In Vitro and In Vivo Assessments of Two Newly Isolated Bacteriophages against an ST13 Urinary Tract Infection .

Antibiotic resistance represents a major public health concern requiring new alternatives including phage therapy. belongs to the ESKAPE bacteria and can cause urinary tract infections (UTIs). The aims of this study were to isolate and characterize new bacteriophages against a strain isolated from UTIs and to assess their efficacy in vitro and in vivo in a larvae model. For this purpose, two bacteriophages were newly isolated against an ST13 strain isolated from a UTI and identified as K3 capsular types by gene PCR. Genomic analysis showed that these bacteriophages, named vB_KpnP_K3-ULINTkp1 and vB_KpnP_K3-ULINTkp2, belong to the genus. Bacteriophage vB_KpnP_K3-ULINTkp1 had the narrowest host spectrum (targeting only K3), while vB_KpnP_K3-ULINTkp2 also infected other types. Short adsorption times and latent periods were observed for both bacteriophages. In vivo experiments showed their ability to replicate in larvae and to decrease host 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 a model with a better efficiency for vB_KpnP_K3-ULINTkp2.