title: Etiology of bone and joint infections: a case series of 363 consecutive patients from an orthopaedic infection unit.
abstract: BACKGROUND
  Bone and joint infections remain a clinical challenge with potentially serious consequences. Nevertheless there is a lack of studies with strict criteria for diagnosis and etiology. The primary aim of this study was to determine the causative agents in orthopaedic infections using strict diagnostic criteria for infection and etiology. The secondary aim was to assess the timing of post-operative infections in relation to pathogens and to compare causative bacteria in different parts of the body.
  
  
  METHODS
  A retrospective registry study of 363 consecutive cases of bone and joint infections was performed. Microbiological data on sampling and culture results were registered.
  
  
  RESULTS
  Staphylococcus aureus dominated in both operated (45%) and non-operated (44%) patients, followed in frequency by coagulase-negative staphylococci (CoNS) in operated patients (11%) and beta-haemolytic streptococci in non-operated patients (16%) (p < 0.001). There were no polymicrobial infections in non-surgical cases (p < 0.001). For operated patients, Gram-negative bacilli were observed in 6%, almost exclusively isolated from the lower extremity. Propionibacterium spp. was the most common finding after spinal surgery. In 90/363 (25%), the agent responsible for the infection could not be defined according to the strict criteria used.
  
  
  CONCLUSIONS
  S. aureus dominated as etiological agent in all bone and joint infections, including operated patient given peri-operative prophylaxis. Improved timing of antibiotic prophylaxis seen after the introduction of the Swedish national project PRISS may have changed this. The number of infections with uncertain etiology was high, stressing the importance of more studies on diagnostics, as well as strict diagnostic algorithms.
authors.affiliation: a Department of Infectious Diseases , Karolinska Institutet, Karolinska University Hospital , Stockholm , Sweden ;
authors.forename: Katja
authors.initials: K
authors.lastname: Wallander
authors.affiliation: b Department of Clinical Science and Education , Stockholm South General Hospital, Karolinska Institutet , Stockholm , Sweden ;
authors.forename: Christina
authors.initials: C
authors.lastname: Jorup-Rönström
authors.affiliation: c Department of Clinical Microbiology , Karolinska University Hospital , Stockholm , Sweden ;
authors.forename: Måns
authors.initials: M
authors.lastname: Ullberg
authors.affiliation: c Department of Clinical Microbiology , Karolinska University Hospital , Stockholm , Sweden ;
authors.forename: Inger
authors.initials: I
authors.lastname: Törnblom
authors.affiliation: b Department of Clinical Science and Education , Stockholm South General Hospital, Karolinska Institutet , Stockholm , Sweden ;
authors.forename: Carin
authors.initials: C
authors.lastname: Ottosson
authors.affiliation: c Department of Clinical Microbiology , Karolinska University Hospital , Stockholm , Sweden ;|d Division of Clinical Microbiology, Department of Laboratory Medicine , Karolinska Institutet Stockholm , Sweden.
authors.forename: Christian G
authors.initials: CG
authors.lastname: Giske
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001850:Bone Diseases, Infectious / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D006760:Hospitalization; D006801:Humans; D007592:Joint Diseases / Q000453:epidemiology* / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
keywords: Bone and joint infection; Propionibacterium spp; Staphylococcus aureus; etiology; perioperative prophylaxis