In vitro and in vivo assessments of two newly isolated bacteriophages against a ST13 urinary tract infection Klebsiella pneumoniae. Klebsiella pneumoniae

Antibiotic resistance represents a major public health concern requiring new alternatives including phage therapy. Klebsiella pneumoniae belongs to the ESKAPE bacteria and can cause urinary tract infections (UTIs). In this work, two bacteriophages were firstly isolated against a ST13 K. pneumoniae isolated from a UTI and identified as a K3 capsular type by the wzi gene PCR. Both bacteriophages were characterized in vitro and, then, their in vivo efficacy was assessed in the Galleria (G.) mellonella larvae model. Genomic analysis showed that these bacteriophages, named vB_KpnP_K3-ULINTkp1 and vB_KpnP_K3-ULINTkp2, belong to the Drulisvirus genus. The bacteriophage vB_KpnP_K3-ULINTkp1 had the narrowest host spectrum (target only K3) compared to the second which also infected other Klebsiella types. Short adsorption times and latent periods were observed for both bacteriophages. In vivo experiments showed their ability to replicate into G. mellonella larvae and to decrease the bacterial titers. Moreover, both bacteriophages improved the survival of the infected larvae. In conclusion, these two bacteriophages had different in vitro properties and showed in vivo efficacy in the G. mellonella model with a better efficiency for vB_KpnP_K3-ULINTkp2.