Introduction: Cutibacterium (C.) acnes obtains a major role in the pathogenesis of acne vulgaris. Over the past 4 decades the prevalence of antibiotic resistant of C. acnesstrains has been on the rise. Of the few alternative treatments under research. Bacteriophages are viruses that specifically lyse bacteria and can be used to eradicate bacterial infections. We hypothesized that phage therapy will prove effective in treating acne lesions in vitro and in mice.
Methods: 36 C. acne Isolates antibiotic&phage susceptibility were assessed. ICR mice were used to induce an acne mice model by intradermal injection of C. acnes, combined with topical application of sebum. Mice were assigned into groups of 17 mice each. One was treated topically for 8 days with a 2.5% Carbapol gel containing anti phages, while placebo mice were treated with vehicle only.
Inflammatory lesions at the site of C. acnes injection were evaluated by a clinical score. We used flow cytometry on skin biopsies from inflammatory lesions, in order to assess the levels of neutrophils in the lesions at different time points.
Results: In vitro 88.8% of C. acnes strains showed some susceptibility to all phages, while 69.4% of strains were antibiotic susceptible. Moreover, of the antibiotic resistant strains, 100% were susceptible to at least one phage. In vivo, mice treated with topical anti C. acnes phages showed no side-effects, had significantly superior clinical scores, compared to placebo group. There was a significant reduction in neutrophils levels in treated mice, without similar change in the placebo group. Placebo and phage treated groups were significantly different.
Conclusions:  Based on our results, we conclude that phage therapy may have a strong potential as a topical treatment of acne moreover, due to the dominance of noutophils in acne pathogenesis, phages ability to inhibit their migration might correlate to clinical improvement.

**Introduction:** _Cutibacterium (C.) acnes_ obtains a major role in the pathogenesis of acne vulgaris. Over the past 4 decades the prevalence of antibiotic resistant of _C. acnes_strains has been on the rise. Of the few alternative treatments under research. Bacteriophages are viruses that specifically lyse bacteria and can be used to eradicate bacterial infections. We hypothesized that phage therapy will prove effective in treating acne lesions _in vitro_ and in mice.
**Methods:** 36 _C. acne Isolates_ antibiotic&phage susceptibility _were_ assessed. ICR mice were used to induce an acne mice model by intradermal injection of _C. acnes_, combined with topical application of sebum. Mice were assigned into groups of 17 mice each. One was treated topically for 8 days with a 2.5% Carbapol gel containing anti phages, while placebo mice were treated with vehicle only.
Inflammatory lesions at the site of _C. acnes_ injection were evaluated by a clinical score. We used flow cytometry on skin biopsies from inflammatory lesions, in order to assess the levels of neutrophils in the lesions at different time points.
**Results:** _In vitro_ 88.8% of _C. acnes_ strains showed some susceptibility to all phages, while 69.4% of strains were antibiotic susceptible. Moreover, of the antibiotic resistant strains, 100% were susceptible to at least one phage. _In vivo_, mice treated with topical anti _C. acnes_ phages showed no side-effects, had significantly superior clinical scores, compared to placebo group. There was a significant reduction in neutrophils levels in treated mice, without similar change in the placebo group. Placebo and phage treated groups were significantly different.
**Conclusions:**  Based on our results, we conclude that phage therapy may have a strong potential as a topical treatment of acne moreover, due to the dominance of noutophils in acne pathogenesis, phages ability to inhibit their migration might correlate to clinical improvement.

In-Vitro and In-Vivo Topical Phage Therapy for the Treatment of Acne in an Acne Mice Model

Exploring the intricacies of host-pathogen communication is vital in order to understand why
some microbes persist within a host, while others are effectively cleared. As such,
host-pathogen communication is an urgent area of research underpinning human health
and disease, especially given the emerging concerns of antibiotic resistance.
Understanding host-pathogen pathways requires intricate knowledge in the fields of both
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