Bacteriophage Treatment against Carbapenem-resistant Klebsiella pneumoniae (KPC) in a Neutropenic Murine Model of Gastrointestinal Translocation and Renal Infection

BackgroundCarbapenemase producing Klebsiella pneumoniae (KPC) are globally emerging pathogens which that cause life-threatening infections. Novel treatment alternatives are urgently needed. MethodsWe therefore investigated the effectiveness of three novel bacteriophages (Spivey, Pharr and Soft) in a neutropenic murine model of KPC gastrointestinal colonization, translocation, and disseminated infection. Bacteriophage efficacy was determined by residual bacterial burden of KPC in kidneys. Parallel studies were conducted of bacteriophage pharmacokinetics and resistance.. ResultsTreatment of mice with 5x109 PFU of phage cocktail via intraperitoneal injection was effective in significantly reducing renal KPC burden by 102 CFU (p<0.01) when administered every 24 hours and 103 CFU (p<0.01) every 12 hours. Moreover, a combination of bacteriophage and ceftazidime-avibactam produced a synergistic effect, resulting in a 105 reduction in bacterial burden in caecum and kidney (p<0.001 in both tissues). Prophylactic administration of bacteriophages via oral gavage did not prevent KPC translocation to the kidneys. Bacteriophage decay determined by linear regression of the ln of mean concentrations demonstrated R2 values in plasma of 0.941, kidney 0.976, and caecum 0.918, with half-lives of 2.5h < t1/2 < 3.5 h. Furthermore, a phage-resistant mutant displayed increased sensitivity to serum killing in vitro, but did not show significant defects in renal infection in vivo. ConclusionsA combination of bacteriophages demonstrated significant efficacy alone and synergy with ceftazidime/avibactam in treatment of experimental disseminated KPC infection in neutropenic mice.