregulate the secretory virulen...

The production of cell surface proteins in Staphylococcus aureus is generally down-regulated in the postexponential growth phase by the global regulator agr. The effector of this regulation is the RNAIII molecule, which is encoded within the agr locus. RNAIII seems to regulate most target genes at the level of transcription, but it also has an effect on the translation of some genes. To study t...

Background: The aim of this study was to compare the biofilm formation and the prevalence of biofilm-associated genes between the isolates of methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) Staphylococcus aureus. Methods: In total, 209 S. aureus isolates were collected. The antibiotic susceptibility test was conducted using nine antibiotics according to the guidelines of Clinica...

materials and methods this definitive and cross-sectional study was conducted in tehran, iran. a total of 15 s. aureus isolates were collected from wound samples with sterile swabs and were identified by the conventional diagnostic tests. the antibiotic susceptibility pattern was performed according to the clinical and laboratory standards institute (clsi, 2012) protocol. the meca gene, staphyl...

The repressor CodY is reported to inhibit metabolic genes mainly involved in nitrogen metabolism. We analyzed codY mutants from three unrelated Staphylococcus aureus strains (Newman, UAMS-1, and RN1HG). The mutants grew more slowly than their parent strains in a chemically defined medium. However, only codY mutants were able to grow in medium lacking threonine. An excess of isoleucine resulted ...

The expression of many virulence determinants in Staphylococcus aureus including alpha-hemolysin-, protein A-, and fibronectin-binding proteins is controlled by global regulatory loci such as sar and agr. In addition to controlling target gene expression via agr (e.g. alpha-hemolysin), the sar locus can also regulate target gene transcription via agr-independent mechanisms. In particular, we ha...

A significant number of genome sequences of Clostridium botulinum and related species have now been determined. In silico analysis of these data revealed the presence of two distinct agr loci (agr-1 and agr-2) in all group I strains, each encoding putative proteins with similarity to AgrB and AgrD of the well-studied Staphylococcus aureus agr quorum sensing system. In S. aureus, a small diffusi...

The virulence of Staphylococcus aureus is controlled by the accessory gene regulator (agr) system, including an extracellular inducer encoded by agrD. Variable agr PCR restriction fragment length polymorphism (RFLP) patterns of unique S. aureus strains (n = 192) were determined for a region comprising agrD and parts of the neighboring agrC and agrB genes. Twelve unique RFLP patterns were identi...