Prophylactic antibiotics do not affect cultures in the treatment of an infected TKA: a prospective trial

Abstract

Prophylactic antibiotics are frequently withheld until cultures are obtained in revision total knee arthroplasty (TKA). We undertook a prospective study to determine whether prophylactic preoperative intravenous antibiotics would affect the results of cultures obtained intraoperatively. We enrolled 25 patients with 26 infected TKAs, a known preoperative infecting organism, and no recent antibiotic therapy. Reaspiration of the infected TKA was performed after anesthesia and sterile preparation. Intravenous antibiotic prophylaxis was then administered and the tourniquet inflated. Intraoperative culture swabs and tissue were obtained at arthrotomy. The timing of events was recorded. Pre- and postantibiotic culture data were analyzed to determine the effect of intravenous preoperative prophylactic antibiotics on cultures obtained intraoperatively. Infections were acute postoperative (four), chronic (19), and acute hematogenous (three). The most common infecting organism was cloxacillin-sensitive Staphylococcus aureus (nine knees [35%]). Preoperative prophylactic antibiotics did not affect the results of intraoperative cultures and we therefore believe should not be withheld before surgery for an infected TKA when an organism has been identified on aspiration preoperatively, and there has been no recent (4 weeks) antimicrobial therapy.

Level of evidence: Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Fig. 1A–E

A 66-year-old man presented with bilateral infected TKA at 20 weeks (chronic Type 3 infection) after primary TKAs. Preoperative and operative cultures both grew Staphylococcus aureus sensitive to cloxacillin despite administration of intraoperative antibiotics. (A) Preoperative anteroposterior (AP) radiographs of bilateral TKA suggest septic loosening of both tibial cementless components. (B) Preoperative lateral radiographs are shown. (C) Bilateral AP radiographs after explantation of femoral, tibial, and patellar irrigation and débridement of the infected TKAs are shown. A static antibiotic-loaded cement spacer has been inserted bilaterally. The patient was treated with 6 weeks of intravenous antibiotics. The erythrocyte sedimentation rate and C-reactive protein normalized, and both knees were reaspirated at 10 weeks with no growth of bacteria. (D) Bilateral second-stage reimplantation TKAs were performed at 12 weeks after the explant procedure as shown in AP radiographs. (E) Bilateral lateral postoperative radiographs are shown.