Propionibacterium Acnes and MRSA Specific Bacteriophages as Novel Topical Therapeutics for Antibiotic Resistant Skin Pathogens

Background: Antibiotics are commonly used to treat infections caused by Propionibacterium acnes and Staphylococcus aureus in particular MRSA. Due to the recent reports of emergence of antibiotic resistant strains, novel non-antibiotic treatment modalities such as bacteriophage therapies may prove to be an effective treatment modality.

Purpose: The aim of this study was to isolate specific bacteriophages and determine their efficacy against P. acne and Staphylococcus aureus strains including antibiotic resistant isolates.

Methods: In this study, two primary methods were used to isolate bacteriophages, polyethylene glycol precipitation as well as membrane filtration. Bacteriophages were identified by using plaque assay technique. Bacteriophages were purified by isolating single plagues formed during the plague assay. The titer of each phage isolate was determined by top agar overlay technique and amplified using a host strain to achieve a final concentration of 1.0 x 109 PFU. After the phage stock isolates were purified and amplified, the bacteriophage isolates were tested against various strains. The efficacy of each bacteriophage isolate was analyzed using the SynergyHTXTM multi-mode 96-well plate reader. Bacteriophages with a high Minimum Inhibitory Concentration (MIC) were selected for further testing.

Results: With the high incidence of infections caused by multi-drug resistant pathogens, development of novel and effective non-antibiotic-based therapies such as the one proposed here is of critical importance. We have launched an initiative for establishing a library of various bacteriophages for development of novel and effective phage therapies. Efforts are underway in our laboratory to develop novel topical formulation against antibiotic resistant skin pathogens.