Why focus of implant infections

Infections remain the Achilles heel of surgical implantation of medical devices and artificial organs. Although the overall incidence of implant infections and their complications can be reduced by the development of new infection-resistant materials and new antimicrobial strategies, the health and social costs of these infections are still high. Two million cases pf nosocomial infections annually occur in the United States alone. The presence of an indwelling medical device has been found to account for approximately 45% of all nosocomial infections. The infection rate for orthopaedic replacements alone is approaching 2.5%, yelding 25,000 cases of orthopaedic implant failure per year. Implant infections can give rise to osteomyelitis, often necessitating amputation or extremely wide excision with complex reconstructive surgery. This issue of IJAO is devoted to a focus on implant associated infections, from different points of view from aetiology and pathogenesis, to prevention and therapy. Advances in bioengineering have produced an exceptional growth in the use of indwelling medical devices, from “simple”, such as catheters and stents, to “complex”, such as implantable cardiodefibrillators and left ventricular assist devices. Many microorganisms are able to adhere to implant surfaces and colonize on them, where they can form biofilms that often lead to persistent infections. The ability to form biofilms is considered a virulence factor for several pathogens, i.e. staphylococci, Candida and enterococci. The present issue just focus on adhesion mechanisms of bacteria to implant surface and devotes large attention to the role of biofilm in the early stage of infection. Besides biofilm, bacterial MSCRAMMs (Microbial Surface Components Recognizing Adhesive Matrix Molecules) are a variform family of bacterial cell surface protein adhesins, that recognize and bind specific extracellular matrix components such as fibrinogen, collagen, and fibronectin within host tissues. Binding of MSCRAMMs to distinct matrix proteins facilitates bacterial attachment, thereby allowing colonization and invasion of the host tissues. Micro-organisms that cause device-related infections expressing MSCRAMMs proteins most notably are staphylococci, streptococci, enterococci, and Candida albicans. The increasing knowledge on the mechanisms of bacterial adhesion to indwelling medical devices necessarily brings to new concepts and new strategies for therapy. Innovative approaches are derived from nanotechnology such as nanocapsules loaded with an active drug. These particles should be small enough to pass through the capillary system, should consist of non-toxic and biodegradable material and must combine suitable release and targeting properties. A special therapeutic application of nanocapsules may be in connection with implant infections, especially if the infection is connected to the presence of a biofilm. A different, also innovative approach is to point to a staphylococcal vaccine. Many studies have the target to assess whether vaccination with MSCRAMM proteins or protein fragments have a capacity to protect against staphylococcal infection. The possibility of antibodies synergizing with antibiotics or, in the future, treatments that inhibit the transcription of biofilm controlling genes, could extend the therapeutic options available to the clinician, reduce the duration of therapy, and significantly impact health-care costs.