Inhibition of Staphylococcus aureus and Pseudomonas aeruginosa biofilms by quatsomes in low concentrations

Staphylococcus aureus and Pseudomonas aeruginosa are primary pathogens in chronic rhinosinusitis (CRS), and the presence of S. aureus and P. aeruginosa biofilms has been associated with negative outcomes after surgery. This study investigated the inhibition effect of cetylpyridinium chloride (CPC)-quatsomes at low concentrations on both S. aureus and P. aeruginosa biofilms in vitro , as well as their toxicities towards cultured human airway epithelial (NuLi-1) cells. S. aureus ATCC 25923 and P. aeruginosa ATCC 15692 were used to establish biofilms. CPC-quatsome and CPC micelle solutions at concentrations of 0.01%, 0.025%, and 0.05% were prepared. AlamarBlue was used to test the viability of both planktonic S. aureus and P. aeruginosa and their biofilms after treatment for 5 min and 2 h, respectively. Confocal laser scanning microscopy (CLSM) was used to investigate the interactions between CPC-quatsomes and S. aureus and P. aeruginosa biofilms. A lactate dehydrogenase (LDH) assay was used to determine the toxicity of CPC-quatsomes on NuLi-1 cells. CPC-quatsome and CPC micelle solutions had significant inhibition effects at all tested concentrations on planktonic S. aureus and P. aeruginosa and their biofilms after 5-min exposure (P  <  0.05). In the CLSM study, different interactions between CPC-quatsomes and S. aureus or P. aeruginosa biofilms were observed. After 2-h treatment, the size of S. aureus biofilms decreased, while the number of dead bacteria increased in P. aeruginosa biofilms. Neither CPC-quatsomes nor CPC micelle solutions showed significant toxicity on NuLi-1 cell at all tested CPC concentrations (P  <  0.05). CPC-quatsomes at low concentrations inhibited S. aureus and P. aeruginosa in both planktonic form and biofilms. No adverse effects on NuLi-1 cells were observed, indicating their promising potential in the treatment of CRS.