Excerpt

Clinically managing acute endocarditis, an infection of the heart valves with a mortality rate of up to 47%, remains highly challenging and frequently unsuccessful.1,2 The most common pathogen behind acute endocarditis is Staphylococcus aureus, followed by Streptococcus species.2,3 Unmet clinical needs in treating acute endocarditis include: (i) more reliably diagnosing or excluding endocarditis, (ii) quickly and precisely identifying the pathogen dwelling in vegetations informing selection of antibiotics, and (iii) acquiring more quantitative data to guide decisions about surgical intervention. Currently, clinically diagnosing endocarditis relies on the modified Duke criteria,4 which combine major and minor criteria including echocardiographic imaging, clinical signs such as a new heart murmur or fever, and detection of circulating bacteria in blood cultures. Unfortunately, blood cultures can be misleading; false-negative results occur when the pathogen is present in the vegetation but not in circulation at the time of blood withdrawal, as can occur, for instance, after initiation of antibiotic therapy. The following case report from the Massachusetts General Hospital clinical service highlights this typical problem. …