# Anti-Bacterial Action of Plasma Multi-Jets in the Context of Chronic Wound Healing
## 4 Discussion
In addition to the reactive species delivery, the bacteria on the central zone of the plasma jet impact zone may be inactivated during a short exposure as it is exposed to a rather intense electric field, while those on the more outer locations will require the accumulation of a larger number of lower strength electric field pulses and lower doses of reactive species. Similarly, and with regard to extended wound treatment, the use of the diffuse mode applicator (see Figure 8) or of the rotating (see Figure 7), linear (see Figure 10) and zigzag (see Figure 11) scanning protocols, demonstrates that large surfaces may be rather homogeneously decontaminated, extending the potentialities of plasma technology for these medical applications. Shorter treatment plasma exposure can indeed be developed on the basis of these multi jets scanning applicators. A few square centimeter large contaminated sample was inactivated for a single fraction of only a one-minute-long exposure. In the context of patient wound treatment, such short time exposure is an excellent indication of a highly tolerable therapeutic protocol, and may be envisioned as a daily fractionated treatment. Bacterial inactivation was demonstrated for _S. aureus_, _P. aeruginosa_ and drug resistant _S. aureus_, _P. aeruginosa_ and _E. coli_ strains collected for patients' wounds at Orleans hospital. Although not documented in this work, full decontamination was also achieved for the _S. dysgalactiae_ and _B. subtilis_ strains collected at Orleans Hospital. This confirms that plasma action has a broad spectrum target approach likely to be applied for various bacteria families, either gram positive or gram negative, even with the same plasma operation mode. It is also demonstrated that plasma multi jets can be a potent bactericidal agent for native or mature bacterial laws contaminated with a single but also a mix of various pathogens. Similar efficiency was demonstrated for antibiotic-resistant and non-resistant _P. aeruginosa_ (see Figure 9) as previously reported but for _E. coli_ bacteria and with dielectric barrier discharge applicator [33]. This strengthens the well-known unique status of plasma technology in comparison with conventional antibiotic drugs, as a broad spectrum and non-systemic, and thus likely a low side-effect, therapeutic option. Finally, the low voltage plasma applicator was used for the fractionated treatment of five wound-bearing patients with the focus on the scoring of the treatment tolerance and toxicity assessment. The plasma applicator was used for a few tens of minutes' exposures,by different nurses, and for wounds of various extensions, surface topologies, including necrotic, dry and humid zones. As summarized in Section 3.5, the tolerance scoring was excellent, with absolutely no pain, skin injury, inflammatory feeling or observed effects. While the study was focused on the tolerance and toxicity of plasma treatment, it was nevertheless observed, even with this limited patient cohort, a trend for the improvement of the tissue status on the plasma treated zones in comparison with the non-targeted zones for the same patients. Work is ongoing to assess the tolerance and healing efficiency of plasma multi-jets (either administered daily or each other day) delivered alone and in combination with dedicated dressings. This work is a new contribution in the development of plasma technology therapy for wound treatment, but as expressed in the conclusion of [40], \"the possible role of cold atmospheric pressure plasma in clinical multi drug resistant decontamination must be evaluated in clinical trials with repeated plasma treatment embedded in a comprehensive hygienic decontamination concept\". This mandatory step is planned in collaboration with CHRO. This work demonstrates that the on-demand design of multi jets applicators can be performed for the development of various plasma applicator sizes and shapes with various numbers and spatial distributions of the multi jets likely covering very extended surfaces.