Topical Antimicrobial Treatment Effective in Bacterial Keratitis Model
A recent study showed that Polymer 7 (isopeptide) is a biocompatible topical antibiotic treatment in a rabbit model of bacterial keratitis. Findings from the study were presented by Dr Rajamani Lakshminarayanan at the 15th International Congress on Vision Science and Ophthalmology/Eye in London on August 10, 2017.
The evolution of antimicrobial resistance to antibiotic treatments has increased over time. This has resulted in a need for antiseptics with a high biocompatibility index for the management of topical infections. Agents that target cytoplasmic membranes of prokaryotes are attractive alternatives for combatting microbial resistance, since the fitness cost of modifying microbial membranes is higher.
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In their study, Dr Lakshminarayanan and colleagues tested the antimicrobial activity and mammalian cell cytotoxicity of various cationic polymers, including Polymer 1 (ethylenimine) and Polymer 7, in a rabbit model. According to Dr Lakshminarayanan, both Polymer 1 and Polymer 7 demonstrated good selectivity for microbial cell membranes over microbial cell membranes, and each abrogated the adverse effects of bacteria or bacterial secretomes on cell morphology and cell mitigation.
Polymer 7 in particular demonstrated broad-spectrum antimicrobial properties against carbapenem-resistant enterobacteriocae, vancomycin-resistant enterococcus, methicillin-resistant Staphylococcus aureus (MRSA), multi-drug resistant Pseudomonas aeruginosa, and filamentous fungal pathogens, said Dr Lakshminarayanan. It also showed rapid bactericidal activity, antibiofilm properties, and the ability to inhibit fungal hyphae.
Ultimately, the study indicated that topical instillation of the polymer restored the re-epithelialization in the rabbit corneal scratch wound model and suggested good biocompatibility.
“In a rabbit model of bacterial keratitis, topical instillation of Polymer 7 decreased the bacterial bioburden, corneal edema, and conjunctival redness when compared to topical antibiotics,” Dr Lakshminarayanan concluded. “Together, these results establish excellent safety and efficacy of the polymer for treating topical infections.”
—Christina Vogt
Reference:
Lakshminarayanan R. Membrane selective cationic polymers as biocides for treating topical infections. Paper presented at: 15th International Congress of Vision Science and Ophthalmology/Eye; August 10-11, 2017. London, UK. http://visionscience.conferenceseries.com/abstract/2017/membrane-selective-cationic-polymers-as-biocides-for-treating-topical-infections.