When should a transesophageal echocardiogram be performed in patients with Staphylococcus epidermidis bacteremia?

When to Obtain TEE for Staphylococcus epidermidis Bacteremia

Start with transthoracic echocardiography (TTE) in all suspected cases, then proceed to transesophageal echocardiography (TEE) if TTE is negative or inadequate AND you have high-risk features present. 1, 2

Initial Imaging Approach

Perform TTE first in all cases of suspected infective endocarditis with S. epidermidis bacteremia 1. This is the standard initial test based on ease of use and availability, though it has lower sensitivity (approximately 50% for prosthetic valve vegetations and 25-40% for device-related infections) 3.

Proceed Directly to TEE When:

High-risk patient features are present:

• Prosthetic heart valves (TTE is inadequate for prosthetic material assessment) 1, 3, 1
• Intracardiac devices (pacemakers, ICDs, leads) 3, 2, 4
• Previous history of endocarditis 1
• New atrioventricular block or conduction abnormalities 1
• New or changing heart murmur 1
• Heart failure symptoms 1

Clinical features suggesting complications:

• Persistent fever despite 48-72 hours of appropriate antibiotics 2, 4
• Persistent bacteremia (positive blood cultures ≥48-72 hours after starting treatment) 5, 4
• Embolic events (stroke, splenic infarct, other septic emboli) 1
• Signs of metastatic infection 2, 5

TEE After Initial Negative TTE:

Obtain TEE as soon as possible if 1:

• Initial TTE is negative or inadequate AND clinical suspicion remains high
• Initial TTE is positive but you need to assess for complications (abscess, perivalvular extension, fistula)
• Prosthetic valves or intracardiac devices are present (TEE sensitivity ~90% vs TTE ~50%) 3

Repeat TEE Timing:

If initial TEE is negative but clinical suspicion persists, repeat TEE in 3-5 days (or sooner if clinical deterioration occurs) 1. Vegetations may reach detectable size or abscesses may become evident in this interval 1.

Important Caveats for S. epidermidis Specifically:

S. epidermidis differs from S. aureus in several critical ways:

• It is a coagulase-negative staphylococcus with lower virulence than S. aureus
• Most commonly associated with prosthetic material and foreign bodies (catheters, prosthetic valves, cardiac devices) 6
• Often represents contamination rather than true bacteremia, requiring clinical correlation
• When causing true bacteremia, it typically involves prosthetic material, making TEE more essential than in native valve disease

Do NOT routinely obtain TEE if:

• Single positive blood culture with S. epidermidis in a patient without prosthetic material (likely contaminant)
• No high-risk features present
• Clear alternative source identified (e.g., peripheral IV site infection) with rapid clearance of bacteremia
• Patient has clear contraindications to TEE and findings would not change management

Practical Algorithm:

1. All S. epidermidis bacteremia → Obtain TTE within 12 hours 1

2. If prosthetic valve/device present → Proceed directly to TEE (can be first test in high-volume centers) 3

3. If TTE negative but:

   • Prosthetic material present, OR
   • Persistent fever >48-72 hours, OR
   • Persistent bacteremia, OR
   • Embolic events

   → Obtain TEE immediately 1, 2

4. If initial TEE negative but suspicion remains → Repeat TEE in 3-5 days 1

5. If clinical deterioration during treatment (new murmur, heart failure, conduction block) → Urgent TEE 1

The key distinction is that S. epidermidis bacteremia almost always involves prosthetic material, making the threshold for TEE lower than with other organisms. TEE has approximately 90% sensitivity for prosthetic valve endocarditis compared to only 50% for TTE 3, making it nearly mandatory when prosthetic material is present and bacteremia is confirmed.