This is a multi-center, preclinical study to investigate the effectiveness of the performance of MicroPhage S. aureus / MSSA/MRSA test direct for blood culture. There will be no patient consent, as this is a laboratory performance study on leftover specimens. The MicroPhage test will be compared to site standards (gold standard) and market-available tests with similar indications (comparators). MicroPhage will require data to be collected at 4 hours and 5 hours following the start of the MicroPhage test. The study will last 2-3 months, depending on the accrual rate of the institution.