Epidermicin NI01 demonstrates potent in vivo activity in a murine model of methicillin-resistant Staphylococcus aureus skin infection

Authors

• Vicky Bennett, Amprologix Ltd.
• Gordon Barker, Amprologix Ltd.
• Andrew Sharp, Evotec, AG
• Victoria L. Birkett, Evotec, AG
• Jennifer Williams, Evotec, AG
• Pani Tourlomousis, Evotec, AG
• Mathew Upton, School of Biomedical Sciences

ORCID

• Mathew Upton: 0000-0003-4287-6396

Document Type

Article

Abstract

Objectives: In the UK, over 16% of antibiotic prescriptions are for skin infections. New approaches are required to treat and prevent such infections, and new therapeutic modalities should be investigated. Epidermicin NI01 is a first-in-class bacteriocin with potent activity and a novel mode of action against MRSA and Streptococci, leading causes of community and healthcare acquired skin infections and a significant burden of antimicrobial resistance (AMR). The activity of NI01 in a model of MRSA skin infection was assessed during this study. Methods: Immunosuppressed male CD1 mice were wounded dorsally using tape-stripping and S. aureus strain USA300 was topically applied. Topical q24 h administration of vehicle (0.5% HMPC) or NI01 (4 dosing regimens in 0.5% HPMC) or 50 mg of Bactroban 2% (mupirocin) or Fucidin 2% (fusidic acid) was initiated at 24 h post-infection (hpi). At 96 hpi, infected skin was recovered for quantitative skin burden analysis. Results: There were no adverse effects observed due to infection or treatment. No reduction in skin burden was seen in the 3% NI01 mono-dose group. Treatments resulted in significant log₁₀ reductions in cfu/g tissue of 2.82 (Fucidin), 2.48 (3% NI01 q24) and 2.47 (Bactroban). The MIC of NI01 for S. aureus strain USA300 was 4 mg/L before the study and ex vivo. Conclusions: These in vivo activity data warrant further development of NI01 for topical therapy of infections caused by drug-resistant priority pathogens. Clinical use could spare conventional antibiotics for serious and systemic infections and would support stewardship efforts to reduce mupirocin resistance in S. aureus.

DOI Link

10.1093/jacamr/dlag115

Publication Date

2026-06-18

Publication Title

JAC-Antimicrobial Resistance

Volume

8

Issue

3

Acceptance Date

2026-06-04

Deposit Date

2026-10-05

Funding

This work was supported in part by an award from UKRI’s Innovate UK Biomedical Catalyst 2023 Round 1 call (Project ID 10071961) and by private investments made to Amprologix.

Additional Links

https://www.scopus.com/pages/publications/105042184694

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Bennett, V., Barker, G., Sharp, A., Birkett, V., Williams, J., Tourlomousis, P., & Upton, M. (2026) 'Epidermicin NI01 demonstrates potent in vivo activity in a murine model of methicillin-resistant Staphylococcus aureus skin infection', JAC-Antimicrobial Resistance, 8(3). Available at: 10.1093/jacamr/dlag115