Inhibition by dextran of Pseudomonas aeruginosa adherence to epithelial cells

Adherence of Pseudomonas aeruginosa to cells of the respiratory tract of patients with cystic fibrosis (CF) appears to be a necessary precondition for colonization and infection. To date no effective anti-adhesive strategy has been devised for preventing P. aeruginosa infection in these vulnerable hosts. The purpose of these studies was to evaluate the potential for preventing adhesion of P. aeruginosa to epithelial cells with dextran. Dextran (3,000-70,000 MW) inhibited adhesion of P. aeruginosa to buccal and A549 pulmonary epithelial cells; the 3,000 MW compound, at 10 mM was most inhibitory. Adhesion was inhibited optimally at pH 7.4 and was independent of charge; dextran and dextran sulfate were equally inhibitory. Dextran was most inhibitory if added to the epithelial cells before the P. aeruginosa; adhesion was reversed only minimally by adding dextran after the bacteria were bound. The inhibitory effect appeared to be nonspecific because other neutral polysaccharides (glycogen and mannan) were also inhibitory, dextran blocked attachment of other respiratory tract pathogens (Staphylococcus aureus, Group A streptococcus, and Haemophilus influenzae), and because dextran did not bind specifically to bacteria or to epithelial cells. Dextran is an inexpensive and nontoxic agent and may be useful in patients with CF to prevent colonization and infection with P. aeruginosa.