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FASEB J. 2013 Dec;27(12):4834-43. doi: 10.1096/fj.13-237610. Epub 2013 Aug 22.

Simultaneous breakdown of multiple antibiotic resistance mechanisms in S. aureus.

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  • 11Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel. amor@tx.technion.ac.il.

Abstract

In previous studies, the oligo-acyl-lysyl (OAK) C12(ω7)K-β12 added to cultures of gram-positive bacteria exerted a bacteriostatic activity that was associated with membrane depolarization, even at high concentrations. Here, we report that multidrug-resistant Staphylococcus aureus strains, unlike other gram-positive species, have reverted to the sensitive phenotype when exposed to subminimal inhibitory concentrations (sub-MICs) of the OAK, thereby increasing antibiotics potency by up to 3 orders of magnitude. Such chemosensitization was achieved using either cytoplasm or cell-wall targeting antibiotics. Moreover, eventual emergence of resistance to antibiotics was significantly delayed. Using the mouse peritonitis-sepsis model, we show that on single-dose administration of oxacillin and OAK combinations, death induced by a lethal staphylococcal infection was prevented in a synergistic manner, thereby supporting the likelihood for synergism to persist under in vivo conditions. Toward illuminating the molecular basis for these observations, we present data arguing that sub-MIC OAK interactions with the plasma membrane can inhibit proton-dependent signal transduction responsible for expression and export of resistance factors, as demonstrated for β-lactamase and PBP2a. Collectively, the data reveal a potentially useful approach for overcoming antibiotic resistance and for preventing resistance from emerging as readily as when bacteria are exposed to an antibiotic alone.

KEYWORDS:

OAK; host defense peptides; membrane potential; oxacillin; peptidomimetics; synergy

PMID:
23970798
[PubMed - indexed for MEDLINE]
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