Elizabeth Ruder

Pseudomonas aeruginosa is an opportunistic human pathogen that can be antibiotic-resistant and can pose challenges for treating infections in several conditions including chronic burn wound patients. Due to the increase in the occurrence of resistant strains, alternative treatments to antibiotics are needed. Here, we are exploring the use of dielectric barrier discharge (DBD) non-thermal plasma. Plasma treatment was shown to kill bacterial cells, and this is hypothesized to occur through the generation of free radicals. However, the efficacy of plasma treatment on antibiotic resistant strains is poorly understood, and the effect of the treatment on the antibiotic resistance profile is unknown. To answer these questions, plasma-treated P. aeruginosa was treated with ofloxacin and sulfathiazole to test if plasma treatment increases antibiotic susceptibility. Our results show that the combined treatment of the cells with both ofloxacin and plasma had greater killing than with ofloxacin or plasma alone; we termed this effect to be synergistic. Conversely, sulfathiazole, when combined with plasma treatment, did not result in any change in the killing of cells. The initial results with ofloxacin and sulfathiazole prompted a further screening of 48 antibiotics in conjunction with plasma treatment. Results suggest three groups of antibiotics: molecules with synergistic effects to plasma, molecules with little to no effect on growth (due to resistance), and a small group of antibiotics that had antagonistic effects to plasma treatment. The screening yielded promising targets for further exploration of antibiotics to combine with plasma treatment to challenge the antibiotic resistance of P. aeruginosa.