Device-related infections: a review

Abstract

The use of surgically implanted devices has increased as a result of their beneficial effect on quality of life, and in some circumstances, on patient survival rates. They can, however, be associated with a variety of complications, the most dreaded being infection. Device-related infections are important to understand because of the morbidity and mortality associated with them. Frequently, patients are managed with hospitalization, prolonged courses of antibiotics, and surgical interventions, all of which can negatively impact on patients' quality of life. Such care is also associated with increased costs to health care systems. Furthermore, these infections often represent a diagnostic challenge because of the lack of consensus definition of what constitutes an infection and its severity, as well as the paucity of well-designed, large studies addressing optimal methods of investigation and management. An implant-associated infection is defined as a host immune response to one or more microbial pathogens on an indwelling implant. An understanding of the pathogenesis of these infections provides a rationale for management. Development of device-related infections begins with colonization of the foreign material, followed by a complex metamorphosis by the microorganisms with resultant biofilm formation. In this surface-associated form, bacteria have altered phenotypic properties. This change, in conjunction with the physical protective layer provided by the biofilm, renders antimicrobial therapy ineffective when used alone. Because the microorganisms are able to reside on the hardware, they proliferate and cause local damage, such as loosening of implanted devices, wound dehiscence, or disruption of prosthetic valves, as well as systemic manifestations, such as fever or embolic phenomenon. The onset and clinical manifestations of device-related infections vary with the pathogen involved, as well as which component of the device is affected. The time period after device implantation that signs and symptoms develop can assist in the selection of empiric antimicrobial therapy. Optimal diagnostic microbiologic specimens are paramount in tailoring the antimicrobial therapy, which almost always has to be given for a prolonged period of time. Surgical removal of the device is usually necessary. Some studies of limited types of device-related infections, however, have defined indications for which salvage therapy may be warranted. In addition, some patients are not candidates for, or may not want, further surgical interventions, in which case indefinite suppressive antimicrobial therapy may be considered. This review provides an overview of infections related to various neurosurgical, cardiac, and orthopedic devices, as well as those related to cochlear, breast, and penile prostheses, with discussion of definitions of such infections, along with microbiology, pathogenesis, and management guidelines, including the limited indications for salvage techniques.