Anti-virulence potential of carvone against Serratia marcescens

Serratia marcescens is a common opportunistic pathogen that causes infections in clinical patients. The aim of this study was to investigate the inhibitory efficiency of carvone on the production of virulence factors and evaluated the susceptibility of antibiotics against biofilms of S. marcescens in combination with carvone. Carvone treatment notably inhibited the production of lipase, prodigiosin, extracellular polysaccharides (EPS), and swimming and swarming motilities. Carvone exposure also reduced the formation of biofilms in S. marcescens NJ01. When exposed to antibiotics in combination with carvone, the inhibitory impact was notably improved. In addition, the expressions of genes glp and katG involved in the synthesis of glutathione peroxidase and catalase, respectively, were significantly suppressed after treatment with carvone. The suppression of antioxidant enzymes resulted in the improvement of reactive oxygen species (ROS) and H₂O₂, enhanced the permeability of membrane, and eventually increased the susceptibility of biofilms or planktonic cells to antibiotics. The data mentioned above indicated that carvone is expected to play an important role in the control and treatment of S. marcescns infection.