OBJECTIVES Multidrug efflux is a resistance mechanism that simultaneously affects susceptibility to many structurally unrelated compounds. The regulation of norA expression, which encodes the Staphylococcus aureus NorA multidrug efflux pump, is not well understood but the MgrA global regulator and the arlRS locus are involved. The expression of genes encoding proteins related to NorA, such as Q...

The prognostic significance of AgNOR proteins in stage II-III rectal cancers treated with chemoradiotherapy was evaluated. Silver staining was applied to the 3μm sections of parafin blocked tissues from 30 rectal cancer patients who received 5-FU based chemoradiotherapy from May 2003 to June 2006. The microscopic displays of the cells were transferred into the computer via a video camera. AgNOR...

Emerging drug resistance in clinical isolates of Staphylococcus aureus might be implicated to the overexpression of NorA efflux pump which is capable of extruding numerous structurally diverse compounds. However, NorA efflux pump is considered as a potential drug target for the development of efflux pump inhibitors. In the present study, NorA model was constructed based on the crystal structure...

staphylococcus aureus causes a wide variety of infections worldwide. methicillin-resistant s. aureus is one of most common causes of nosocomial and community acquired infections. the fluoroquinolones are an important class of antibiotics that used to treat infections caused by s. aureus. today, a significant increase in the rate of ciprofloxacin resistance in methicillin-resistant s. aureus str...

To dissect genetically the regulation of NorA, a multidrug transporter of Staphylococcus aureus, we analyzed the differential expression of the norA promoter using a transcriptional fusion with a beta-lactamase reporter gene. Expression studies with an arlS mutant revealed that the norA promoter is ArlS dependent. The arlR-arlS locus was shown to code for a two-component regulatory system. The ...

The NorA efflux pump considered as one of the contributors to antibiotic resistance in Staphylococcus aureus strains. One of the challenges of the researchers is finding natural plant compounds with the ability to inhibit the pumps. The aim of this study was to investigate the inhibitory effect of thyme (Thymus vulgaris) extract on NorA efflux pump in ciprofloxacin-resistant strains of S. aureu...

MgrA is a global regulator in Staphylococcus aureus. Differences in the effects of MgrA on norA expression have been reported for different strains, which varied in rsbU, a gene that affects the expression of sigB, which encodes an alternative sigma factor involved in stress responses. We hypothesized that MgrA was modified by sigB-dependent factors that affected its ability to control the expr...

The multidrug transporter NorA contributes to the resistance of Staphylococcus aureus to fluoroquinolone antibiotics by promoting their active extrusion from the cell. Previous studies with the alkaloid reserpine, the first identified inhibitor of NorA, indicate that the combination of a chemical NorA inhibitor with a fluoroquinolone could improve the efficacy of this class of antibiotics. Sinc...