Faculty Opinions recommendation of Fluorescence ratio imaging microscopy shows decreased access of vancomycin to cell wall synthetic sites in vancomycin-resistant Staphylococcus aureus.

2007 ◽  
Author(s):  
Lynn Silver
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Fluorescence Ratio ◽  
Fluorescence Ratio Imaging ◽  
Ratio Imaging ◽  
Vancomycin Resistant

scholarly journals Fluorescence Ratio Imaging Microscopy Shows Decreased Access of Vancomycin to Cell Wall Synthetic Sites in Vancomycin-Resistant Staphylococcus aureus

2007 ◽  
Vol 51 (10) ◽  
pp. 3627-3633 ◽  
Author(s):  
Pedro M. Pereira ◽  
Sérgio R. Filipe ◽  
Alexander Tomasz ◽  
Mariana G. Pinho
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Binding Capacity ◽  
Live Cells ◽  
Resistant Bacteria ◽  
Fluorescence Ratio ◽  
Lipid Ii ◽  
Fluorescence Ratio Imaging ◽  
Ratio Imaging

ABSTRACT A new method of fluorescence ratio imaging microscopy was used to compare the in vivo binding capacity and the access of a fluorescent derivative of vancomycin to the cell wall synthetic sites in isogenic pairs of vancomycin-susceptible and -resistant laboratory mutants and vancomycin-intermediate and -susceptible clinical isolates of Staphylococcus aureus. Live cells of resistant strains were found to bind approximately 1.5 times more antibiotic, but there was no correlation between the increased binding capacity and the MICs of the strains. In both susceptible and resistant bacteria, the subcellular sites of wall synthesis were localized to the division septa, but the rate of diffusion of drug molecules to these sites was reduced in resistant cells. The findings allow a reinterpretation of the mechanism of vancomycin resistance in which the path of vancomycin to its lethal target (lipid II) is considered to be through the division septum and therefore is dependent on the stage of the staphylococcal cell cycle.

scholarly journals Penicillin-Binding Protein 2 Is Essential for Expression of High-Level Vancomycin Resistance and Cell Wall Synthesis in Vancomycin- Resistant Staphylococcus aureus Carrying the Enterococcal vanA Gene Complex

2004 ◽  
Vol 48 (12) ◽  
pp. 4566-4573 ◽  
Author(s):  
Anatoly Severin ◽  
Shang Wei Wu ◽  
Keiko Tabei ◽  
Alexander Tomasz
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Binding Protein ◽  
Inducible Promoter ◽  
Protein Product ◽  
Vancomycin Resistance ◽  
Penicillin Binding Protein ◽  
Oxacillin Resistance ◽  
Vancomycin Resistant ◽  
High Level

ABSTRACT A combination of biochemical and genetic experiments were performed in order to better understand the mechanism of expression of high-level vancomycin resistance in Staphylococcus aureus. The transcription of pbp2 of the highly vancomycin- and oxacillin-resistant strain COLVA200 and its mutant derivative with inactivated mecA were put under the control of an inducible promoter, and the dependence of oxacillin and vancomycin resistance and cell wall composition on the concentration of the isopropyl-β-d-thiogalactopyranoside inducer was determined. The results indicate that mecA—the genetic determinant of oxacillin resistance—while essential for oxacillin resistance, is not involved with the expression of vancomycin resistance. Penicillin binding protein 2A, the protein product of mecA, appears to be unable to utilize the depsipeptide cell wall precursor produced in the vancomycin-resistant cells for transpeptidation. The key penicillin binding protein essential for vancomycin resistance and for the synthesis of the abnormally structured cell walls characteristic of vancomycin-resistant S. aureus (A. Severin, K. Tabei, F. Tenover, M. Chung, N. Clarke, and A. Tomasz, J. Biol. Chem. 279:3398-3407, 2004) is penicillin binding protein 2.

scholarly journals Clinical Isolate of Vancomycin-HeterointermediateStaphylococcus aureus Susceptible to Methicillin and In Vitro Selection of a Vancomycin-Resistant Derivative

2001 ◽  
Vol 45 (1) ◽  
pp. 349-352 ◽  
Author(s):  
Sophie Bobin-Dubreux ◽  
Marie-Elisabeth Reverdy ◽  
Chantal Nervi ◽  
Martine Rougier ◽  
Anne Bolmström ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Clinical Isolate ◽  
Electron Micrographs ◽  
Parent Strain ◽  
In Vitro Selection ◽  
Glycopeptide Antibiotics ◽  
Vancomycin Resistant ◽  
Selection Of

ABSTRACT A Staphylococcus aureus strain with low-level heteroresistance to vancomycin (designated MER) but susceptible to methicillin was isolated from an outpatient with conjunctivitis who did not receive any glycopeptide antibiotics. Incubation of the parent strain, MER, with increasing concentrations of vancomycin led to rapid selection of a stable progeny homogeneously resistant to vancomycin. Electron micrographs of strain MER showed enhanced cell wall thickness and abnormal septations typically seen with methicillin-resistantS. aureus having intermediate susceptibility to vancomycin.

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