CSF1R and infection: In conclusion, we have described the KpGI-5 island which possessed a novel γ1-type CU operon called fim2. Although fim2 was shown to be expressed at an mRNA level and its function was investigated using three distinct murine infection models, tissue culture experiments and biofilm assays, no obvious in vitro or in vivo role for the fim2 locus was identified, although there were subtle hints of involvement in urovirulence and in bacterial dissemination from the respiratory tract.