Clinical Scorecard: Comparison of T2Bacteria Testing and Blood Cultures for Assessing Staphylococcus aureus Bacteraemia: Duration of Clearance as a Predictor of Metastatic Infection and Mortality

At a Glance

Key Highlights

• T2B remained positive significantly longer than blood culture, with mean last-positive times of 3.9 and 1.7 days, respectively.

• Prolonged T2B clearance of more than 3 days was associated with higher rates of deep-seated or metastatic infection and in-hospital mortality.

• T2B clearance duration showed better predictive performance than blood culture clearance duration for deep-seated or metastatic infection and for the combined endpoint of deep-seated or metastatic infection and/or in-hospital mortality.

Guideline-Based Recommendations

Diagnosis

• The study does not establish a guideline recommendation to use T2B for diagnosis or management. T2B results were withheld from treating physicians, and the authors characterize its potential role in risk stratification or individualized therapy as hypothesis-generating. The T2Bacteria Panel is also no longer commercially available.

Management

• All patients who remained in the study cohort ultimately received appropriate antimicrobial therapy for SABSI based on microbiological susceptibility testing. Detailed antimicrobial regimens were not systematically collected.

Monitoring & Follow-up

• Blood cultures and T2B testing were performed every 48 hours until both methods were negative. The study evaluated whether clearance duration could identify patients at increased risk for deep-seated or metastatic infection and adverse clinical outcomes.

• Patients were also assessed for 30- and 90-day mortality and hospital readmission during follow-up.

Risks

• Blood cultures may have delayed results, reduced sensitivity after antimicrobial therapy begins, and intermittent negativity despite ongoing bacteraemia.

• Accurately distinguishing complicated from uncomplicated SABSI can be difficult; the article notes prior evidence that up to one-third of cases initially classified as uncomplicated were subsequently reclassified as complicated.

Patient & Prescribing Data

The study enrolled 56 hospitalized adults with S. aureus bacteraemia. Half of cases were community acquired, and 85.7% of participants were receiving adequate empiric antimicrobial therapy covering S. aureus at study inclusion. All patients who remained in the cohort ultimately received appropriate antimicrobial treatment based on susceptibility testing.

Clinical Best Practices

• Conventional blood cultures remain the current standard for monitoring treatment success in SABSI; this study does not establish serial T2B testing as a clinical standard.

• Persistent molecular detection of bacterial DNA may provide prognostic information beyond conventional blood cultures, but its role in guiding management requires prospective interventional evaluation.

• Prolonged T2B positivity identified patients at increased risk for deep-seated or metastatic infection and may indicate a need for intensified diagnostic evaluation for persistent infectious foci; however, the clinical role of T2B-guided management remains hypothesis-generating, and the assay is no longer commercially available.

Related Resources & Content

• Tong SYC, Fowler VG, Skalla L, Holland TL. Management of Staphylococcus aureus Bacteremia: A Review. JAMA. 2025. doi:10.1001/JAMA.2025.4288.

• Liu C, Bayer A, Cosgrove SE, Daum RS, Fridkin SK, Gorwitz RJ, et al. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children. Clinical Infectious Diseases. 2011;52:e18-e55. doi:10.1093/CID/CIQ146.

• Fowler VG, Durack DT, Selton-Suty C, Athan E, Bayer AS, Chamis AL, et al. The 2023 Duke-International Society for Cardiovascular Infectious Diseases criteria for infective endocarditis: Updating the modified Duke criteria. Clinical Infectious Diseases. 2023;77:518-526. doi:10.1093/CID/CIAD271.

• Peri AM, O’Callaghan K, Rafiei N, Graves B, Sinclair H, Brischetto A, et al. Persistence of detectable pathogens by culture-independent systems (T2 Magnetic Resonance) in patients with bloodstream infection: Prognostic role and possible clinical implications. Clinical Infectious Diseases. 2024;78:283-291. doi:10.1093/CID/CIAD663.

• Fiala J, Palraj BR, Sohail MR, Lahr B, Baddour LM. Is a single set of negative blood cultures sufficient to ensure clearance of bloodstream infection in patients with Staphylococcus aureus bacteremia? The skip phenomenon. Infection. 2019;47:1047-1053. doi:10.1007/S15010-019-01339-W.

• Go JR, Baddour LM, Lahr BD, Sohail MR, Palraj R. The skip phenomenon in Staphylococcus aureus bacteremia: Clinical implications. Diagnostic Microbiology and Infectious Disease. 2022;104. doi:10.1016/J.DIAGMICROBIO.2022.115802.