Long-term prosthetic devices are rapidly recovered by host proteins which increase bacterial adhesion. The bacteria can also produce extracellular polysaccharide material, which in combination of host proteins, produce a biofilm. This one decreases the host defense mechanisms, antibiotics penetration and efficacy, increasing infectivity of the pathogens. Most often, the device is contaminated in the perioperative period by commensal flora. It can also be infected by hematogenous seeding or by contiguous infection. Various clinical presentations of infected devices are described depending on the type of prosthesis, its anatomical localisation and the time elapsed since insertion. Postoperative acute sepsis, insidious infectious signs or isolated device malfunction without signs of infection have all been described. The prosthetic infection rate is low, but when it occurs, the consequences are catastrophic. Excepted in some selected cases, the classical treatment combines the removal of the prosthesis and a long-term appropriate antibiotic therapy. If infection is suspected, it's crucial to establish the diagnosis accurately often by using invasive diagnostic methods (CT-scan guided biopsy, etc.) to obtain adequate samples which detailed microbiological analysis should be carefully interpreted.