The COMSTAT results for both the type 3 fimbriae mutant and type 1 and 3 fimbriae double mutant revealed much lower this website substratum coverage than the wild type. This indicates that type 3 fimbriae are most important for initial
cell-surface attachment. Furthermore, the lower amount of biomass and average thickness of the biofilms for the type 3 fimbriae mutants compared to the wild type and type 1 fimbriae mutant indicates that type 3 fimbriae also mediates cell-cell adherence in the biofilm. Our results confirm previous find more studies demonstrating that type 3 fimbriae are important for K. pneumoniae biofilm formation [29, 33]. Also in E. coli , the recently discovered ability to express type 3 fimbriae, mediated by conjugative plasmids, was found to profoundly enhance biofilm formation [16, 17]. Thus, type 3 fimbriae expression seems to generally promote biofilm formation in different bacterial species. We have previously established that type 1 fimbriae but not type 3 fimbriae are an essential virulence factor in K. pneumoniae urinary tract infections [18, 19]. The present study demonstrates how the impact of a specific virulence factor may vary significantly in different infection scenarios and host environments. Thus, although type 3 fimbriae may
not be significantly involved in development of uncomplicated UTIs, our results indicates that type 3 fimbriae may be a significant virulence factor in CAUTIs since they promote biofilm formation Target Selective Inhibitor Library ic50 on inert surfaces. Understanding the mode of bacterial growth in vivo during Fossariinae infection is important in relation to future therapeutic measures. Conclusions In conclusion, the present work shows that type 3 fimbriae, but not type 1 fimbriae, mediate biofilm formation in K. pneumoniae C3091. As type 3 fimbriae promote adhesion to abiotic surfaces and biofilm formation in K. pneumoniae and other species, as shown here and by other studies [16, 17, 29, 33], type
3 fimbriae may generally play a significant role in development of catheter related infections such as CAUTIs. In this respect, the occurrences of conjugative plasmids encoding type 3 fimbriae in other species are worrisome. As the vast majority of K. pneumoniae isolates are able to express both type 1 and type 3 fimbriae [1], the use of epidemiological studies to elucidate the role of fimbriae in catheter associated K. pneumoniae infections is difficult. Thus further studies using catheterized in vivo infection models, are needed to further characterize the role of fimbriae in catheter related infections. Acknowledgements C. Struve was partially financed by Danish Research Agency Grant 2052-03-0013. We would like to thank Professor Søren Molin, Centre for Biomedical Microbiology, Technical University of Denmark, 2800 Lyngby, Denmark, for providing flow chamber facilities. References 1. Podschun R, Ullmann U: Klebsiella spp .