Echocardiography has minimal yield and may not be warranted in Staphylococcus aureus bacteremia without clinical risk factors for endocarditis

Abstract

Current guidelines recommend performing echocardiography in all patients with Staphylococcus aureus bacteremia (SAB), but patients at very low risk of endocarditis may not benefit from this investigation. This study seeks to identify patients at very low risk of endocarditis. A retrospective single-center consecutive case series of patients with SAB was examined. Microbiological and echocardiographic data were used to identify patients with community onset, prolonged bacteremia, and intracardiac prosthetic devices. The diagnostic performance of these criteria for endocarditis as measured against transesophageal echocardiography (TEE) was calculated. 593 episodes of SAB were examined over a period of 6 years. 10 % were excluded from analysis due to death or discharge less than 48 h after the first positive blood culture or no admission to hospital, leaving 532 episodes for analysis. 64 % of the included episodes were investigated with echocardiography: 39 % with TEE and 26 % with transthoracic echocardiography (TTE) only. 16 % of the episodes investigated with echocardiography were demonstrated to have endocarditis. The rate of endocarditis was higher for episodes undergoing TEE (24 %) than TTE only (5 %). There were no instances of endocarditis amongst the 23 episodes investigated with TEE where none of the three risk factors were present. This group represented 57 % of the nosocomial (non-community-onset) episodes investigated with TEE. Patients with none of the three criteria examined in this study have a very low rate of endocarditis and may fall below the test threshold for echocardiography.