R-plasmid RP1 promotes adhesion of gram-negative bacteria to medical prostheses and glass.

The presence of R-plasmid RP1 increased the adhesion of chemostat-grown iron- and carbon-limited Proteus mirabilis to the surfaces of various medical prostheses and to glass. Similar results were obtained with iron-limited Pseudomonas aeruginosa and anaerobically-grown Escherichia coli. Changes in the surface properties of P. mirabilis indicated that the R-plasmid-mediated increase in negative charge was one of the factors that promoted adhesion.