• Staphylococcus aureus
• biofilm
• persister cells
• biofilm matrix

Biofilm infections are a very dangerous problem for public health and Staphylococcus aureus is at the forefront of causing these infections. One of the main abilities of this bacterial species is to orchestrate the deposition of human host extracellular matrix proteins. However, not all bacteria in the biofilm population take part in this process: a very small fraction of cells, persister cells, turn off their metabolism becoming tolerant towards external agents such as antibiotics. This guarantees the population the opportunity to form again if a catastrophic event kills all the cells with a non-persister phenotype. The focus of the experimental project presented in this thesis was to verify whether the different fluorescence intensity associated with GFP transformed into S. aureus, could allow the distinction between persister and non-persister cells at the confocal microscope. Finding a methodology to easily discriminate persisters is important to deepen the knowledge about this cell phenotype, cause of the difficulties in the complete eradication of infections caused by S. aureus.