IDSA Addresses Critical Questions on Staph aureus Bacteremia

The current paradigm of defining Staphylococcus aureus bacteremia (SAB) as "complicated" or "uncomplicated" is inadequate to guide diagnostic evaluation and management, according to a 2026 clinical practice guideline in joint development by the Infectious Diseases Society of America (IDSA) and the European Society of Clinical Microbiology and Infectious Diseases (ESCMID).¹

In the introductory statement, the guidelines suggest there can be an alternative framework, "that is individualized according to clinical presentation and risk factors for deep-seated and metastatic foci.

"Additionally, the diagnostic evaluation and management of SAB should be guided by ongoing reassessment of disease evolution and modified accordingly based on a precise clinical diagnosis," indicate Catherine Liu, MD, Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center and Division of Allergy and Infectious Diseases, University of Washington, Seattle, WA, and coauthors of this section.

The guideline presents consensus statements on 7 clinical questions (abridged below):

• Which risk factors are associated with deep-seated or metastatic foci of infection, or relapse of infection?
• Should follow-up blood cultures be performed until negative?
• Should a transthoracic echocardiogram (TTE) be performed?
• If TTE is negative, should a transesophageal echocardiogram (TEE) be performed?
• Should whole-body imaging be performed it there is increased risk for deep-sedated or metastatic foci of infection and unknown focus after appropriate initial evaluation?
• If there is absence of, and low risk for deep-seated or metastatic foci of infection, should antibiotic treatment be provided for 14 days, or for shorter or longer duration?
• If at increased risk, but without deep-seated or metastatic foci of infection, should antibiotic treatment be provided for 14 days or longer?

Consensus Statements

Considering risk, the guidelines indicate that individual factors are insufficient to exclude the possibility of deep-seated or metastatic foci of infection or of relapse, and so suggest a stratification approach with consideration of key risk factors:

• community-onset SAB, positive blood culture ≥48 hours after first positive culture, presence of an intracardiac device; AND other risk factors, such as:
• predisposing heart valve complications, injection drug use, endovascular graft, SAB in prior 90 days, or signs/symptoms of deep-seated or metastatic focus of infection, embolic events, more than one non-contiguous focus of infection and unknown focus.

On using follow-up blood cultures until negative for SAB, the guidelines suggest obtaining at least 2 sets of cultures at 48 hours after first positive culture, and 1 or 2 sets to be repeated every 24 to 48 hours until negative.

To the question of performing TTE in patients with SAB, the guidelines suggest it should be performed in all adults, and in children who have structural heart disease, prolonged bacteremia, or signs/symptoms consistent with endocarditis.

The guidelines support obtaining TEE in adults if TTE is negative if there is increased risk for endocarditis due to: intracardiac device, predisposing heart valve conditions, positive culture ≥48 hours after first positive culture, embolic event, or more than one non-contiguous focus of infection.

The guidelines do not support TEE in most pediatric patients with SAB having a good quality TTE image, as it finds limited additional diagnostic utility. TEE should be considered for pediatric patients when there is a high clinical suspicion of endocarditis, however, even when TTE is negative.

The use of whole-body imaging (eg, [18F]FDG-PET/CTs or combinations of imaging modalities) is suggested for adults with SAB at increased risk for deep-seated or metastatic foci of infection and an unknown focus after initial evaluation.The guidelines also support whole-body imaging for pediatric patients in "carefully selected situations", which include ongoing SAB without identifiable focus despite targeted evaluation.

The duration of antibiotic therapy for adult and pediatric patients with low-risk SAB and absence of deep-seated or metastatic foci of infection should be 14 days, state the guidelines, "rather than longer or shorter courses".A 14-day regimen is also recommended for adult and pediatric patients with increased-risk SAB but without deep-seated or metastatic foci of infection.

Reference

1. IDSP and ESCMID. 2026 Clinical Practice Guideline by the Infectious Diseases Society of American and European Society of Clinical Microbiology and Infectious Diseases on Staphylococcus aureus Bacteremia: Risk Stratification, Diagnostic Evaluation, and Management of Adults and Children. https://www.idsociety.org/practice-guideline/staphylococcus-aureus-bacteremia/. Accessed July 14, 2026.