Induction signals for vancomycin resistance encoded by the vanA gene cluster in Enterococcus faecium.

The induction of vancomycin resistance in enterococci containing the vanA gene cluster is thought to be controlled by a two-component sensor-response regulator system encoded by vanR and vanS. Eight inducing compounds were identified by screening a panel of more than 6,800 antibiotics and synthetic compounds including the three tested glycopeptides (vancomycin, avoparcin, and ristocetin), two other cell wall biosynthesis inhibitors (moenomycin and bacitracin), two cyclic peptide antibiotics (antibiotic AO341 beta and polymyxin B), and a macrocyclic lactone antibiotic (moxidectin). Induction activity by structurally unrelated antibiotics suggests that the induction signal is not a structural feature of vancomycin.