From the Guidelines
Yes, an echocardiogram is strongly recommended for patients with Staphylococcus aureus bacteremia (SAB) of unknown origin. According to the most recent and highest quality study, the 2015 ESC guidelines for the management of infective endocarditis 1, echocardiography should be considered in Staphylococcus aureus bacteremia. Transthoracic echocardiography (TTE) should be performed initially in all patients with SAB, and if the TTE is negative but clinical suspicion for endocarditis remains high, a transesophageal echocardiogram (TEE) should follow.
This recommendation exists because S. aureus has a high propensity (up to 25-30% of cases) to cause infective endocarditis, which may not be clinically apparent but significantly impacts treatment decisions. The presence of endocarditis would extend antibiotic therapy from the standard 2 weeks to 4-6 weeks, typically with an anti-staphylococcal beta-lactam like nafcillin or oxacillin (or vancomycin for MRSA) at 2g IV every 4 hours.
Some key points to consider:
- Echocardiography should be performed as soon as possible after bacteremia is detected, ideally within 5-7 days, as early detection of endocarditis or other metastatic complications can improve outcomes and guide appropriate treatment duration and intensity.
- The 2015 ESC guidelines also recommend repeat TTE and/or TOE within 5–7 days in case of initially negative examination when clinical suspicion of IE remains high 1.
- Other studies, such as the 2009 update by the Infectious Diseases Society of America 1 and the 2011 clinical practice guidelines for the treatment of MRSA infections 1, also support the use of echocardiography in patients with S. aureus bacteremia, but the 2015 ESC guidelines are the most recent and highest quality study.
Overall, the use of echocardiography in patients with S. aureus bacteremia of unknown origin is crucial for detecting potential endocarditis and guiding treatment decisions, and it is strongly recommended to perform an echocardiogram in these patients.
From the Research
Echocardiogram Recommendation for Staph Aureus Bacteremia of Unknown Origin
- Echocardiography is essential in evaluating patients with Staphylococcus aureus bacteremia, especially in identifying infective endocarditis (IE) and its associated complications 2.
- The use of transesophageal echocardiography (TEE) is recommended as it has a higher sensitivity compared to transthoracic echocardiography (TTE) in detecting IE 2, 3.
- TEE should be considered part of the early evaluation of patients with Staphylococcus aureus bacteremia, particularly in those with a high risk of endocarditis, such as patients with persistent bacteremia, persistent fever, metastatic infection foci, or implantable cardiac devices 2, 4.
- Clinical findings and predisposing heart disease do not distinguish between patients with and without IE, emphasizing the importance of echocardiography in diagnosis 2.
- The overall prevalence of possible or definite IE on TEE-inclusive Duke criteria can be as high as 29%, with a significant portion of cases not suspected clinically 3.
- Echocardiography can help guide the length of therapy and distinguish between simple and uncomplicated bacteremias from true cases of infective endocarditis 5.
- All patients with Staphylococcus aureus bacteremia should undergo transthoracic echocardiography, with transesophageal echocardiography performed in patients at high risk for endocarditis 4.