Linkage between cellular adherence and biofilm formation in Escherichia coli O157:H7 EDL933

During the establishment of Escherichia coli O157:H7 infection, its capacity to adhere to host intestinal epithelial cells is the critical first step in pathogenesis. It also has the capability to form biofilms, and because both are surface activities, we sought to gain insight into a potential linkage between biofilm formation and adherence to epithelial cells. We conducted an adherence assay with 51 biofilm-negative mutants and two human epithelial cell lines, T84 and HEp2. Our results show that unlike wild-type cells, biofilm-negative mutants adhere poorly to epithelial cells. Some adhesin-negative mutants were fully competent in biofilm formation, however. Thus, biofilm-forming activity in E. coli O157:H7 EDL933 is required for adherence to T84 and HEp2 cells, but it is not sufficient.