Bacterial Pathogenesis

Yashuan Chao, Caroline Bergenfelz, Anders P. Håkansson

Pontus Nordenfelt, Mattias Collin

This manuscript presents novel approaches to grow and evaluate Streptococcal biofilm formation using the human respiratory pathogen Streptococcus pneumoniae (the pneumococcus) as the main model organism on biological surfaces in vitro and in vivo. Most biofilm models are based on growth on abiotic surfaces, which is relevant for many pathogens whose growth on surfaces or medical devices is a major cause of disease transmission and infections, especially in hospital environments. However, most infections with commensal organisms require biofilm formation on biological surfaces in the host at the site of colonization or infection. In vitro model systems incorporating biological components from the host and taking into account the host environment of the infectious site are not well described.In a series of publications, we have shown that S. pneumoniae form complex biofilms in the nasopharynx of mice and have devised methodology to evaluate the biofilm structure and function in this environment. We have also been able to recapitulate this biofilm phenotype in vitro by incorporating crucial factors associated with the host environment. Although the protocols presented in this manuscript are focused on S. pneumoniae, the same methodology can and has been used for other Streptococcal species that form biofilms on mucosal surfaces.