Epidemiology of bloodstream infections and infective endocarditis: new insights on typical species and echocardiography screening

Background Real-world data on bloodstream infections (BSI) and infective endocarditis (IE) epidemiology, their implications for screening and the applicability of typical species concepts by guidelines are scarce. Objectives This study aims to elucidate the relationship between BSI epidemiology and the predictors of IE, as well as the use of echocardiographic screening for IE in BSI. Methods Single-centre registry included all BSI of consecutive hospitalised patients from January 2015 to December 2021. IE prevalence and echocardiographic screening were assessed, also aggregating according to typical species by the European Society of Cardiology and by 2023 Duke-International Society for Cardiovascular Infectious Diseases. Results From 4939 BSIs related to 4242 admissions in 3708 patients, 2.7% had a diagnosis of definite IE. The most prevalent BSI pathogens were Enterobacterales (48.3%) and Staphylococcus aureus (11.5%). Some less frequent BSI presented the highest IE proportions: Streptococcus bovis complex (19.2%) and Listeria monocytogenes (16.7%). BSI in patients with intracardiac prosthetic material showed an IE prevalence almost five times higher than overall BSI. The IE risk was underestimated when micro-organisms were grouped as suggested by the main guidelines. Echocardiography screening was highest for S. aureus (75%) and Staphylococcus lugdunensis (72.2%). Among BSI without IE cases, the echocardiography range was between 27.3% and 59.4%. Conclusions The study illustrates a discrepancy between BSI pathogen prevalence and their IE risk, emphasising the need for sufficient granularity in defining species typically linked to IE. Typical microorganism concepts may underestimate high risk if species are grouped or if IE risk factors are ignored. There is a mismatch between efforts to diagnose definite IE via echocardiography for each microorganism and the IE risk associated with BSI.