Author(s): Javad Parvizi*, Elie Ghanem, Jill Steinbrecher, Noreen Hickok, Robert L. Barrack; Rothman Institute,Philadelphia, PA
Title: The Changing Organism Profile in Periprosthetic Infection
Purpose: Periprosthetic infection (PPI) continues to compromise the outcome of otherwise successful joint replacement. The objective of this study was to evaluate the profile of organisms that have caused PPI over the last few years.
Methods: All 351 patients with PPI who received surgical treatment at our institution during 1999 to 2005 were included. The surgical treatment involved irrigation and debridement in 97 cases (28%), one-stage exchange arthroplasty in 31 cases (9%) and two-stage exchange arthroplasty in 217 cases (62%). The remaining 5 cases (1%) included patients who underwent revision arthroplasty for mechanical reasons but had multiple positive intraoperative cultures that necessitated antibiotic treatment. Patients were included only once in the analysis unless an organism was grown during a second revision procedure that was different from the one cultured during the initial surgery.
Results: The burden of PPI at our institution has increased over the last few years. Gram positive cocci cause 92% of PPI, while the incidence of infection with gram negative organisms (8%) was relatively low. A steady increase in the incidence of infections caused by methicillin resistant staphylococcus was noted with the incidence increasing from 13% in 1999 to over twice that at 30% in 2005.
Discussion: Our data indicates that a change in the profile of infecting organisms resulting in PPI has occurred over the last few years, at least at our institution. The increase in the number of infections caused by methicillin resistant organisms could potentially compromise the success of current treatment for this problem. Although liberal use of antibiotic is likely to be the major reason, future studies are needed to assess the reason behind the worrisome rise in the incidence of methicillin resistant periprosthetic infections.