title: Relationship between intraoperative cultures during hip arthroplasty, obesity, and the risk of early prosthetic joint infection: a prospective study of 428 patients.
abstract: OBJECTIVE
  To evaluate the relationship between intraoperative cultures during hip arthroplasty, the different patient characteristics, and the risk of developing a prosthetic joint infection (PJI).
  
  
  METHODS
  A prospective observational study was performed. Patients who underwent elective THA from March 2007 to March of 2011 were included. Three samples were taken just after arthrotomy: synovial fluid inoculated into blood culture flasks (SF), a tissue sample (TS), and a swab of peri- prosthetic tissue (S). Patients received standard antibiotic prophylaxis. The PJI rate within the first 3 months after arthroplasty was recorded.
  
  
  RESULTS
  402 prostheses were included in the study. Contamination rate of synovial fluid was 10.2%. The most frequent isolated microorganism was coagulase-negative staphylococci (CoNS) (32 out of 41). Body mass index (BMI) was the only host characteristic associated with positive intraoperative culture (p=0.009). The PJI rate was 3.7%. Variables associated with PJI in the univariate and multivariate analysis were: age =67 years (p=0.012 OR: 5.35 (1.45-19.81); CI95%) and a BMI =35 (p=0.002, OR: 7.7 (2.12-27.85) CI95%). PJI rate among patients with BMI<35 with negative and positive intraoperative cultures was 3% and 2.7%, respectively, however, the rate among patients with BMI = 35 was 15% and 25%, respectively.
  
  
  CONCLUSIONS
  A BMI =35 was associated with a higher risk of positive intraoperative culture during hip arthroplasty. In addition, a BMI ≥35 was independently associated with a high risk of PJI and the highest rate was documented among obese patients with positive intraoperative cultures.
authors.affiliation: Department of Orthopedics and Trauma Surgery, Parc Sanitari Sant Joan de Dèu, Sant Boi de Llobregat, Barcelona, Spain. drfontvizcarra@gmail.com
authors.forename: Lluís
authors.initials: L
authors.lastname: Font-Vizcarra
authors.forename: Eduard
authors.initials: E
authors.lastname: Tornero
authors.forename: Guillem
authors.initials: G
authors.lastname: Bori
authors.forename: Jordi
authors.initials: J
authors.lastname: Bosch
authors.forename: Josep
authors.initials: J
authors.lastname: Mensa
authors.forename: Alex
authors.initials: A
authors.lastname: Soriano
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation; D015992:Body Mass Index; D016009:Chi-Square Distribution; D017558:Elective Surgical Procedures; D005260:Female; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D016017:Odds Ratio; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000175:diagnosis / Q000209:etiology* / Q000382:microbiology / Q000628:therapy; D018570:Risk Assessment; D012307:Risk Factors; D013030:Spain; D013582:Synovial Fluid / Q000382:microbiology; D013997:Time Factors; D016896:Treatment Outcome