title: Prosthetic knee infection by resistant bacteria: the worst-case scenario.
abstract: OBJECTIVE
  The aim of the present paper was to determine (1) the incidence of failure (defined as the persistence or the recurrence of the infection), (2) the incidence of prosthesis (or even limb) loss (defined as the final need for an arthrodesis, resection arthroplasty or amputation) and (3) what factors could influence the failure in patients treated with a two-stage reimplantation for periprosthetic knee infections caused by resistant bacteria.
  
  
  METHODS
  The authors retrospectively reviewed 29 total knee arthroplasties infected by resistant bacteria in 29 patients who underwent a two-stage revision. Between the stages, intravenous-targeted antibiotics were administered for a median period of 8 (range 6-12) weeks. Median follow-up was 10 (range 7-14) years.
  
  
  RESULTS
  The authors found that failure occurred in 5 of 29 patients (17.2 %). When methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative staphylococci (MR-CoNS) were involved, failure rate was 10 % (2 of 20). When vancomycin-resistant enterococcus (VRE), multidrug-resistant (MDR) Acinetobacter baumannii and MDR Pseudomonas aeruginosa were involved, the failure rate was 33.3 % (3 of 9). Of those five patients, two underwent amputations, one chronic suppressive antibiotic therapy, one arthrodesis and one resection arthroplasty; among them, three lost the limb (10.3 % of the overall group). Timing of reimplantation and patient comorbidities did not significantly influence the failure.
  
  
  CONCLUSIONS
  Two-stage protocol resulted in a viable option for patients with infections by some resistant organisms (MRSA and MR-CoNS). However, when highly resistant organisms were involved (VRE, MDR Acinetobacter Baumannii and MDR Pseudomonas aeruginosa), the failure rate was much higher. In all cases of failure of the two-stage reimplantation, prosthesis (or even limb) loss occurred. Consequently, patients should be counselled that when highly resistant bacteria are involved, two-stage reimplantation could not be successful, with high final risk of prosthesis (or even limb) loss.
  
  
  METHODS
  Retrospective case series, Level IV.
authors.affiliation: Department of Medicine and Health Sciences, University of Molise, Via Francesco De Sanctis, 86100, Campobasso, Italy. vassomichele@gmail.com.
authors.forename: Michele
authors.initials: M
authors.lastname: Vasso
authors.affiliation: Department of Medicine and Health Sciences, University of Molise, Via Francesco De Sanctis, 86100, Campobasso, Italy.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Schiavone Panni
authors.affiliation: Adult Reconstruction and Joint Replacement Division, Department of Orthopaedic Surgery, Hospital for Special Surgery, 535 East 70th Street, New York, NY, 10021, USA.
authors.forename: Ivan
authors.initials: I
authors.lastname: De Martino
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Magna Graecia University, Mater Domini University Hospital, Viale Europa, 88100, Catanzaro, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Gasparini
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000671:Amputation, Surgical; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001174:Arthrodesis; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D016459:Prosthesis-Related Infections / Q000382:microbiology* / Q000628:therapy; D012086:Reoperation / Q000379:methods; D012189:Retrospective Studies
chemical_list: D000900:Anti-Bacterial Agents
keywords: Failure; Infection; Resistant bacteria; Total knee arthroplasty; Total knee replacement; Two-stage reimplantation
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