Designed Antimicrobial Peptides for Topical Treatment of Antibiotic Resistant Acne Vulgaris

February 3, 2020

SAN FRANCISCO, CA. – Riptide Bioscience, Inc., announces that key results from the application of its antimicrobial drug candidates for inflammatory acne vulgaris infections have been published in the journal Antibiotics, in an article titled “Designed Antimicrobial Peptides for Topical Treatment of Antibiotic Resistant Acne Vulgaris.”

Acne vulgaris, caused by the Gram-positive bacterium Cutibacterium acnes, is a prevalent dermatologic condition with causes considerable cutaneous and psychological morbidity, affecting over 80% of all adolescents and young adults worldwide. Mild forms can be treated with topical antibiotics, with severe forms of inflammatory acne requiring the prolonged use of oral antibiotics resulting in the development of antimicrobial resistance. Current acne treatments present side effects such as erythema, scaling, burning, hair bleaching, bacterial resistance, and birth defects. Widespread application of small-molecule antibiotic treatments such as clindamycin has led to the evolution of resistant strains, such that many countries report that over 50% of strains are already resistant to antibiotics. So widespread is the problem that American Academy of Dermatology guidelines now recommend against monotherapy with currently approved antibiotics, to avert the further proliferation of resistant strains.

Riptide scientists have developed innovative topical treatment alternatives which, once clinically translated, can potentially provide complete microbicidal eradication with minimal safety issues and limited susceptibility to microbial resistance. “For several years we have been engaged in a systematic program to develop antimicrobial peptides which can be administered topically,” reported Riptide’s Chief Scientific Officer, Dr. Jesse Jaynes. These are rationally engineered analogs of naturally occurring peptides that provide the first line of defense against invading pathogens in all multicellular organisms.”

Study co-author Dr. L. Edward Clemens continued, “These peptides show greatly improved efficacy compared with presently used acne treatments. Just as important, they kill acne pathogens upon contact by disrupting the cell membrane, giving the bacteria no opportunity to mutate so as to evolve resistant strains. That’s different from current treatments. The current antibiotics generally are non-lethal. Instead they attempt to interfere with reproduction over many hours, and do so only through biochemical pathways which the bacteria can evolve to circumvent.”

Riptide’s leading designed antimicrobial peptides demonstrated potent broad-spectrum activity against antibiotic resistant strains of C. acnes. They were active against clindamycin resistant isolates, active against tetracycline resistant isolates, and active against erythromycin resistant isolates. The peptides are bactericidal and selectively kill the causative C. acnes microorganisms via an immediate and direct pathogen membrane-lytic mechanism, while leaving mammalian cells unharmed. This unique mechanism has a reduced likelihood of developing bacterial resistance.

The lead peptide, RP556, was evaluated further in a multidrug-resistant C. acnes intradermal murine infection model: the peptide eliminated C. acnes infection following topical application, with no adverse treatment related effects observed. Dr. Clemens concluded, “The results with RP556 are very encouraging. If these results are clinically translated, designed antimicrobial peptides may serve as an important therapy for the topical treatment of recalcitrant acne infections.”

The open access paper entitled: “Designed Antimicrobial Peptides for Topical Treatment of Antibiotic Resistant Acne Vulgaris” 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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