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Oritavancin: Mechanism of Action

2012; Oxford University Press; Volume: 54; Issue: suppl_3 Linguagem: Inglês

10.1093/cid/cir920

1537-6591

George G. Zhanel, Frank Schweizer, James A. Karlowsky,

Bacterial biofilms and quorum sensing

Oritavancin is a semisynthetic lipoglycopeptide analogue of vancomycin that contains the heptapeptide core common to all glycopeptides. It differs from vancomycin by the presence of a hydrophobic N-4-(4-chlorophenyl)benzyl (also referred to as 4'-chlorobiphenylmethyl) substituent on the disaccharide sugar, the addition of a 4-epi-vancosamine monosaccharide to the amino acid residue in ring 6, and the replacement of the vancosamine moiety by 4-epi-vancosamine. One mechanism of action of oritavancin is inhibition of transglycosylation (important in peptidoglycan synthesis) by binding to D-alanyl-D-alanine stem termini in Gram-positive bacteria. The inhibition of peptidoglycan synthesis via inhibition of transglycosylation is common to all glycopeptides (vancomycin) and lipoglycopeptides. Secondary binding of oritavancin to the pentaglycyl (Asp/Asn) bridging segment in peptidoglycan also occurs, which distinguishes it from vancomycin and contributes to oritavancin's activity versus vancomycin-resistant organisms. The presence of the hydrophobic 4'-chlorobiphenylmethyl group allows for interaction and disruption of the cell membrane, resulting in depolarization, permeabilization, and concentration-dependent, rapid cell death. This mechanism is shared with telavancin but not vancomycin and results in activity against daptomycin-nonsusceptible organisms. In conclusion, oritavancin's mechanism of action involves at least 3 known mechanisms: inhibition of transglycosylation, inhibition of transpeptidation, and cell membrane interaction/disruption. Oritavancin's multiple mechanisms of action confer activity against vancomycin-susceptible and -resistant organisms, as well as rapid, concentration-dependent killing versus actively growing, stationary phase, and biofilm-producing Gram-positive bacteria.