From the Guidelines
Patients with Methicillin-Sensitive Staphylococcus aureus (MSSA) bacteremia should generally receive an echocardiogram to evaluate for infective endocarditis, as recommended by the 2015 ESC guidelines for the management of infective endocarditis 1. The preferred approach is to obtain a transesophageal echocardiogram (TEE) as it has higher sensitivity than transthoracic echocardiogram (TTE) for detecting vegetations and abscesses. If TEE is not immediately available or contraindicated, a TTE should be performed initially. The timing of echocardiography should be within the first few days of identifying the bacteremia. This recommendation is particularly important for patients with risk factors such as prolonged bacteremia (>48-72 hours), community-acquired infection, presence of intracardiac devices, intravenous drug use, previous valve disease, or absence of a removable focus of infection. Echocardiography helps determine the presence of endocarditis, which significantly impacts treatment duration (typically 2 weeks for uncomplicated bacteremia versus 4-6 weeks for endocarditis) and the need for potential surgical intervention. Early detection of cardiac involvement is crucial for optimizing outcomes in MSSA bacteremia. Some key points to consider when evaluating MSSA bacteremia include:
- The role of echocardiography in suspected infective endocarditis, as outlined in the 2015 ESC guidelines 1
- The importance of TEE in detecting vegetations and abscesses, particularly in patients with prosthetic valves or intracardiac devices 1
- The recommendation for echocardiography in all adult patients with bacteremia, as stated in the 2011 IDSA guidelines for the treatment of MRSA infections 1 In summary, echocardiography is a crucial diagnostic tool in the evaluation of MSSA bacteremia, and its use should be guided by the most recent and highest-quality evidence, such as the 2015 ESC guidelines 1.
From the Research
MSSA Bacteria and Echocardiography
- The decision to perform an echocardiogram on patients with MSSA bacteria depends on various factors, including the presence of endocarditis symptoms and the patient's overall health condition 2.
- Studies have shown that MSSA bacteremia is associated with higher rates of endocarditis compared to MRSA bacteremia, highlighting the importance of echocardiography in diagnosing endocarditis in MSSA patients 2.
- Echocardiography can help identify cardiac valvular vegetations attributable to S. aureus ABE, which may be visualized as early as a week after the onset of valvular infection 3.
Diagnostic Criteria
- Patients with MSSA bacteremia should be aggressively evaluated for endocarditis, especially if they have a history of intravenous drug use, prosthetic valves, or other risk factors 2.
- The presence of fever, high-grade/continuous bacteremia, and other symptoms consistent with endocarditis should prompt further investigation with echocardiography 3.
- Transesophageal echocardiogram (TEE) or transthoracic echocardiogram (TTE) can be used to evaluate patients with suspected endocarditis, with TEE being more sensitive for detecting valvular vegetations 2.
Treatment and Outcomes
- The treatment of MSSA infective endocarditis typically involves antibiotics, such as cefazolin or antistaphylococcal penicillins, with cefazolin being a valuable option for patients with comorbidities or previous renal failure 4, 5.
- Studies have shown that cefazolin and antistaphylococcal penicillins have similar outcomes in terms of mortality and relapse rates, although cefazolin may be associated with fewer adverse events 4, 5.
- The choice of antibiotic therapy should be individualized based on the patient's specific needs and medical history, with consideration of factors such as renal function and potential drug interactions 4, 5.