Clinical impact of rapid oxacillin susceptibility testing using a PCR assay in Staphylococcus aureus bactaeremia

The aim of this work was to establish the clinical impact of rapid oxacillin susceptibility testing in nosocomial Staphylococcus aureus bacteraemia.

This study was performed in 145 critically ill patients infected by S. aureus. Patients were randomly assigned to one of two groups: patients for whom susceptibility testing was performed using a rapid same day multiplex PCR assay for detection of the staphylococcal mecA (mean delay of response: 6 h) and those for whom testing was accomplished using traditional overnight techniques (21 h).

The results of this study showed no significant difference between the two groups in terms of age, Simplified Acute Physiologic Score, severity of infection, severity of underlying disease and clinical outcome (control vs. PCR): unfavourable outcome of infection, 12.32 vs. 12.5%; 95% CI for the difference = -11.49 to 11.09 (P = 0.975); unfavourable general outcome, 16.43 vs. 20.83%; 95% CI for the difference = -17.35 to 8.50 (P = 0.497). For the oxacillin-susceptible S. aureus bactaeraemia, results were: unfavourable outcome of infection = 13.04 vs. 11.11%; 95% CI for the difference = -11.38 to 16.18 (P = 0.767); unfavourable general outcome = 13.04 vs. 20.37%; 95% CI for the difference = -22.12 to 8.07 (P = 0.331).

This study seemed to demonstrate that rapid oxacillin susceptibility testing using a PCR assay did not have a major impact on the care and outcome of patients with S. aureus bactaeremia.