title: Does intraoperative tissue sample enrichment help or hinder the identification of microorganisms in prosthetic joint infection?
abstract: OBJECTIVE
  Biofilm formation reduces the efficacy of standard microbiological techniques in prosthetic joint infection. This study aimed to investigate the sensitivity, specificity and predictive values of tissue sample enrichment as a means to increase diagnostic yield.
  
  
  METHODS
  Patients undergoing revision arthroplasty surgery between May 2004 and January 2013 had intraoperative tissue samples cultured in standard media as well as enriched in brain heart infusion broth. Patients were separated into infected or non-infected groups according to modified criteria from the Musculoskeletal Infection Society.
  
  
  RESULTS
  A total of 197 revision arthroplasties were included (non-infected, n = 165; proven infection, n = 32). The mean time until revision in non-infected and infected groups was 75.9 and 41.7 months, respectively. The commonest microorganisms cultured were coagulase-negative staphylococci (42.9 %) and Staphylococcus aureus (34.4 %). The sensitivity and specificity of standard tissue culture were 0.25 (CI 0.18-0.33) and 0.98 (CI 0.95-0.99), respectively. Including enrichment culture results increased the sensitivity to 0.45 (CI 0.37-0.54), but decreased specificity to 0.59 (CI 0.52-0.66).
  
  
  CONCLUSIONS
  Any potential increase in the sensitivity is far outweighed by the extremely high false-positive rate. Results of tissue samples cultured by enrichment should be used with caution and may lead to a worse outcome if incorrectly interpreted.
authors.affiliation: University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Walsgrave, Coventry, CV2 2DX, UK.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Jordan
authors.forename: Adnan
authors.initials: A
authors.lastname: Saithna
authors.forename: Nicholas
authors.initials: N
authors.lastname: Smith
authors.forename: Rory
authors.initials: R
authors.lastname: Norris
authors.forename: Andrew
authors.initials: A
authors.lastname: Sprowson
authors.forename: Pedro
authors.initials: P
authors.lastname: Foguet
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D001178:Arthroplasty / Q000379:methods*; D018441:Biofilms; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007430:Intraoperative Care / Q000379:methods; D008297:Male; D008875:Middle Aged; D016459:Prosthesis-Related Infections / Q000175:diagnosis / Q000382:microbiology*; D012086:Reoperation; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods*; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000382:microbiology*; D013210:Staphylococcus / Q000302:isolation & purification*; D013211:Staphylococcus aureus; D055815:Young Adult