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Antimicrobial Agents and Chemotherapy, October 2009, p. 4231-4239, Vol. 53, No. 10
0066-4804/09/$08.00+0 doi:10.1128/AAC.00510-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, Maryland 20814,1 Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel2
Received 17 April 2009/ Returned for modification 12 June 2009/ Accepted 14 July 2009
The gastric pathogen Helicobacter pylori has developed resistance to virtually all current antibiotics; thus, there is a pressing need to develop new anti-H. pylori therapies. The goal of this work was to evaluate the antibacterial effect of oligo-acyl-lysyl (OAK) antimicrobial peptidomimetics to determine if they might represent alternatives to conventional antibiotic treatment of H. pylori infection. A total of five OAK sequences were screened for growth-inhibitory and/or bactericidal effects against H. pylori strain G27; four of these sequences had growth-inhibitory and bactericidal effects. The peptide with the highest efficacy against strain G27, C12K-2β12, was selected for further characterization against five additional H. pylori strains (26695, J99, 7.13, SS1, and HPAG1). C12K-2β12 displayed MIC and minimum bactericidal concentration (MBC) ranges of 6.5 to 26 µM and 14.5 to 90 µM, respectively, across the six strains after 24 h of exposure. G27 was the most sensitive H. pylori strain (MIC = 6.5 to 7 µM; MBC = 15 to 20 µM), whereas 26695 was the least susceptible strain (MIC = 25 to 26 µM; MBC = 70 to 90 µM). H. pylori was completely killed after 6 to 8 h of incubation in liquid cultures containing two times the MBC of C12K-2β12. The OAK demonstrated strong in vitro stability, since efficacy was maintained after incubation at extreme temperatures (4°C, 37°C, 42°C, 50°C, 55°C, 60°C, and 95°C) and at low pH, although reduced killing kinetics were observed at pH 4.5. Additionally, upon transient exposure to the bacteria, C12K-2β12 showed irreversible and significant antibacterial effects and was also nonhemolytic. Our results show a significant in vitro effect of C12K-2β12 against H. pylori and suggest that OAKs may be a valuable resource for the treatment of H. pylori infection.
Published ahead of print on 20 July 2009.
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