An In Vitro Model Using TRIS-Buffered Plasma-Activated Water to Reduce Pathogenic Microorganisms Involved in Digital Dermatitis Infection in Cattle

Bovine digital dermatitis is an important infectious claw disease caused by multimicrobial infections with bacteria such as Fusobacterium (F.) necrophorum or Porphyromonas (P.) levii. To analyze the antibacterial effects of a TRIS-buffered plasma-activated water (Tb-PAW) on the bacterial number of F. necrophorum, P. levii, Escherichia (E.) coli, Staphylococcus (S.) aureus and Clostridium (C.) sporogenes 1 mL of each bacterial solution (106–108 CFU/mL) was incubated with 9 mL Tb-PAW up to 15 min. E. coli, F. necrophorum and P. levii were significantly reduced by 5.0 log after 1 min of treatment, while S. aureus and C. sporogenes required 15 min to reach a 3.0 log reduction. The addition of bovine serum albumin did not negatively affect the bactericidal effect. Tb-PAW storage at 7 °C and 21 °C is possible for up to 24 h without any change in the bactericidal effect, while Tb-PAW stored at 30 °C can only be used for a period of 12 h. The present data indicate that Tb-PAW can be used to reduce various bacteria even under the influence of different parameters. However, due to the complexity of Tb-PAW, further studies are required to ensure its microbicidal activity before practical application.