Pathogenesis of intravascular device-related infections

Important pathogenic factors for catheter contamination are related to (1) the properties of the material constituting the device, (2) host factors, and (3) the intrinsic virulence factors of the involved microorganisms (ability to form biofilm). In Table 12.3, the factors controlling microbial adhesion to abiotic surfaces are listed. 

Chemical properties of the surface Hydrophobicity/hydrophiUcity Polar groups Charged groups 

Environmental conditions Host protein conditioning layer Shear rate pH and temperature 

Pathogen Gram positive/Gram negative Genus/species Surface charge Ability to form biofilm 

Tegoulia and Cooper studied S. aureus adhesion on self-assembled monolayers terminated with methyl, hydroxyl, carboxylic acid, and tri(ethylene oxide) groups. Results showed how bacterial adhesion was lower on the hydrophilic ethylene oxide-bearing and hydroxyl-bearing surfaces. However, preincubation of surfaces with fibrinogen increased microbial adhesion on all surfaces and minimized the effect of the surface properties of the substrate. The authors concluded that even if surfaces rich in ethylene oxide groups can be used to prevent bacterial adhesion under physiological conditions, most of the substrate properties are masked and their effect on adhesion becomes minimal. 

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