An Innovative Topical Peptide for the Empirical Treatment of Civilian and Combat Wound Infections

August 19, 2019

SAN FRANCISCO, CA. – Riptide Bioscience, Inc announces that the results of its research on the development of a novel antimicrobial peptide for the treatment of infected wounds have been published in the journal Frontiers in Microbiology.

The relentless growth of multidrug antimicrobial resistance and generation of recalcitrant biofilm are major obstacles in treating wounds. The U.S. military experience in Iraq and Afghanistan included an epidemic of wound infections featuring multidrug-resistant organisms (MDROs). Ballistic wound infection has become the greatest threat to the life and recovery of the casualty who survives the initial insult. Innovation in anti-infective agents with broad-spectrum fungal and bacterial activity, including MDROs and recalcitrant biofilm, is urgently needed so infections can be reduced to a preventable complication of combat-related injuries.

Acute bacterial skin and skin structure infections (ABSSSI) are responsible for 750,000 hospitalizations per year and are associated with substantial costs. Broad-spectrum coverage for gram-negative pathogens and multidrug-resistant gram-positive bacteria are limited. Frequent outbreaks occur with military recruits and where civilian personnel are confined.

The work, to generate a topical broad-spectrum treatment for wound infections, was supported by the Office of the Assistant Secretary of Defense for Health Affairs through the Defense Medical Research and Development Program under Award No. W81XWH-15-1-0616. RP557 is the product of three design iterations by Riptide co-author and Chief Scientific Officer Dr. Jesse Jaynes. Dr Jaynes commented, “RP557 derives from natural antimicrobial peptides, which are the first lines of defense against bacterial invasion. These are used by most animals and plants, and have likely been key natural defenses for many millions of years. But RP557 is singular in its highly specific activity against pathogens with very low toxicity to normal cells. It’s really something special.”

The paper describes the evaluation of RP557, a 17-amino acid dAMP (designed AntiMicrobial Peptide) that is the product of three iterative cycles of peptide design and synthesis followed by assays for pathogen killing, safety and stability. The research culminated in the generation of RP557, a water-soluble, chemically stable dAMP that exhibits broad-spectrum activity against both Gram-negative and Gram-positive clinical bacterial isolates and biofilm and fungi. And while the utility of dAMPs has in the past been hampered by their toxicity to host tissues, RP557 at concentrations that kill both S. aureus and P. aeruginosa, has no effect on normal cells. The high selectivity index of RP557 for microbes rather than normal tissues indicates that it has strong potential for therapeutic translation.

The ability to treat infected wounds empirically with one drug versus multiple drugs for each specific strain present in the wound is revolutionary and will subsequently diminish the chance for systemic infection. The clinical implementation of RP557 could prove a novel method of dealing with antibiotic resistance while at the same time providing a new broad-spectrum treatment against biofilms, fungi, and drug-resistant bacterial infections.

This open access paper entitled: “Evaluation of the Antimicrobial Peptide RP557, for the Broad Spectrum Treatment of Wound Pathogens and Biofilm” is available at

Riptide Bioscience, Inc., with laboratories in Vallejo, California, maintains an intensive program of research into peptide-based therapeutics. Contact:

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