title: Multiplex PCR of sonication fluid accurately differentiates between prosthetic joint infection and aseptic failure.
abstract: OBJECTIVE
  Cultures have limited sensitivity in the diagnosis of prosthetic joint infection (PJI), especially in low-grade infections. We assessed the value of multiplex PCR in differentiating PJI from aseptic failure (AF).
  
  
  METHODS
  Included were patients in whom the joint prosthesis was removed and submitted for sonication. The resulting sonication fluid was cultured and investigated by multiplex PCR, and compared with periprosthetic tissue culture.
  
  
  RESULTS
  Among 86 explanted prostheses (56 knee, 25 hip, 3 elbow and 2 shoulder prostheses), AF was diagnosed in 62 cases (72%) and PJI in 24 cases (28%). PJI was more common detected by multiplex PCR (n=23, 96%) than by periprosthetic tissue (n=17, 71%, p=0.031) or sonication fluid culture (n=16, 67%, p=0.016). Among 12 patients with PJI who previously received antibiotics, periprosthetic tissue cultures were positive in 8 cases (67%), sonication fluid cultures in 6 cases (50%) and multiplex PCR in 11 cases (92%). In AF cases, periprosthetic tissue grew organisms in 11% and sonication fluid in 10%, whereas multiplex PCR detected no organisms.
  
  
  CONCLUSIONS
  Multiplex PCR of sonication fluid demonstrated high sensitivity (96%) and specificity (100%) for diagnosing PJI, providing good discriminative power towards AF, especially in patients previously receiving antibiotics.
authors.affiliation: Microbiology Laboratory, Reference Laboratory of Catalunya, Carrer de la Selva, 10, Edifici Inblau A. Parc de Negocis MasBlau I, El Prat de Llobregat, 08820 Barcelona, Spain. eportillo@lrc.es
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Portillo
authors.forename: Margarita
authors.initials: M
authors.lastname: Salvadó
authors.forename: Lluisa
authors.initials: L
authors.lastname: Sorli
authors.forename: Albert
authors.initials: A
authors.lastname: Alier
authors.forename: Santos
authors.initials: S
authors.lastname: Martínez
authors.forename: Andrej
authors.initials: A
authors.lastname: Trampuz
authors.forename: Julià
authors.initials: J
authors.lastname: Gómez
authors.forename: Lluis
authors.initials: L
authors.lastname: Puig
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Horcajada
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification; D001424:Bacterial Infections / Q000175:diagnosis* / Q000382:microbiology; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D007595:Joint Prosthesis / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods*; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000175:diagnosis* / Q000382:microbiology; D012680:Sensitivity and Specificity; D013010:Sonication