Is echocardiography (echo) necessary for patients with Viridans streptococcus bacteremia?

From the Guidelines

Echocardiography is recommended for patients with Viridans streptococcus bacteremia to rule out infective endocarditis, as it is a common cause of this condition and missing the diagnosis can lead to serious complications. The decision to perform echocardiography should be based on specific clinical criteria, including the presence of cardiac risk factors, clinical signs of endocarditis, and the patient's immune status 1.

Key Considerations

• Patients with a clear source of infection, prompt clearance of bacteremia with appropriate antibiotics, and no cardiac risk factors may be considered low-risk and potentially do not require echocardiography 1.
• However, the decision to forego echocardiography should be made cautiously, as viridans streptococci can cause endocarditis, which can lead to serious complications such as heart failure, embolic events, or death.
• A thorough clinical evaluation, including careful examination for peripheral stigmata of endocarditis and assessment of cardiac murmurs, is essential if echocardiography is not performed 1.

Treatment and Management

• Treatment typically involves 2 weeks of intravenous antibiotics such as penicillin G (3-4 million units every 4 hours) or ceftriaxone (2g daily) for uncomplicated cases 1.
• For complicated cases or those with risk factors, 4-6 weeks of therapy may be needed.
• The choice of antibiotic therapy should be based on the patient's specific clinical situation and the results of susceptibility testing 1.

Echocardiography Recommendations

• Transthoracic echocardiography (TTE) is recommended as the first-line imaging modality in suspected infective endocarditis 1.
• Transesophageal echocardiography (TOE) is recommended in patients with clinical suspicion of infective endocarditis and a negative or non-diagnostic TTE, or in patients with a prosthetic heart valve or an intracardiac device 1.

From the Research

Echocardiography in Viridans Streptococcus Bacteremia

• The use of echocardiography in patients with Viridans streptococcus bacteremia is a topic of interest, particularly in identifying potential complications such as infective endocarditis 2, 3.
• A study published in 2024 found that the incidence of infective complications, including infective endocarditis, was low in cancer patients receiving chemotherapy with Viridans group streptococci bloodstream infection 4.
• The same study assessed the utility of echocardiography in this patient population and found that transthoracic echocardiogram was performed for 71% of episodes, but only one patient met modified Duke's criteria for definite infective endocarditis 4.
• Another study published in 2018 reported a case of a patient with Viridans streptococcal infective endocarditis associated with a fixed orthodontic appliance, where echocardiography played a crucial role in diagnosis and management 2.
• The importance of echocardiography in patients with Viridans streptococcus bacteremia is highlighted by the fact that it can help identify potential cardiac complications, such as mitral valve prolapse, which can increase the risk of infective endocarditis 3.

Antimicrobial Susceptibility and Resistance

• The antimicrobial susceptibility of Viridans group streptococci is an important consideration in the management of patients with bacteremia 5, 6.
• A study published in 2024 found that the lowest penicillin susceptibility was observed in S. alactolyticus group, followed by S. mitis and S. gallolyticus 5.
• Another study published in 1994 found that the emergence of resistant strains is a concern in neutropenic patients undergoing chemotherapeutic treatment 6.
• However, a study published in 2024 found that benzylpenicillin resistance was rare (2.9%) and did not change over time in cancer patients with Viridans group streptococci bloodstream infection 4.

Clinical Implications

• The clinical implications of Viridans streptococcus bacteremia are significant, particularly in patients with underlying medical conditions such as cancer or those undergoing chemotherapeutic treatment 6, 4.
• The use of echocardiography in patients with Viridans streptococcus bacteremia should be considered on a case-by-case basis, taking into account the individual patient's risk factors and clinical presentation 2, 3, 4.
• The management of patients with Viridans streptococcus bacteremia should include appropriate antimicrobial therapy, as well as consideration of potential cardiac complications such as infective endocarditis 2, 3, 5, 6, 4.