Experimental phage therapy against lethal lung-derived septicemia caused by Staphylococcus aureus in mice.

Nosocomial respiratory infections caused by methicillin-resistant Staphylococcus aureus (MRSA) can progress to lethal systemic infections. Bacteriophage (phage) therapy is expected to be effective against these critical infections. Previously, phage S13' was proposed as a potential therapeutic phage. We here examined phage treatment in a mouse model of lung-derived septicemia using phage S13'. Intraperitoneal phage administration at 6 h postinfection reduced the severity of infection and rescued the infected mice. Phage S13' can efficiently lyse hospital-acquired MRSA strains causing pneumonia-associated bacteremia in vitro. Thus, phage therapy may be a possible therapeutic intervention in staphylococcal lung-derived septicemia.