A major virulence factor of a common human pathogen Pseudomonas aeruginosa, was investigated to determine if it dominated attachment interactions in a variety of in vitro cell culture systems. It was found that Type-IV pilus-type mechanisms, which mediated the attachment of P. aeruginosa to three human respiratory tract cell lines (A549, BEAS-2B and RPMI 2650) also mediated attachment to two respiratory tract cell lines from mouse (C57) and rat (L-2) to a similar degree. Significant differences were found in the number of P. aeruginosa associated with the human, rat and mouse cell lines. Additionally, differences were also found between A547, C57 and L-2 cells with respect to the moieties that P. aeruginosa interacted with at the level of the cell surface, suggesting that asialo-GM1 ligands were not the only structure that this bacterium could interact with in order to associate with host cells.