Effects of hydrogel/silver coatings on in vitro adhesion to catheters of bacteria associated with urinary tract infections

Sections of sterile all-silicone-, hydrogel/silver-all-silicone-, and hydro ge/silver-latex-Foley urinary catheters were exposed to suspensions of bact eria and Candida albicans associated with urinary tract infections. The adh esion of these microorganisms to the catheters was determined with a radiol abel-cell procedure and scanning electron microscopy. Anomalous data with t he radiolabel procedure were produced with the hydrogel/silver-latex cathet ers for certain species. These aberrant data were related to adhesion on th e untreated cut ends of the latex catheter. Radiolabel-cell-adhesion proced ures that involve sections of coated materials may need to be supplemented with additional procedures such as scanning electron microscopy for valid i nterpretations of the data. Adhesion to the hydrogel/silver catheters by bo th Gram-positive- and Gram-negative bacteria most commonly associated with nosocomial urinary tract infections, including a strain of Pseudomonas aeru ginosa noted for its superior adhesion capacity, was significantly lower th an the adhesion to the control all-silicone catheter.