In vitro antimicrobial activity of cold atmospheric microwave plasma against bacteria causing canine skin and ear infections

Abstract

Background Cold atmospheric plasma (CAP) is a new generation medical therapeutic option for bacterial infections. CAP causes physical cell wall rupture and DNA damage, therefore making it highly useful in the treatment of various conditions such as skin infections. Hypothesis/objectives The antimicrobial activity of cold atmospheric microwave plasma (CAMP) against major strains in canine skin infections was tested and the difference in antimicrobial activity between the antibiotic‐resistant and antibiotic‐susceptible strains of Staphylococcus pseudintermedius was evaluated. Methods and materials American Type Culture Collection (ATCC) strains (Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli) and clinical isolates identified as methicillin‐resistant S. pseudintermedius (n = 27) and methicillin‐susceptible S. pseudintermedius (n = 13) were exposed to CAMP for 10 s, 30 s and 60 s. Afterwards, the bacterial survival rate was confirmed. Results Gram‐negative bacteria (P. aeruginosa and E. coli) were more susceptible than Gram‐positive bacteria (S. aureus and S. pseudintermedius) for the same duration of CAMP exposure. Only the Gram‐negative bacteria were completely killed after 60 s exposure. In S. pseudintermedius isolates, CAMP exposure had similar antibacterial effects regardless of antibiotic resistance. Conclusions and clinical importance CAMP has sufficient antimicrobial activity against major bacterial strains that cause pyoderma and otitis externa in dogs, and may be an alternative therapeutic option for S. pseudintermedius skin infections, for which antibiotics often are ineffective because of antimicrobial resistance in clinical veterinary medicine.

Evaluation of cold atmospheric microwave plasma on skin physiological parameters and tolerability in dogs

“…This interval makes it difficult to know the temperature immediately after CAMP application and how rapidly it might have changed. The antimicrobial effects of CAMP were demonstrated previously 16 in a shorter time period and a larger area (<60 s, 9.6 cm 2 ) than used herein (<4 min, 2.25 cm 2 ). Therefore, it appears that with a short application time per area, simultaneously obtaining sufficient antimicrobial effects and preventing thermal damage is possible.…”

“…A previous study has proven its antibacterial activity against bacterial strains frequently encountered in canine bite wounds in vitro 20 . In addition, a study confirmed the considerable antibacterial and antibiofilm effect of CAMP against bacteria frequently associated with pyoderma and otitis externa in dogs 16, 17 …”

“…A CAMP device (Bio Stimulation Microwave Plasma v1.0, IonMedical Inc.) was used in this experiment (Figure 1a). Using nonionised argon gas as a carrier gas, plasma was produced inside a cylinder by microwave energy application (30–50 W, 2450 MHz) 9, 16, 17 . Subsequently, plasma was ignited and emitted through the nozzle and delivered to the target site.…”

“…The microwave energy could be adjusted to 30–50 W, and the flow rate of the argon gas could be adjusted 10–20 L/min. The length of the plasma jet also was influenced by the power consumption, varying between 3 and 15 mm 16, 17 . At a gas flow rate of 15 L/min and with a power consumption of 30 W, the effluent had a visible length of 10 mm and the surface temperature of the plasma was maintained at <40°C.…”

“…Using nonionised argon gas as a carrier gas, plasma was produced inside a cylinder by microwave energy application (30-50 W, 2450 MHz). 9,16,17 Subsequently, plasma was ignited and emitted through the nozzle and delivered to the target site. The plasma emission could be changed depending on the power consumption and gas velocity.…”