DIAGNOSIS OF INFECTIVE ENDOCARDITIS: Due to the complexity of the clinical diagnosis of infective endocarditis, standardized diagnostic schemes have been developed to improve the sensitivity and specificity of the diagnosis. The Von Reyn criteria, introduced in 1981 relied mainly on clinical, microbiological, and histopathological criteria and were for more than 10 years regarded as the diagnostic goldstandard. However, the Von Reyn criteria have a sensitivity of merely about 30-60% and their reliability is especially low in case of negative blood cultures.
Role of echocardiography: An important step towards an improved sensitivity and specificity in the diagnosis of infective endocarditis was the introduction of transesophageal echocardiography, which is far more sensitive and specific in this indication than the transthoracic approach. Besides the early detection of vegetations and complications such as abscess formation, valvular destructions or perforations, echocardiography may be helpful to identify patients at risk for a prolonged healing, embolization, or may be also used to monitor the therapeutic progress.
The duke criteria: Implementation of echocardiography into the Duke criteria, introduced in 1994, yielded as expected, a significant higher sensitivity of up to 100% than the von Reyn criteria with an almost identical specificity. Thus, the latter were completely replaced by the Duke criteria in clinical practice.
Modifications of the duke criteria: Nevertheless, some uncertainty remains, especially in culture-negative endocarditis which has led to certain modifications of the Duke criteria. Besides the implementation of unspecific inflammatory parameters such as the C-reactive protein, a positive Q-fever serology has been added and any S. aureus bacteremia is now judged as major criterion. Although a prospective evaluation has to be awaited, these modifications appear promising and should be implemented into clinical practice.
Conclusions: The Duke criteria are currently the most sensitive tool in the diagnosis of infective endocarditis. It can be expected that they will help to significantly shorten the time to diagnosis, and may, thus, improve the clinical outcome.