Effect of phosphonium-based ionic liquid against mixed biofilm of Candida albicans and methicillin-resistant Staphylococcus haemolyticus isolated from hemodialysis catheter: assessment using confocal raman mapping and microscopic imaging

The emergence of multidrug-resistant pathogens linked to mixed biofilm infections is a significant concern due to limited therapeutic options. This health risk has renewed interest in developing new antibiofilm alternatives. In this study, the antibiofilm potential of a phosphonium-based ionic liquid against a mixed-species biofilm of Candida albicans and methicillin-resistant Staphylococcus haemolyticus (MRSH) was assessed preliminarily using the microbroth dilution assay. The ionic liquid inhibitory profiles were further explored by confocal Raman mapping, scanning electron microscopy (SEM), and fluorescence microscopy (FM). A substantial antibiofilm effect was demonstrated. Raman mapping showed a modified biofilm distribution following ionic liquid treatment, demonstrating the differential inhibitory effects between strains in mixed biofilm. Additionally, FM revealed that the morphological switching of Candida albicans was inhibited, while SEM revealed a disruption of biofilm integrity. On the other hand, the hemolysis test showed the safety profile of the ionic liquid by exhibiting low cytotoxicity at active concentrations.