Purpose: Decontamination efficacy of a 2D-air-based DBD-plasma microdischarge array (2D-AMPA) against a multidrug resistant (MDR) SH isolate on stainless steel, romaine lettuce, and chicken breast was studied.
Methods: Samples (stainless steel discs, lettuce leaves, and pieces of chicken breast) were spiked with ~6.5 log CFU of MDR SH culture. After drying, the samples were exposed to the 2D-AMPA for one to 10 min at 10 cm distance and at optimal operational conditions. The surviving bacterial cells at each time were counted by plating serial 10-fold dilutions onto tryptic soy agar plates. The reduction in bacterial numbers was calculated by difference between bacterial counts with and without AMPA treatments.
Results: A complete reduction in bacterial counts (> six log CFU/ one cm² sample surface) was attained after four minutes exposure on stainless steel surfaces. However, complete reduction was not attained on lettuce and chicken breast even after 10 min of exposure. After five minutes exposure, ca. four and ca. three log reductions were seen on lettuce and chicken, respectively. A possible reason could be that the antibacterial efficacy of plasma decreases on organic and proteinaceous surfaces.
Significance: While plasma inactivation of Salmonella has been assessed previously, this was the first analysis of the efficacy of plasma inactivation of MDR SH on different foods and a food contact surface. The results showed that our cost-effective 2D-AMPA setup, which produces plasma at low power from air, is promising as an alternative technology for destroying MDR pathogens on poultry, fresh produce, and food contact surfaces.