Direct monitoring of meropenem therapeutic efficacy against Klebsiella pneumoniae respiratory infection by bioluminescence imaging.

Introduction. Klebsiella pneumoniae is a major threat to public health worldwide. It is the causative agent for multiple disease presentations including urinary tract infection, septicemia, liver abscess, wound infection and respiratory tract infection. K. pneumoniae causes community- and hospital-acquired pneumonia, which is a devastating disease associated with high mortality rates. Hypothesis. There is a growing concern about the emergence of multidrug-resistant K. pneumoniae strains complicating the treatment with the current available therapeutics; therefore, there is an urgent need for the development of new antimicrobial agents. Aim. K. pneumoniae causes an acute respiratory disease in mice and in the current work we investigated the capability to perform non-invasive monitoring of bioluminescent Klebsiella to monitor therapeutic efficacy. Methodology. We engineered a bioluminescence reporter strain of K. pneumoniae to monitor the impact of antibiotics in a murine respiratory disease model. Results. We demonstrate that bioluminescence correlates with bacterial numbers in host tissues allowing for a non-invasive enumeration of bacterial replication in vivo . Light production is directly linked to bacterial viability, and this novel bioluminescent K. pneumoniae strain enabled monitoring of the efficacy of meropenem therapy in arresting bacterial proliferation in the lung. Conclusion. The use of non-invasive bioluminescent imaging improves preclinical animal model testing to detect study outcome earlier and with higher sensitivity.