title: The msaABCR operon regulates resistance in vancomycin-intermediate Staphylococcus aureus strains.
abstract: Vancomycin-intermediate Staphylococcus aureus (VISA) strains present an increasingly difficult problem in terms of public health. However, the molecular mechanism for this resistance is not yet understood. In this study, we define the role of the msaABCR operon in vancomycin resistance in three clinical VISA strains, i.e., Mu50, HIP6297, and LIM2. Deletion of the msaABCR operon resulted in significant decreases in the vancomycin MIC (from 6.25 to 1.56 μg/ml) and significant reductions of cell wall thickness in strains Mu50 and HIP6297. Growth of the mutants in medium containing vancomycin at concentrations greater than 2 μg/ml resulted in decreases in the growth rate, compared with the wild-type strains. Mutation of the msaABCR operon also reduced the binding capacity for vancomycin. We conclude that the msaABCR operon contributes to resistance to vancomycin and cell wall synthesis in S. aureus.
authors.affiliation: The University of Southern Mississippi, Hattiesburg, Mississippi, USA.
authors.forename: Dhritiman
authors.initials: D
authors.lastname: Samanta
authors.affiliation: The University of Southern Mississippi, Hattiesburg, Mississippi, USA mohamed.elasri@usm.edu.
authors.forename: Mohamed O
authors.initials: MO
authors.lastname: Elasri
mesh_terms: D000368:Aged; D019881:Aminoacyltransferases / Q000096:biosynthesis; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000096:biosynthesis; D002352:Carrier Proteins / Q000096:biosynthesis; D002473:Cell Wall / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D012808:Sigma Factor / Q000096:biosynthesis; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; C079011:SigB protein, Bacteria; D012808:Sigma Factor; D014640:Vancomycin; D019881:Aminoacyltransferases; C429146:mprF protein, Staphylococcus aureus