This study will be conducted in two phases: Phase 1b will to evaluate the safety and tolerability of multiple ascending intravenous (IV) doses of AP-SA02 or placebo as an adjunct to best available therapy (BAT) compared to BAT alone in subjects with SA bacteremia (SAB). Phase 2a will evaluate the efficacy, safety, and tolerability of multiple doses of AP-SA02 or placebo as an adjunct to BAT compared to BAT alone in subjects with complicated SAB.