title: Use of real-time polymerase chain reaction for the diagnosis of infection and differentiation between gram-positive and gram-negative septic arthritis in children.
abstract: BACKGROUND
  Diagnosis and identification of the etiological agent of septic arthritis (SA) in children is an important issue, as early treatment based on accurate diagnosis of joint infections can prevent potentially disabling complications. The purpose of this study was to evaluate the efficacy of real-time polymerase chain reaction (PCR) for the diagnosis of SA in children.
  
  
  METHODS
  Twenty children with suspected SA who had joint pain and underwent surgical treatment were enrolled in this study. Their preoperative clinical and laboratory findings were investigated. Tissues obtained during operation were subjected to microbiological culture and real-time PCR, including methicillin-resistant Staphylococcus (MRS)-specific PCR and broad range universal PCR. Infection was confirmed if the result of microbiological culture was positive. Furthermore, abnormal clinical and laboratory findings and improvement in the symptoms and posttreatment data were also defined as the final diagnosis of infection.
  
  
  RESULTS
  Out of the 20 patients, 19 were diagnosed with the infection. The remaining patient was postoperatively diagnosed with juvenile idiopathic arthritis. Abnormal preoperative body temperatures, white blood cell counts, C-reactive protein levels, and erythrocyte sedimentation rates were observed in 6, 9, 15, and 12 cases, respectively. The results of microbiological culture, MRS-PCR, and universal PCR were positive in 9, 2, and 15 cases, respectively. Analysis of the melting peak in universal PCR revealed that of the 15 cases, 10 had gram-positive and 5 had gram-negative infections. The sensitivity and specificity for the diagnosis of SA were, respectively, 0.47 and 1.00 in microbiological culture and 0.79 and 1.00 in real-time PCR.
  
  
  CONCLUSIONS
  Successful diagnosis of infection and differentiation between gram-positive and gram-negative bacteria were achieved using MRS-PCR and universal PCR. Hence, real-time PCR is useful and has greater sensitivity than microbial culture for diagnosing SA in children.
  
  
  METHODS
  Level II diagnostic study investigating a diagnostic test.
authors.affiliation: Department of Orthopaedic Surgery, Yokohama City University School of Medicine, Yokohama, Japan.
authors.forename: Hyonmin
authors.initials: H
authors.lastname: Choe
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Inaba
authors.forename: Naomi
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Chie
authors.initials: C
authors.lastname: Aoki
authors.forename: Jiro
authors.initials: J
authors.lastname: Machida
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Nakamura
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Okuzumi
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Saito
mesh_terms: D000293:Adolescent; D001170:Arthritis, Infectious / Q000175:diagnosis* / Q000382:microbiology*; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000175:diagnosis*; D016908:Gram-Positive Bacterial Infections / Q000175:diagnosis*; D006801:Humans; D007223:Infant; D008297:Male; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction