# Anti-Bacterial Action of Plasma Multi-Jets in the Context of Chronic Wound Healing
## 1 Introduction
Bacterial endospores including _Clostridium difficile_ and vegetative bacteria including _Enterococcus ficeum_ were considered. It was concluded that air plasma can disinfect dry inanimate surfaces contaminated with bacteria, including bacterial endospores. The effect was mainly limited by the bacterial density. The perspective demonstrated that plasma could serve as an alternative in the disinfection of medical instruments complementary to the standard cleaning procedures. [PERSON] et al. [36] reported on the sensitivity of two drug-resistant bacteria to low-temperature air plasma in catheter-associated urinary tract infections. Low temperature air plasma demonstrated efficiency to decontaminate resistant _E. coli_ and _Enterococci_ through the destruction of the ribosome and other organelles inside the bacteria. Besides all of these plasma and plasma afterglow treatments, two other protocols can be envisioned for decontamination applications. They consist of plasma treated solution delivery or aerosol injection in combination with plasma discharge [37; 38]. Indeed, in the context of the COVID pandemic and with the perspective of future applications in controlling the microbiota in tubes and tracheal appliances used in the respiratory tract,the anti-microbial efficacy of nebulized plasma activated water applied for 15 min shows the inactivation of _S. aureus_ and _E. coli_[39]. Publications dealing with resistant micro-organisms in the context of clinical protocol are much more scarce. Nevertheless, [PERSON] et al. [40] demonstrated that argon-based cold atmospheric plasma can serve as a potent treatment modality to reduce and even eradicate numbers of multidrug resistant pathogens colonizing patient' wounds. This outstanding work was performed with a \"plasma cold beam\" fed at 6 L/min with argon and resulting in a target plasma spot of about 5 mm in diameter. [PERSON] et al. [41] reviewed plasma applications in medicine with a special focus on dermatology. Among various topics, they report 291 treatments in 36 patients, and found a highly significant reduction in bacterial load in wounds treated with argon plasma compared with untreated wounds. This reduction was found in all types of bacteria, even in multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). Following these encouraging reports, there now exists a great interest in developing dedicated non-thermal plasma sources that are efficient and easy to implement in hospital or medical centers to face the critical challenges of nosocomial infection and chronic wounds. In this work, preliminary results are documented on the use of non-thermal plasma jets for bacterial load reduction in the context of chronic wound therapy. The following section presents the various plasma multi jet devices developed for this work and the bacterial targets used for the evaluation of the plasma decontamination opportunities. Afterward, in vitro decontamination assessments are presented and discussed for various pathogens, including resistant strains collected from patients at the Orleans hospital (CHRO). Finally, preliminary results obtained with low voltage plasma jets in the context of the toxicity evaluation for patients' treatment through a pilot study undergone at Orleans Regional Hospital in the department of Tropical and Infectious Diseases are briefly introduced.