Subjects will be consented and then determined randomly whether they will receive antibiotics prior to their surgery or during their surgery. Each patient will have cultures taken before and during their surgery from the infected hip or knee. Results will be compared after completion of the study.

It is unknown whether giving pre-operative antibiotics affects the results of intraoperative bacterial cultures. This is an important question as antibiotics are often not given prior to surgery out of concern that accurate culture results will not be obtained. It is important to obtain accurate cultures so that targeted antibiotic therapy can be used. However, delaying the administration of antibiotics also delays the onset of treatment. Currently, the optimal course of action is unknown. The purpose of this study is to resolve this issue and determine if prophylactic antibiotics affect intra-operative culture results in patients undergoing revision hip or knee arthroplasty surgery for infection.

This is a prospective randomized clinical study to determine if prophylactic antibiotics affect intra-operative culture results in patients undergoing revision hip or knee arthroplasty surgery for infection. Pre-operatively, patients will have their affected joint aspirated and this fluid will be sent for cultures. Patients are then randomized to receive prophylactic antibiotics (Vancomycin and Ancef) within one hour prior to surgery or to have pre-operative antibiotics withheld. Every patient then has their affected joint cultured intra-operatively. All samples will be evaluated for the presence of aerobic bacteria, anaerobic bacteria, mycobacteria, and fungus. Pre-operative and post-operative cultures in both study populations are compared to determine the effects of pre-operative antibiotics.

Inclusion Criteria:

• prior arthroplasty surgery of the hip or knee
• presentation to clinic with infected joint
• scheduled for revision surgery

Exclusion Criteria:

• patients who have received antibiotics for any reason within 4 weeks of their pre-operative culture
• infected native joints
• septic patients
• refusal of participation