BACKGROUND Vancomycin (glycopeptide)-resistant enterococci (VRE or GRE) can cause serious problems for hospitalized patients due to the limited options for treatment of VRE infections. As infection with VRE increases in hospitals, further knowledge about vancomycin resistant genes is needed. METHODS Isolates of Enterococcus spp. were collected from hospitalized patients in Tehran (Iran) durin...

We report an outbreak of vancomycin-variable vanA(+) enterococci (VVE) able to escape phenotypic detection by current guidelines and demonstrate the molecular mechanisms for in vivo switching into vancomycin resistance and horizontal spread of the vanA cluster. Forty-eight vanA(+) Enterococcus faecium isolates and one Enterococcus faecalis isolate were analyzed for clonality with pulsed-field g...

Background: Vancomycin (glycopeptide)-resistant enterococci (VRE or GRE) can cause serious problems for hospitalized patients due to the limited options for treatment of VRE infections. As infection with VRE increases in hospitals, further knowledge about vancomycin resistant genes is needed. Methods: Isolates of Enterococcus spp. were collected from hospitalized patients in Tehran (Iran) durin...

background: vancomycin (glycopeptide)-resistant enterococci (vre or gre) can cause serious problems for hospitalized patients due to the limited options for treatment of vre infections. as infection with vre increases in hospitals, further knowledge about vancomycin resistant genes is needed. methods: isolates of enterococcus spp. were collected from hospitalized patients in tehran (iran) durin...

The prevailing resistance mechanism against glycopeptides in Gram-positive pathogens involves reprogramming the biosynthesis of peptidoglycan precursors, resulting in d-alanyl-d-lactate depsipeptide termini. Amycolatopsis balhimycina produces the vancomycin-like glycopeptide balhimycin and therefore has to protect itself from the action of the glycopeptide. We studied the roles of the accessory...

In enterococci and in Streptomyces coelicolor, a glycopeptide nonproducer, the glycopeptide resistance genes vanHAX are colocalized with vanRS. The two-component system (TCS) VanRS activates vanHAX transcription upon sensing the presence of glycopeptides. Amycolatopsis balhimycina, the producer of the vancomycin-like glycopeptide balhimycin, also possesses vanHAXAb genes. The genes for the VanR...

Vancomycin is the front-line therapy for treating problematic infections caused by methicillin-resistant Staphylococcus aureus (MRSA), and the spread of vancomycin resistance is an acute problem. Vancomycin blocks cross-linking between peptidoglycan intermediates by binding to the D-Ala-D-Ala termini of bacterial cell wall precursors, which are the substrate of transglycosylase/transpeptidase. ...

In glycopeptide-resistant enterococci and staphylococci, high-level resistance is achieved by replacing the C-terminal d-alanyl-d-alanine of lipid II with d-alanyl-d-lactate, thus reducing glycopeptide affinity for cell wall targets. Reorganization of the cell wall in these organisms is directed by the vanHAX gene cluster. Similar self-resistance mechanisms have been reported for glycopeptide-p...

Avoparcin, a glycopeptide antimicrobial agent related to vancomycin, has been used extensively as a growth promoter in animal feeds for more than 2 decades, and evidence has shown that such use contributed to the development of vancomycin-resistant enterococci. A cluster that includes three genes, vanH, vanA, and vanX, is required for high-level resistance to glycopeptides. In the vancomycin pr...