Should we check for endocarditis immediately in patients with Staphylococcus (Staph) bacteremia and an indwelling catheter, or only when blood cultures do not clear?

Evaluation for Endocarditis in Staph Bacteremia with Indwelling Catheter

You should check for endocarditis immediately with echocardiography in all patients with Staphylococcus aureus bacteremia, regardless of catheter presence, rather than waiting for culture clearance. 1

Immediate Echocardiography is Standard of Care

• Echocardiography is recommended for ALL adult patients with S. aureus bacteremia as part of the initial evaluation 1
• The minimum evaluation should include echocardiography alongside history, physical examination, infectious diseases consultation, and follow-up blood cultures 1
• This applies universally to catheter-related S. aureus bacteremia, not just cases with persistent positive cultures 1

Why TEE Should Be Done Early (Not After Culture Failure)

• 25-32% of patients with S. aureus bacteremia have endocarditis detected by transesophageal echocardiography (TEE), many of which are not clinically suspected 1
• In catheter-related S. aureus bacteremia specifically, 23% had endocarditis documented by TEE using Duke criteria 1
• TEE should be performed 5-7 days after onset of bacteremia to minimize false-negative results, not delayed until cultures fail to clear 1, 2
• Transthoracic echocardiography (TTE) has only 27-32% sensitivity for detecting endocarditis in S. aureus bacteremia and is insufficient to rule out infective endocarditis 1

The Algorithm for Echocardiography Timing

For catheter-related S. aureus bacteremia:

1. Remove short-term catheters immediately 1
2. Obtain TEE within 5-7 days of bacteremia onset (not after waiting for culture results) 1
3. Obtain follow-up blood cultures at 2-4 days after starting therapy to document clearance 1
4. If cultures remain positive ≥72 hours after catheter removal and appropriate antibiotics, obtain additional TEE if earlier TEE was negative and no undrained metastatic infection is present 1

Clinical Predictors That Support Immediate Evaluation

High-risk features that mandate aggressive early evaluation (including TEE):

• Community-acquired infection 1, 3
• Underlying valvular heart disease or prior endocarditis 3
• Intravenous drug use 3
• Unknown portal of entry 3
• Prosthetic valve or other implanted prostheses 1
• Hemodialysis dependence 1
• Immunosuppression (HIV/AIDS, diabetes, immunosuppressive medications) 1

Why Waiting for Culture Clearance is the Wrong Approach

• Persistent bacteremia ≥72 hours is a predictor of complications including endocarditis, but absence of persistent bacteremia does NOT exclude endocarditis 1, 2, 3
• Many endocarditis cases clear their blood cultures appropriately but still have valvular vegetations requiring prolonged therapy 1
• The purpose of TEE is to determine duration of therapy (2 weeks vs 4-6 weeks), not just to evaluate treatment failure 1
• Waiting for culture results delays critical diagnostic information that directly impacts treatment duration and prognosis 1

Treatment Duration Depends on TEE Results (Not Culture Clearance Alone)

For uncomplicated catheter-related S. aureus bacteremia with negative TEE:

• 14 days of therapy if: negative TEE, cultures clear by 2-4 days, defervescence within 72 hours, no metastatic sites, no prosthetic devices 1

For endocarditis or complicated bacteremia:

• 4-6 weeks of therapy regardless of when cultures clear 1

Common Pitfalls to Avoid

• Relying on TTE alone—it misses 68-73% of endocarditis cases in S. aureus bacteremia 1
• Assuming that rapid culture clearance excludes endocarditis—it does not 1
• Delaying TEE until after cultures fail to clear—this misses the optimal 5-7 day window and delays appropriate therapy duration decisions 1
• Treating all catheter-related S. aureus bacteremia for only 2 weeks without echocardiography—this results in 6% relapse rate with endocarditis or deep tissue infection 1
• Failing to remove the catheter, which increases risk of persistent bacteremia and complications 1, 2