Nasal cytology: the "infectious spot", an expression of a morphological-chromatic biofilm.

The purpose of this study was to describe some "morphological-chromatic" patterns (i.e. spots of cyan colour) identified during the study of nasal cytology in patients with both bacterial and fungal infectious rhinological disorders. These peculiar aspects strongly suggest the presence of a microscopic biofilm. We retrospectively examined 1,410 nasal cytology specimens from subjects who underwent clinical-instrumental investigations (history, ENT visit, nasal endoscopy and nasal cytology) from January to August 2010. The control samples were represented by 30 subjects not suffering from infectious rhinological diseases. The presence of particular spots of "cyan" was found in colour in 107/1,410 rhinocytograms (7.6%), within which bacterial colonies and/or fungal spores were found. We called these coloured spot formations "infectious spots" (IS). The positivity to periodic acid Schiff (PAS) staining confirmed the polysaccharide nature of the coloured spots and allowed us to relate them to biofilms. This study demonstrates, for the first time, that nasal cytology performed by optical microscope can play an important role in detecting biofilms.