Direct confocal microscopy studies of the bacterial colonization in vitro of a silver-coated heart valve sewing cuff.

The antimicrobial coating of prosthetic heart valve sewing cuffs has been considered a potentially effective method for preventing prosthetic valve endocarditis. Although traditional in vitro bacterial adherence studies are often useful as screening tools, they can be inadequate in examining the antiinfective efficacy of antimicrobial-coated devices. We conducted a pilot in vitro study to directly assess the antimicrobial activity of a silver-coated sewing cuff versus uncoated cuff using confocal scanning laser microscopy. Staphylococcus epidermidis adhered more to the surfaces of the silver-coated sewing cuff compared with the uncoated cuff. These pilot in vitro results cast a doubt on the antiinfective efficacy of silver-coated prosthetic heart valve sewing cuffs and suggest further assessment should be carried out using animal studies.