Clinical Report: Comparison of T2Bacteria Testing and Blood Cultures for Assessing Staphylococcus aureus Bacteraemia

Overview

This prospective observational diagnostic study compared serial T2Bacteria (T2B) testing with blood cultures for measuring clearance duration in Staphylococcus aureus bacteraemia and evaluated whether clearance duration predicted deep-seated or metastatic infection and mortality.

Background

Staphylococcus aureus bloodstream infection (SABSI) is associated with high mortality, and its incidence is increasing, largely driven by population aging. Monitoring treatment response currently relies on blood cultures, which may have delayed results, reduced sensitivity after antimicrobial therapy begins, and intermittent negative results despite ongoing bacteraemia. T2B is a rapid, culture-independent assay that detects bacterial DNA directly in whole blood within hours.

Data Highlights

• The study enrolled 56 hospitalized adults with S. aureus bacteraemia.

• Mean time to the last positive result was 3.9 days with T2B compared with 1.7 days with blood culture.

• Deep-seated or metastatic infection occurred in 26.8% of patients, and in-hospital mortality was 25.0%.

• Among patients with prolonged T2B clearance of more than 3 days, 57.1% developed deep-seated or metastatic infection compared with 8.6% of those with shorter clearance; in-hospital mortality was 42.9% versus 14.3%, respectively.

• T2B clearance duration predicted deep-seated or metastatic infection better than blood culture clearance duration, with AUCs of 0.798 and 0.647, respectively.

Key Findings

• T2B remained positive significantly longer than blood culture during serial monitoring.

• Prolonged T2B clearance was significantly associated with deep-seated or metastatic infection and in-hospital mortality.

• T2B clearance duration provided superior prognostic discrimination compared with blood culture for deep-seated or metastatic infection.

• T2B also performed significantly better than blood culture for the combined endpoint of deep-seated or metastatic infection and/or in-hospital mortality, but differences for mortality alone were not statistically significant.

• Because treating physicians were blinded to T2B results, the findings demonstrate prognostic associations rather than proving that T2B-guided management improves outcomes.

Clinical Implications

Persistent molecular detection of bacterial DNA may provide prognostic information beyond conventional blood cultures and could help identify patients at increased risk for deep-seated infection or adverse outcomes. However, the potential use of T2B for risk stratification or individualized treatment remains hypothesis-generating and requires prospective interventional evaluation. The T2Bacteria Panel is no longer commercially available.

Conclusion

Prolonged T2B positivity identified patients at increased risk for deep-seated or metastatic infection and was superior to blood culture clearance duration for predicting these complications in S. aureus bacteraemia. The findings suggest that persistent molecular detection of bacterial DNA may provide prognostic information beyond conventional blood cultures and could inform future molecular monitoring approaches.

Related Resources & Content

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