title: Characteristics and outcome of 16 periprosthetic shoulder joint infections.
abstract: OBJECTIVE
  Shoulder arthroplasties are increasingly performed, but data on periprosthetic joint infections (PJI) in this anatomical position are limited. We retrospectively investigated the characteristics and outcome of shoulder PJI after primary arthroplasty from 1998 to 2010 in a single centre.
  
  
  METHODS
  Periprosthetic joint infection was defined as periprosthetic purulence, presence of sinus tract or microbial growth. A Kaplan-Meier survival method was used to estimate relapse-free survival of prosthesis.
  
  
  RESULTS
  From 1,571 primary shoulder prostheses, we evaluated 16 patients with a PJI at different stages, i.e, early (n = 4), delayed (n = 6) and late (n = 6) infections. The median patient age was 67 (range 53-86) years, and 69 % were females. The most commonly isolated microorganism was Propionibacterium acnes in 38 % of patients (monobacterial in four and polymicrobial in two patients). In 14 of the 16 patients, surgical interventions consisting of debridement and implant retention (6 patients), exchange (7) and explantation (1) were performed. Four patients had a relapse of infection with P. acnes (n = 3) or Bacteroides fragilis (n = 1). The relapse-free survival of the prosthesis was 75 % (95 % confidence interval 46-90 %) after 1 and 2 years, 100 % in six patients following the treatment algorithm for hip and knee PJI and 60 % in 10 patients not followed up. All but one of the relapses were previously treated without exchange of the prosthesis.
  
  
  CONCLUSIONS
  As recommended for hip and knee PJI, we suggest treating shoulder PJI with a low-grade infection by microorganisms such as P. acnes with an exchange of the prosthesis. Cohort studies are needed to verify our results.
authors.affiliation: Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland. yvonne.achermann@gmail.com
authors.forename: Y
authors.initials: Y
authors.lastname: Achermann
authors.forename: F
authors.initials: F
authors.lastname: Sahin
authors.forename: H K
authors.initials: HK
authors.lastname: Schwyzer
authors.forename: C
authors.initials: C
authors.lastname: Kolling
authors.forename: J
authors.initials: J
authors.lastname: Wüst
authors.forename: M
authors.initials: M
authors.lastname: Vogt
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001178:Arthroplasty / Q000009:adverse effects / Q000379:methods; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification*; D001442:Bacteroides Infections; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology*; D016459:Prosthesis-Related Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology*; D012189:Retrospective Studies; D012785:Shoulder Joint / Q000382:microbiology / Q000473:pathology*; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents