Prosthetic Device Infections

Abstract

Fortunately, infection is a rare complication of prosthetic devices. Despite the presence of infection, removal of these devices is not always possible or necessary. The introduction of foreign material enhances the pathogenicity of known pathogens and increases the potential of less virulent microorganisms to cause damage. Thus, Staphylococcus epidermidis is a very common organism in patients with prosthetic devices as compared with the normal healthy population. Fibronectin promotes adherence of staphylococci to chronically implanted devices. An extracellular substance called “glycocalyx” has been associated with coagulase-negative staphylococci including S. epidermidis. A polysaccharide “adhesin” facilitates adherence of staphylococci to foreign material and functions as an antiphagocytic capsule. The function of polymorphonuclear leukocytes is also impaired in the presence of foreign bodies. There is deficient superoxide production, which leads to impaired killing of microorganisms. Also, recent data suggest a role for small colony variants (SCV) of staphylococci that may cause persistent and recurrent infections as a result of their capacity to survive within, but not lyse, whole cells. When these bacteria adhere to foreign bodies, they undergo dramatic metabolic changes such as slower growth, decreased metabolism, and enhanced resistance to antibiotics. These organisms can be difficult to detect in the microbiology laboratory and also difficult to treat with conventional antibiotics (1).