Key Inclusion Criteria:  A hospitalized female or male ≥ 18 years old Positive blood culture for Staphylococcus aureus (SA) Source of SA infection controlled, or a plan for source control, if relevant Not pregnant or breastfeeding and is not of reproductive potential or agrees to use contraception if or reproductive potential  Key Exclusion Criteria:  Concomitant growth of organisms besides SA Left-sided infectious endocarditis by modified Duke criteria Known or suspected brain abscess or meningitis Known allergy to phage products