Abstract
Objectives - To develop and validate a prediction score, to quantify, within 48 h of Staphylococcus aureus bacteremia (SAB) diagnosis, the risk of IE, and therefore determine priority for urgent echocardiography. Methods - Consecutive adult patients with SAB in 8 French university hospitals between 2009 and 2011 were prospectively enrolled and followed-up 3 months. A predictive model was developed and internally validated using bootstrap procedures. Results - Among the 2008 patients enrolled, 221 (11.0%) had definite IE of whom 39 (17.6%) underwent valve surgery, 25% of them within 6 days of SAB diagnosis. Ten predictors independently associated with IE were used to build up the prediction score: intracardiac device or previous IE, native valve disease, intravenous drug use, community or non-nosocomial-acquisition, cerebral or extracerebral emboli, vertebral osteomyelitis, severe sepsis, meningitis, C-reactive protein above 190 mg/L, and H48-persistent bacteremia. Patients with a score ≤2 (n = 792, 39.4%) were at low IE-risk (1.1%; negative predictive value: 98.8% (95% CI, 98.4-99.4)) compared to those ≥3 who were at higher risk (17.4%). Conclusions - Physicians must be strongly encouraged to urgently perform echocardiography in SAB patients with a score ≥3 to establish IE diagnosis, to orient antimicrobial therapy and to help determine the need for valvular surgery.