title: Gram-negative prosthetic joint infections: risk factors and outcome of treatment.
abstract: BACKGROUND
  Little information is available regarding the demographic characteristics and outcomes of patients with prosthetic joint infection (PJI) resulting from gram-negative (GN) organisms, compared with patients with PJI resulting from gram-positive (GP) organisms.
  
  
  METHODS
  We performed a retrospective cohort analysis of all cases of PJI that were treated at our institution during the period from 2000 through 2006.
  
  
  RESULTS
  GN microorganisms were involved in 53 (15%) of 346 first-time episodes of PJI, and Pseudomonas aeruginosa was the most commonly isolated pathogen (21 [40%] of the 53 episodes). Patients with GN PJI were older (median age, 68 vs. 59 years; P<.001) and developed infection earlier (median joint age, 74 vs. 109 days; P<.001) than those with GP PJI. Of the 53 episodes of GN PJI, 27 (51%) were treated with debridement, 16 (30%) with 2-stage exchange arthroplasty, and 10 (19%) with resection arthroplasty. Treating GN PJI with debridement was associated with a lower 2-year cumulative probability of success than treating GP PJI with debridement (27% vs. 47% of episodes were successfully treated; P=.002); no difference was found when a PJI was treated with 2-stage exchange or resection arthroplasty. A longer duration of symptoms before treatment with debridement was associated with treatment failure for GN PJI, compared with for GP PJI (median duration of symptoms, 11 vs. 5 days; P=.02).
  
  
  CONCLUSIONS
  GN PJI represents a substantial proportion of all occurrences of PJI. Debridement alone has a high failure rate and should not be attempted when the duration of symptoms is long. Resection of the prosthesis, with or without subsequent reimplantation, as a result of GN PJI is associated with a favorable outcome rate that is comparable to that associated with PJI due to GP pathogens.
authors.affiliation: Department of Orthopedic Surgery, Chang Gung Memorial Hospital, No. 5, Fu-Hsing St., 333 Kweishian, Taoyuan, Taiwan. hsiehph@adm.cgmh.org.tw
authors.forename: Pang-Hsin
authors.initials: PH
authors.lastname: Hsieh
authors.forename: Mel S
authors.initials: MS
authors.lastname: Lee
authors.forename: Kuo-Yao
authors.initials: KY
authors.lastname: Hsu
authors.forename: Yu-Han
authors.initials: YH
authors.lastname: Chang
authors.forename: Hsin-Nung
authors.initials: HN
authors.lastname: Shih
authors.forename: Steve W
authors.initials: SW
authors.lastname: Ueng
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement / Q000009:adverse effects*; D015331:Cohort Studies; D003646:Debridement; D005260:Female; D006090:Gram-Negative Bacteria / Q000145:classification / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology / Q000628:therapy*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016459:Prosthesis-Related Infections / Q000453:epidemiology* / Q000382:microbiology / Q000628:therapy*; D012092:Replantation; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome