In case of bacteria, biofilm production is one representation of the so called quorum sensing, also known as local density sensing. When the size of the population exceeds a threshold value, gene expression changes, and bacteria and fungi will produce biofilms, that can protect the population from environmental effects (e.g. antibiotics, antifungal agents).
In our studies, primarily Pseudomonas aeruginosa and Malassezia pachydermatis strains are investigated. Their susceptibility is compared between their biofilm producing and planctonic (non-biofilm producing) forms. The studies are conducted with the catheter adhesion methodology, taking into account the CLSI (Clinical Laboratory Standards Institute) microdilution method. In our studies, the simple, unaided eye examinations are complemented with vital staining and their photometric evaluation.