title: Staphylococcus aureus bacteremia after median sternotomy: clinical utility of blood culture results in the identification of postoperative mediastinitis.
abstract: BACKGROUND
  Mediastinitis is a complication of coronary artery bypass graft surgery (CABG) that can be difficult to diagnose. This study evaluated the utility of blood culture results in identifying patients with mediastinitis.
  
  
  RESULTS
  All unique patients undergoing CABG at our institution over a 60-month study period (n=5500) and all blood cultures performed on these patients <or=90 days after CABG were identified. Mediastinitis was identified by prospective active infection control surveillance. Eight hundred fifty-five (15.5%) patients had >or=1 blood culture drawn within 90 days of CABG. Mediastinitis occurred in 46 of 60 (76.7%) patients with blood cultures positive for Staphylococcus aureus, 15 of 126 (11.9%) patients with blood cultures positive for other pathogens, 37 of 669 (5.5%) patients with blood cultures with no growth, and 44 of 4645 (0.9%) patients with no blood cultures obtained. The isolation of S aureus from even 1 blood culture drawn after <or=90 days of CABG was strongly associated with mediastinitis (likelihood ratio [LR], 25; 95% CI, 14.7 to 44.4). Bacteremia attributable to other organisms did not alter pretest suspicion for mediastinitis (LR, 1.0; 95% CI, 0.6 to 1.7). Patients with negative blood cultures were less likely to have mediastinitis (LR, 0.45; 95% CI, 0.35 to 0.58). The association between S aureus bacteremia and mediastinitis remained highly significant when all unique patients undergoing CABG were analyzed in a logistic regression model and when a case-control analysis was used to evaluate patients with >or=1 blood culture obtained after CABG.
  
  
  CONCLUSIONS
  Among patients with blood cultures drawn after CABG, S aureus bacteremia strongly suggests the presence of mediastinitis.
authors.affiliation: Division of Infectious Diseases, Duke University Medical Center, Durham, NC 27710, USA. fowle003@mc.duke.edu
authors.forename: Vance G
authors.initials: VG
authors.lastname: Fowler
authors.forename: Keith S
authors.initials: KS
authors.lastname: Kaye
authors.forename: David L
authors.initials: DL
authors.lastname: Simel
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Cabell
authors.forename: Douglas
authors.initials: D
authors.lastname: McClachlan
authors.forename: Peter K
authors.initials: PK
authors.lastname: Smith
authors.forename: Scott
authors.initials: S
authors.lastname: Levin
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Sexton
authors.forename: L Barth
authors.initials: LB
authors.lastname: Reller
authors.forename: G Ralph
authors.initials: GR
authors.lastname: Corey
authors.forename: Eugene Z
authors.initials: EZ
authors.lastname: Oddone
mesh_terms: D000046:Academic Medical Centers; D000368:Aged; D016470:Bacteremia / Q000175:diagnosis / Q000382:microbiology*; D001431:Bacteriological Techniques; D016022:Case-Control Studies; D015331:Cohort Studies; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D003428:Cross Infection / Q000175:diagnosis / Q000382:microbiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017053:Infection Control; D016013:Likelihood Functions; D016015:Logistic Models; D008297:Male; D008480:Mediastinitis / Q000175:diagnosis / Q000382:microbiology*; D009657:North Carolina; D011183:Postoperative Complications / Q000175:diagnosis / Q000382:microbiology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018401:Sample Size; D013211:Staphylococcus aureus / Q000302:isolation & purification*; D013249:Sternum / Q000601:surgery*