For both colonization and pathogenesis, the first essential step is adherence to mucosal epithelial cells. Many investigations have shown bacterial targeting of specific human signalling molecules such as integrins, sialic acid binding Ig like lectins (Siglecs) and carcinoembryonic antigen (CEA)-related cell adhesion molecules (CEACAMs) can lead to cellular invasion (Virji et al., 1995; 1999; Hauck and Meyer, 2003; Jones et al., 2003) . Of these, CEACAMs have emerged as common targets of several respiratory mucosal pathogens and include Nm, Hi, Moraxella catarrhalis, as well as the urogenital pathogen Neisseria gonorrhoeae and enteric pathogens Escherichia coli and Salmonella (Leusch et al., 1991; Virji et al., 1996a; Chen et al., 1997; Gray-Owen et al., 1997; Hill and Virji, 2003) .