Rapid molecular testing for Staphylococcus aureus bacteraemia improves clinical management

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Molecular Diagnostics

Background:

• Staphylococcus aureus bacteraemia (SAB) is a major cause of illness and death.
• Current diagnostic methods for SAB have lengthy turnaround times, leading to delayed or suboptimal patient management.
• Rapid diagnostics are needed to improve outcomes for patients with SAB.

Purpose of the Study:

• To evaluate the impact of rapid molecular detection of Staphylococcus aureus in positive blood cultures on patient management.
• To assess the accuracy and speed of the Xpert MRSA/SA blood culture assay compared to standard methods.

Main Methods:

• Prospective study at two clinical centers.
• Positive blood cultures with Gram-positive cocci were tested using the Xpert MRSA/SA blood culture assay and standard culture-based methods.
• Real-time results were provided to clinicians for patient management.

Main Results:

• The Xpert assay demonstrated 100% agreement with culture results.
• Median turnaround time for the Xpert assay was 1.7 hours, compared to 25.7 hours for standard culture.
• Rapid results led to early management changes in 16.8% of patients, including earlier targeted therapy for SAB and de-escalation of antibiotics.

Conclusions:

• The Xpert MRSA/SA BC assay enables rapid and accurate detection of Staphylococcus aureus in positive blood cultures.
• Early targeted patient management is facilitated by this rapid diagnostic approach.
• Negative results can help de-escalate antimicrobial therapy, particularly for suspected coagulase-negative staphylococci.