Study of cell surface hydrophobicity and its correlation with bacterial adherence capacity to catheter sections

Abstract number: 903_r2119

Lazar V.


Generally, bacteria with hydrofobic surface are less adherent to the cellular substratum, but they are intensively adherent to hydrofobic materials causing medical devices associated infections, very difficult to treat because their phenotypic resistance to antibiotics.


Determining cell hydrophobicity of 10 selected enterobacteria opportunistic strains with different isolation sources (previously tested for adhesion and invasion on cellular substratum) and to investigate the adherence capacity to an hydrophobic substratum (poliuretan silicon coated catheter sections).

Material and methods:

Bonner's method (1997) is based on the spectrophotometric assay of bacterial suspensions capacity to mix with organic solvents and to pass from the aquatic phase to the organic one, having as consequence the decrease of optic density in the aquatic phase. The adherence capacity to an inert substratum was tested in vitro on a model in 24 – multi-well plate, incubating the catheter sections with bacterial suspensions. After incubation, the catheter pieces were washed in sterile PBS, fresh medium was added, further incubated for 24 h and the optic density of the bacterial cultures was assayed. An Enterobacter cloacae strain, selected for its intense adherence capacity to a cellular substratum, also proved to be moderately hydrophobic and was studied for its interaction with catheter surface by SEM. With this aim, bacterial culture on nutrient broth was introduced in a circuit including a fragment of catheter and recirculated with a peristaltic pump. After 24 h, the catheter was removed and examined by SEM.


Our study demonstrated that cell surface hydrophobicity promotes strong bacterial adherence capacity to the hydrophobic, inert substratum represented by plastic catheter. SEM results demonstrated that an opportunistic enterobacterial strain isolated from food could become an aetiologic agent of prosthetic devices associated infections due to its adherence capacity to the inert substratum and to its capacity to form biofilms.


The hydrophobic bacterial surface, even moderate, could constitute a virulence feature of opportunistic enterobacteria. In this sense, an Enterobacter cloacae (43) strain isolated from food and previously proved to be able to generate A/E lesions on a cellular substratum was also able to adhere and to form biofilms to the internal surface of a catheter fragment, as SEM results clearly demonstrated.


Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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