Isolation and Characterization of Lytic Phage TUN1 Specific for Klebsiella Pneumoniae K64 Clinical Isolates From Tunisia

Background: Multidrug-resistant Klebsiella pneumoniae spp ( Kp ) are emerging agents of severe infections of the respiratory and urinary tract or wounds, and progression to fatal septicemia. The use of bacteriophages is currently being considered as an effective alternative or adjuvant to antibiotic treatment. Results In this study, we report K-typing of 163 carbapenem-resistant Kp (CRKP) isolated 2014–2018 at the Military Hospital of Instruction of Tunis (MHT), Tunisia, using wzi gene sequencing. Thereby, we found that K64 Kp strains are associated with increased case/fatality rates, especially at the intensive care unit (ICU). Furthermore, we characterized a lytic Kp phage, vB_KpP_TUN1 (phage TUN1), isolated from waste water samples of the ICU at the MHT. Whole genome sequencing showed that this phage belongs to the Podoviridae family and encodes one putative depolymerase specifically digesting K64 Kp capsules. Furthermore, we could successfully assemble phage TUN1 in a non-replicative host ( E. coli ) raising the possibility of in vitro assembly in the absence of live bacterial hosts. Therefore, phage TUN1 is a promising candidate to be used as an adjuvant or an alternative to antibiotic therapy in CRKP infections, facilitating regulatory approval of phage therapy. Conclusions The lytic phage TUN1, efficiently lyses K64 Kp strains associated with increased case/fatality rates at body temperature. Together with its ability to be rescued in a non-replicative host these features enhance the utility of this phage as antibacterial agent.