Anti-infective catheters: A difficult search for effective slow delivery systems

Nosocomial infection are estimated to involve more than 2 million patients annually and in 1992 cost more than $4,5 billion in the USA (1). The surfaces of indwelling medical devices are an excellent platform for th e formation of life-threatening infections. Although aseptic techniques can reduce the incidence of these infections, a significant risk remains. The coupling or incorporation of antimicrobial substances to or into catheter m aterials may be a suitable way to prevent the development of catheter assoc iated infections as suggested by in vitro and in vivo studies. Various surf ace treatments are emerging as important. Early efforts that concentrated o n adsorption of antibiotics to device surfaces achieved limited results as shown in several clinical studies. The promising approach features the inco rporation of antimicrobial drugs into the polymer matrices that entrap but do not bind the drugs, allowing for extended release. Incorporation of anti microbials in the bulk material that constitutes a device can be effective as shown in several in vitro and in vivo studies. In future, modification o f both short-term and long term catheters by biofilm-active antimicrobials creating slow delivery systems may provide an effective method to protect p atients from nosocomial infection.