Adhesion of Pseudomonas aeruginosa to silicone rubber in a parallel plate flow chamber in the absence and presence of nutrient broth

The physico-chemical cell-surface properties of Pseudomonas aeruginosa AK1 and its adhesion to silicone rubber under flow were compared for cells suspended in phosphate-buffered saline (PBS) or PBS supplemented with 2% nutrient broth. Addition of 2% nutrient broth to cells suspended in PBS yielded minimal growth and did not significantly change the mean zeta potential of the organisms, which was around -13 mV. However, a comparatively larger proportion of the organisms had more negative zeta potentials in the presence of nutrient broth. This change was concurrent with a slight decrease in cell-surface hydrophobicity, as measured by water contact angles, from 119 degrees to around 112 degrees. The initial deposition rate of P. aeruginosa AK1 to silicone rubber, as studied in a parallel plate flow chamber, increased from 344 cm(-2) s(-1) in the absence of nutrient broth to 505 cm(-2) s(-1) in its presence. No stationary level of adhesion was observed in the presence of nutrient broth, instead the number of adhering cells increased steadily at a rate of approximately 85 cm(-2) s(-1). Fluorescent staining of adhering cells demonstrated that for adhesion from buffer only 2% of the adhering cells were metabolically active, whereas in case of deposition from PBS supplemented with nutrient broth, 67% of the adhering cells were metabolically active. It is concluded that the deposition rates measured in the parallel plate flow chamber with 2% nutrient broth added to the PBS suspension represent an interplay of adhesion and surface-associated growth

Adsorption of urinary components influences the zeta potential of uropathogen surfaces

Zeta potential distributions of five uropathogens were measured in urines collected after increased water intake, consumption of cranberry supplements, or intake of ascorbic acid by volunteers. Zeta potentials of bacteria in urine from ascorbic acid consumption shifted towards less negative values due to pH changes. Cranberry supplementation caused a shift in zeta potential distribution in a more positive direction possibly due to fructose and tannin metabolites, which are known to influence bacterial adhesion. The most negatively charged sub-populations of bacteria disappeared after increased water intake, believed to be caused by dilution of Tamm Horsfall Protein (THP). It is concluded that THP may adsorb to uropathogen cell surfaces to yield a more negative zeta potential, which thereby reduces uropathogen adhesion to surfaces through electrostatic repulsion. The ability to alter uropathogen cell surface properties by delivery of functional foods could have clinical significance in the pathogenesis and prevention of urinary tract infections. (C) 2000 Elsevier Science B.V. All rights reserved

The effect of water, ascorbic acid, and cranberry derived supplementation on human urine and uropathogen adhesion to silicone rubber

In this study, urine was collected from groups of volunteers following the consumption of water, ascorbic acid, or cranberry supplements. Only ascorbic acid intake consistently produced acidic urine. Photospectroscopy data indicated that increased water consumption produced urine with lower protein content. Surface tension measurements of the collected urine showed that both water and cranberry supplementation consistently produced urine with surface tensions higher than the control or urine collected following ascorbic acid intake. These urine samples were also employed to study uropathogen adhesion to silicone rubber in a parallel plate flow chamber. Urine obtained after ascorbic acid or cranberry supplementation reduced the initial deposition rates and numbers of adherent Escherichia coli and Enterococcus faecalis, but not Pseudomonas aeruginosa, Staphylococcus epidermidis, or Candida albicans. Conversely, urine obtained from subjects with increased water intake vastly increased the initial deposition rates and numbers of adherent E. coli and E. faecalis (P <0.05)