For example, of 59 consecutive patients with S aureus IE, 45.8% had nosocomial infections, and 50.8% had a removable focus of infection.39 In an analysis of 262 patients at the Duke University Medical Center who had hospital-acquired S aureus bacteremia, 34 (13%) were subsequently diagnosed with definite IE. Therefore, the modi- fied Duke criteria (Tables 2 and 3) recommend the inclusion of S aureus bacteremia as a major criterion, regardless of whether the infection is hospital acquired (with or without a removable source of infection) or community acquired.24 Specific serological data have been included in the Duke IE diagnostic schema to establish the pathogenic agents of culture-negative IE more precisely (ie, as a surrogate for positive blood cultures). These serological criteria would be applied in circumstances in which the pathogenic organism is slow growing in routine blood cultures (eg, Brucella spe- cies) or requires special blood culture media (eg, Bartonella species, Legionella species, Tropheryma whipplei, fungi, and Mycobacterium species) or in which the organism is not culturable (eg, Coxiella burnetii, the agent of Q fever). For example, in the original Duke criteria, a positive serology for Q fever was considered a minor microbiological criterion. Subsequently, Fournier et al40 studied 20 pathologically con- firmed cases of Q fever IE. When the original Duke criteria were used, 4 of the 20 patients were classified as having pos- sible IE. When Q fever serological results and a single blood culture positive for C burnetii were considered to be a major criterion, however, each of these 4 cases was reclassified from possible IE to definite IE. On the basis of these data, specific serological data as a surrogate marker for positive blood cul- tures have now been included in the Duke criteria. 