Chronic rhinosinusitis with nasal polypis is a disease of unknown etiology. Bacterial infection is apparently one of etiological factors participating in etiopathogenesis. The information about bacteria helps the clinician to gain a new and interesting view of the chronic rhinosinusitis. Bacteria possess exceptionally good ability of adaptation and, under certain conditions, can create community, where they collaborate and can modify their phenotype; moreover, pathogenic bacteria have various factors of virulence, which affect the host and enable a protection against immune reactions of the host. All these properties participate in the development of chronic bacterial infection caused by Staphylococcus aureus, which has been the most often proved pathogen in patients with chronic rhinosinusitis.

        Key words: Staphylococcus aureus, biofilm, chronic rhinosinusitis.