Microbiology of the infected total joint arthroplasty.

Infection associated with arthroplasty is a relatively rare event, but when it does occur, it is of major consequence for the patient. Many organisms can cause these infections, but most are the results of gram-positive bacteria, with the genus Staphylococcus accounting for at least 50%. Streptococcus and aerobic gram-negative bacilli are responsible for another significant percentage. The ability of the organism to produce a slime or glycocalix extracellular layer seems to be a contributing virulence factor for prosthesis-associated infections. Growth, identification, and susceptibility testing of the etiologic agent are performed by the microbiology laboratory, but antimicrobial treatment is usually only successful after removal of the prosthesis.