Assessment of the Antimicrobial Effect of Non-Thermal Plasma Activated Water Against Coagulase-Positive Staphylococci

Abstract

Coagulase-positive staphylococci, the main etiologic agents of pyodermatitis have a well-known ability to develop multi antibiotic resistance mechanisms. Non-thermal plasma activated water (PAW) is a new generation of disinfectants/decontaminants so-called “non-conventional” highly efficient against the microorganisms of medical interest.Since the plasma discharge in water gives it specific physical and chemical properties, including bactericidal activity, the purpose of our paper was to evaluate the degree of reduction of the microbial burden after the exposure to PAW of coagulase-positive staphylococci suspensions.Evaluation of the antimicrobial effect was performed on 38 strains of coagulase-positive staphylococci isolated from skin lesions in humans and pets. In order to obtain PAW, a GlidArc reactor was used. A defined volume of staphylococcal suspension (10 ml) with 3 McFarland density (approx. 109 CFU/ml) was mixed with 90 ml PAW and after various contact times (3, 5, 7 and 10 minutes) known volumes of the mixture (0.1 and 1.0 ml) were transferred to Baird-Parker Agar plates in order to determine the number of CFU/ml. In parallel, the initial burden was determined by serial dilution method. The reduction of the bacterial burden was calculated as the log [(CFU/ml before treatment)/(CFU/ ml after treatment)].After 3 minutes contact with PAW, the average burden reduction was 5.00 log10. After 10 minutes of treatment, the initial burden has been reduced with an average of 7.61 logarithmic units.PAW proved to be a powerful anti-staphylococcal agent and further in vivo studies are warranted to demonstrate its therapeutic benefits in different clinical dermatological conditions.