In tropical northern Australia, approximately 20% of Staphylococcus aureus bacteremia is caused by methicillin-resistant Staphylococcus aureus (MRSA). We prospectively evaluated the impact on clinician antibiotic prescribing of the results obtained from performing the GeneXpert MRSA/SA test on 151 positive blood cultures with clustered gram-positive cocci. The GeneXpert result led to earlier appropriate prescription of vancomycin for 54% of patients with MRSA; 25% of patients avoided vancomycin, and 16% of patients had all antibiotics ceased.