Improving effects of low-temperature atmospheric plasma on abdominal surgical site infection induced by ESBL-E. coli in rats

Surgical site infection (SSI) is one of the most common complications of emergency abdominal surgery. With the increase of drug-resistant bacteria, abdominal SSI cannot be effectively controlled by increasing the use of antibiotics. Nonchemical treatment as an alternative to antibiotics for abdominal SSI induced by drug-resistant bacteria is urgently needed. This study is aimed at exploring the effects of low-temperature atmospheric plasma (LTAP) exposure for 30 and 60 s on abdominal SSI in in vitro and in vivo experiments. In the in vitro experiment, the culture dishes with extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E. coli) were exposed to LTAP and the changes in bacterial concentration and structure were observed by bacterial culture counting and transmission electron microscopy (TEM). In in vivo experiments, we established an abdominal SSI rat model induced by ESBL-E. coli and the infected surgical sites were exposed to LTAP. The infiltration of inflammatory cells, the proliferation of fibroblasts, and the regeneration of fibrous tissue were evaluated by histopathological examination. The in vitro bacterial experiment showed that the concentration of bacteria exposed to LTAP for 30 and 60 s was decreased, and the decline in bacterial concentration in the last 30 s was significantly higher than that in the first 30 s. TEM showed that the bactericidal effect of the LTAP exposure worked by damaging the morphology and intracellular structures of bacteria. In addition, our data suggested that reactive oxygen species are the key mediator of the bactericidal effect, and bacteria exposed to LTAP do not develop resistance to repeated exposure. The pathological results from in vivo experiments revealed that the inflammatory cells infiltrating into the infected site were inhibited. The proliferation of fibroblasts and the regeneration of fibers increased after exposure to LTAP for 30 and 60 s in abdominal SSI. In conclusion, our study indicated that LTAP was effective in wound sterilization, anti-inflammatory action, and healing promotion and holds promise as an alternative to antibiotics for treating abdominal SSIs.