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Updated: Jul 8, 2026
A Novel Method to Determine the Longitudinal Antibacterial Activity of Drug-Eluting Materials
Published on: March 3, 2023
In vitro activity of omiganan pentahydrochloride tested against vancomycin-tolerant, -intermediate, and -resistant
Thomas R Fritsche1, Paul R Rhomberg, Helio S Sader
1JMI Laboratories, North Liberty, IA 52317, USA. thomas-fritsche@jmilabs.com
Abstract:
Omiganan, a novel topical cationic peptide active against a broad spectrum of bacteria and yeast, is targeted for the prevention of catheter-associated infections. The spectrum of this agent was evaluated against contemporary methicillin-(oxacillin)-resistant Staphylococcus aureus (MRSA; 109 isolates), including subgroups displaying reduced susceptibility to vancomycin. Strain phenotypes included: vancomycin-tolerant (MBC/MIC ratio, > or = 32-fold);vancomycin-intermediate (VISA; MIC values, 4-8 microg/ml); heterogeneous vancomycin-intermediate (hVISA); and vancomycin-resistant (VRSA; MIC values, > or = 16 microg/ml) S. aureus. All S. aureus tested were inhibited by < or = 64 microg/ml of omiganan, with MIC(50)/MIC(90) values of 16/32 microg/ml, respectively. Compared to wild-type S. aureus, MIC(90) values were only 2-fold greater for vancomycin-tolerant, hVISA and VISA strains. The VRSA isolates, representing the most resistant strains tested, were inhibited by 16 microg/ml (mode for all groups). Omiganan demonstrated potent activity against S. aureus, regardless of harbored resistance mechanism. Given the worrisome emergence of S. aureus with reduced susceptibility to vancomycin, the demonstration that omiganan remains equally active against all isolates of this species at a level significantly below the clinical formulation concentration (1% gel; 10,000 microg/ml) is an important attribute.
Insights
Omiganan effectively inhibits all tested strains of Staphylococcus aureus, including those resistant to vancomycin. This broad-spectrum peptide shows potent activity against MRSA, making it a promising agent for preventing catheter-associated infections.
Area of Science:
- Antimicrobial research
- Infectious disease pathology
- Clinical microbiology
Background:
- Catheter-associated infections pose a significant clinical challenge.
- Emergence of antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), necessitates novel therapeutic agents.
- Vancomycin resistance in S. aureus is a growing concern, compromising treatment options.
Purpose of the Study:
- To evaluate the antimicrobial spectrum of omiganan against contemporary MRSA isolates.
- To assess omiganan's activity against MRSA strains with varying degrees of vancomycin susceptibility.
- To determine the potential of omiganan for preventing catheter-associated infections.
Main Methods:
- Antimicrobial susceptibility testing was performed on 109 MRSA isolates.
- Isolates included vancomycin-tolerant, vancomycin-intermediate (VISA), heterogeneous vancomycin-intermediate (hVISA), and vancomycin-resistant (VRSA) strains.
- Minimum Inhibitory Concentration (MIC) and MIC/MBC ratios were determined for omiganan.
Main Results:
- All tested S. aureus isolates were inhibited by omiganan at concentrations ≤ 64 μg/ml (MIC50/MIC90: 16/32 μg/ml).
- Omiganan demonstrated potent activity against vancomycin-tolerant, hVISA, VISA, and VRSA strains, with MIC90 values only 2-fold greater than wild-type strains.
- VRSA isolates were inhibited by 16 μg/ml, indicating consistent efficacy across resistant phenotypes.
Conclusions:
- Omiganan exhibits potent broad-spectrum activity against S. aureus, irrespective of vancomycin resistance mechanisms.
- The consistent efficacy of omiganan against all tested S. aureus isolates, including highly resistant strains, is a significant attribute for its use.
- Omiganan's activity at concentrations well below its clinical formulation suggests its potential as a preventative measure against catheter-associated infections.
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