Experimental Phage Therapy in Treating Klebsiella pneumoniae-Mediated Liver Abscesses and Bacteremia in Mice

Intragastric inoculation of mice with Klebsiella pneumoniae can cause liver abscesses, necrosis of liver tissues, and bacteremia. A newly isolated phage (phi NK5) with lytic activity for K. pneumoniae was used to treat K. pneumoniae infection in an intragastric model. Both intraperitoneal and intragastric administration of a single dose of phi NK5 lower than 2 x 10(8) PFU at 30 min after K. pneumoniae infection was able to protect mice from death in a dose-dependent manner, but the efficacy achieved with a low dose of phi NK5 by intragastric treatment provided the more significant protection. Phage phi NK5 administered as late as 24 h after K. pneumoniae inoculation was still protective, while intraperitoneal treatment with phage was more efficient than intragastric treatment as a result of the dissemination of bacteria into the circulation at 24 h postinfection. Surveys of bacterial counts for mice treated with phi NK5 by the intraperitoneal route revealed that the bacteria were eliminated effectively from both blood and liver tissue. K. pneumoniae-induced liver injury, such as liver necrosis, as well as blood levels of aspartate aminotransferase and alanine aminotransferase and inflammatory cytokine production, was significantly inhibited by phi NK5 treatment. These data suggest that a low dose of phi NK5 is a potential therapeutic agent for K. pneumoniae-induced liver infection.