SGCG and bacterial urinary tract infection: To investigate the role of type 1 and type 3 fimbriae in K. pneumoniae biofilm formation a well-defined isogenic type 1 fimbriae mutant (C3091Δfim), a type 3 fimbriae mutant (C3091Δmrk), and a type 1 and 3 fimbriae double mutant (C3091ΔfimΔmrk) of the clinical UTI isolate C3091 were used.