Peptidoglycan structure of Enterococcus faecium expressing vancomycin resistance of the VanB type

摘要: Resistance to glycopeptide antibiotics in enterococci is due the synthesis of UDP-MurNAc-tetrapeptide-D-lactate (where Mur muramic acid) replacing normal UDP-MurNAc-pentapeptide precursor. The peptidoglycan structures an inducible VanB-type glycopeptide-resistant Enterococcus faecium, D366, and its constitutively resistant derivative, MT9, were determined. Using HPLC, 17 muropeptides identified present regardless whether resistance was expressed or not. 15 determined using MS amino acid analysis. cross-bridge between D-alanine L-lysine consisted one asparagine. No monomer pentapeptide tetrapeptide-D-lactate could be identified. These results obtained with D366 (non-induced) MT9 indicate that, absence vancomycin, cell wall synthetic machinery E. faecium can process lactate-containing precursor as efficiently pentapeptide. In contrast, presence subinhibitory inducing concentrations vancomycin interfered oligomers.