Cold Atmospheric Plasma-Aerosol Treatment of Equine Antibiotic-Resistant Wound Infection: A Preliminary Case Series

Background: Wound infections are common sequelae of wound treatment in horses. Secondary bacterial colonization with antimicrobial resistant microorganisms is of particular concern and is of crucial importance regarding the “One Health Concept”. Due to frequent antimicrobial resistance (AMR), conventional treatments often involve determining resistance and sensitivity using time-consuming antibiograms. Infections with multi-resistant pathogens are especially challenging. This case series presents studies of four horses evaluating the efficacy of Cold Atmospheric Plasma-Aerosol (CAP-A) as a standalone treatment for equine wound infections. Methods: A sampling unit of horses aged 5 weeks to 11 years presented with various infected wounds which were treated with CAP-A. Treatment was administered once daily for up to two months; each session consisted of 2 × 3 min nebulization cycles. Following 10 days of treatment, methicillin-resistant Staphylococcus aureus (MRSA) was no longer culturally detectable, and advanced wound healing was observed. Microbiological samples were collected before and after the treatment period, and the antibiotic resistance of pathogens was determined. Photographs were used to document wound progression and healing process. Results: Antibiograms and microbiological examinations identified several multi-resistant bacteria in all horses. CAP-A treatment decreased microbial load of pathogenic flora and removed MRSA without the use of antibiotics. Conclusions: CAP-A therapy demonstrated promising results as a non-pharmacological treatment option for equine wound infections with multi-resistant bacteria such as MRSA and multi-resistant Gram-negative bacteria, achieving both clinical and microbiological improvement. Horses tolerated sessions without any signs of discomfort. Further research should be based on a clinical follow-up as part of a prospective study with a larger sample size and negative control to draw definite conclusions about the efficacy of the treatment.