Characterization of Pseudomonas aeruginosa adherence to cultured hamster tracheal epithelial cells

This study reports an in vitro system that allows the convenient study of both microenvironmental and bacterial factors affecting adherence of Pseudomonas aeruginosa to tracheal epithelium. Primary cultures of mixed ciliated and nonciliated epithelial cells isolated from hamster tracheas were grown on collagen-coated multiwell plates containing 10(5) epithelial cells/well at confluence. When 10(7) 14C-labeled P. aeruginosa (nonmucoid, strain Y-4) suspensions were added to each well, 8.13 +/- 2.6% (mean +/- SD) of the initial inoculum bound to the cultured cells, an amount comparable to that measured using suspensions of human tracheal epithelial cells and the same bacteria. The bacteria adhered preferentially to the cultured cells rather than to an acellular collagen matrix. Five additional nonmucoid strains of P. aeruginosa also bound well to the cultured cells, while two mucoid strains were less adherent. Strains of two other gram-negative bacteria, Pseudomonas maltophilia and Klebsiella pneumoniae, did not bind significantly, emphasizing the bacterial species specificity of the adherence interaction being measured. The binding interaction with P. aeruginosa was both pH-sensitive and altered by the presence of the divalent cation calcium. Thus, the in vitro assay system described provides a consistent surface of tracheal epithelial cells that binds P. aeruginosa in a specific manner and can be used to examine the effects of bacterial variables and microenvironmental conditions that may be present in the human airway.