Physico-chemical cell surface properties of 23 coagulase-negative staphylococcal strains, including contact angles, zeta potentials and elemental cell surface composition were measured, together with the adhesion of all strains to hexadecane. The data were employed in a hierarchical cluster analysis, revealing that the 23 strains comprised essentially four different groups. Groups I-III were somewhat similar to each other, but group IV was markedly distinguished from the other strains, predominantly through an elevated acidity of the cell surface. These group distinctions were not related to the presence of a capsule or slime on the strains. Adhesion of the strains to hexadecane depended critically on electrostatic interactions between the hexadecane and the staphylococci, and adhesion only occurred when the electrostatic repulsion between hexadecane and the micro-organisms was less than 500 kT at closest approach. Adhesion of six representative strains from all four groups in a parallel plate flow chamber to silicone rubber, an implant material with similar hydrophobicity to hexadecane, did not show such a critical dependence, nor did it relate with the group distinction Possibly microbial adhesion to substratum surfaces like silicone rubber is more complicated than adhesion to an ideally smooth and homogeneous hexadecane surface in an aqueous solution. Adhesion of all six strains to silicone rubber with an adsorbed conditioning film of plasma proteins was less than that to bare silicone rubber: initial deposition rates dropped from 2000-3000 cm s to 100-300 cm s after adsorption of plasma proteins, while the stationary end-point adhesion decreased from 10 x 10-15 x 10 cm to 1 x 10-5 x 10 cm. The adhering staphylococci poorly withstood the passage of an air-bubble through the parallel plate flow chamber regard! of the presence of a conditioning film, indicating a low affinity of these relatively hydrophilic strains for hydrophobic substratum surfaces.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error