The right answers is: Virulence Factors.
Besides intoxinations, the first stage of pathogenicity is the colonization of the host at the gateway.
One of the factors is adhesion to mucosal epithelial cells using pili or non-fibrillar adhesins. The adhesin of the pili is located within fimbriae. This adhesin is the molecule that will interact with a receptor on the cells of the host. In the case of non-fibrillar adhesins, the protein is located on the outer membrane of the bacteria. In some cases (enteropathogenic Escherichia coli), this receptor is secreted by the bacterium inside the cytoplasm of the host cells.
Once the gateway is colonized, several types of pathogenicity can be expressed.