Effect of phosphonium-based ionic liquid against mixed biofilm of <i>Candida albicans</i> and methicillin-resistant <i>Staphylococcus haemolyticus</i> 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 <i>Candida albicans</i> and methicillin-resistant <i>Staphylococcus haemolyticus</i> (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 <i>Candida albicans</i> 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.