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Small Molecule Targeting Gram-Positive Bacteria

Licensing Opportunity 

Small Molecule Targeting Gram-Positive Bacteria with Synergistic

Anti-Infective Agent Inhibits Biofilm Growth

 Primary Indication:  methicillin-resistant Staphylococcus aureus (MRSA), s. aureus

Secondary Indication:  gram positive bacteria, biofilms

Novelty and Advantages of PKZ18 Antibiotics

An ideal antibiotic may be one whose efficacy is based not on the inhibition of a single target, but rather on many identical or similar targets with common functions. This is not a “promiscuous drug” because the target sites are chemically and structurally identical or highly similar. Thus, a minimum concentration of this kind of antibiotic would effectively disrupt many gene functions without side effects or off-site effects.

The strategic advantages of the PKZ18 antibiotics are that they target:

  • specific gene transcription regulatory elements exclusively in Gram-positive bacteria in planktonic and biofilm cultures,
  • regulatory elements occurring in nascent mRNAs in the 5’-non-coding sequences,
  • regulatory elements that are chemically and structurally identical or highly similar found in 6-20 genes (depending on the Gram-positive strain) for amino acid metabolism,
  • all Gram-positive bacteria for they exclusively have these regulatory elements; Gram-negative bacteria and the human host do not have any similar RNA chemistry and structure in any RNA.

PKZ18 antibiotics are refractory to resistance and negate emergence of new Gram-positive strains. To mount resistance to the PKZ18 antibiotics, each targeted gene having this regulatory element would require a mutation simultaneous with the other targeted genes.


A single spontaneous mutation occurs at a rate of 10-5 to 10-10 (including in MRSA). Therefore, a Gram-positive pathogen with just five of these genes having identical or similar regulatory elements targeted by PKZ18, would have to have 6-20 simultaneous mutations. The odds of this occurring are approximately 1 in 10-15 in order to emerge resistant to PKZ18.

(There are other possible resistance mechanisms. We reported1 a single poorly growing mutant occurring on a plate of ~1012 MRSA cells in the presence of PKZ18-22, a resistance frequency of 5.6 X 10-12. No mutations occurred in the targeted regulatory elements. There were no changes in either efflux or influx of the antibiotic. The single gene mutation occurred in a gene that regulates mRNA turnover.) 

In contrast to the specific gene transcription regulatory elements targeted by PKZ18, individual riboswitches, RNA elements that control transcription or translation, are specific domains within mRNAs that respond to a metabolite or ion. Each one of the riboswitches is a single element that responds to a single metabolite or an inhibitor. Thus, just a single mutation to the riboswitch would cause resistance to the inhibitor, and result in a resistant strain.

Biofilm formation constitute a major virulence factor in human infections.2 Biofilm-associated infections are a leading cause of morbidity and mortality in hospitalized patients and the prevalence of Gram-positive bacterial, biofilm-associated infections has increased due to the extensive use of medical implant devices. Common antibiotic regiments are not effective against biofilm Gram-positive bacteria because they are naturally protected by a difficult to penetrate, self-produced extracellular polymeric matrix (EPM). PKZ18 has proven to be >7 fold more efficacious than vancomycin in killing MRSA biofilms.2

 Thus, PKZ18 antibiotics are potentially the right choice for the many systemic and biofilm Gram-positive infections, could be the choice for sepsis, and topical applications for wounds.

(Unpublished topical studies on mice show that PKZ18 antibiotics at the level of efficacy cause no visible irritations. No mice showed any life-changes and no systemic irritations or organ changes upon autopsy. Published work demonstrates synergy with commonly-used antibiotics.1 Two patents have been issued by USPTO.)


1 – Small-Molecule Antibiotics Inhibiting tRNA-Regulated Gene Expression Is a Viable Strategy for Targeting Gram-Positive Bacteria

Ville Y. P. Väre, Ryan F. Schneider, Haein Kim, Erica Lasek-Nesselquist, Kathleen A. McDonough and Paul F. Agris Copyright © 2020 Väre et al.

Published in Antimicrobial Agents and Chemotherapy

2 – A New Promising Anti-Infective Agent Inhibits Biofilm Growth by Targeting Simultaneously a Conserved RNA Function That Controls Multiple Genes.

Seyler TM, Moore C, Kim H, Ramachandran S, Agris PF. Antibiotics (Basel). 2021;10(1):41. Published 2021 Jan 4. doi:10.3390/antibiotics10010041

 Intellectual Property:

U.S. Patent # 11,617,741 “Method for Inhibiting Growth of Bacteria”

U.S. Patent # 10,266,527 “T-Box Riboswitch-Binding Anti-Bacterial Compounds”


 Robert Gallo

Director Intellectual Property & Licensing

 Health Research, Inc.

 (1) 518-431-1208