Biofilm formation on clinically noninfected penile prostheses

Biofilms are matrix enclosed bacterial populations that adhere to each other and/or to surfaces of implanted medical devices. Biofilm formation has consistently been demonstrated in association with infected penile prosthetic material. Clinically noninfected patients undergoing revision for mechanical malfunction have a surprisingly high rate of positive intraoperative cultures. After revision replacement prostheses have a higher rate of postoperative infection than first time implants. We characterized biofilm formation on penile prostheses in clinically noninfected patients undergoing revision surgery.

Ten patients undergoing revision or removal of inflatable penile prosthetic devices due to mechanical malfunction were included. Specimens from the corporeal cylinders, scrotal pump and reservoir were analyzed. Bacterial biofilm coverage was detected and characterized using confocal scanning laser microscopy.

Bacterial biofilm formation associated with multiple microorganisms was demonstrated on 8 of 10 prostheses. Biofilms consisted of gram-positive rods, cocci and fungal elements.

The degree of biofilm formation on these prosthetic devices suggests that most patients have bacterial coverage on the implant. Host mechanisms to control infection may lead to a homeostatic balance that enables biofilms to exist on the surface of the prosthesis without generating clinical infection. A critical threshold of biofilm extent may exist beyond which clinical infection may occur. These results justify further evaluation of biofilms and penile prosthesis infections. Furthermore, the findings help to explain why strategies such as mini salvage procedures to eliminate subclinical biofilms may decrease the postoperative infection risk in patients undergoing repair or replacement of penile prostheses.