Kinetics of adherence of mucoid and non-mucoid Pseudomonas aeruginosa to plastic catheters.

The adherence of six non-mucoid and three mucoid strains of Pseudomonas aeruginosa to polyvinyl chloride (PVC), polyurethane (PU) and siliconised latex (SL) was evaluated by a radiometric method and scanning electronmicroscopy. Initially greater numbers of mucoid than non-mucoid strains adhered to all three materials. Hydrophobic non-mucoid strains adhered more efficiently than hydrophilic strains. Numbers of adherent non-mucoid P. aeruginosa cells increased with time, reaching a peak, which was different for each strain, at 1-4 h for PU, 4 h-2 days for SL and 2-3 days for PVC; thereafter a gradual decrease was observed, maximal and final values of adherence being higher with PVC and SL than with PU. Adherence of mucoid strains increased with time in 3-5 days, until a steady state was reached. We conclude that although non-mucoid strains of P. aeruginosa initially colonise plastic surfaces better than mucoid strains, mucoid strains also persist on these surfaces.