Work

Biological and genomic characterization of Escherichia phage KBU_SV1 active against carbapenem-resistant Escherichia coli

Year: 2026

Type: article

Abstract: Carbapenem-resistant Escherichia coli infections are increasingly difficult to treat, and bacteriophages have been highlighted as a promising tool to control such multidrug-resistant bacteria. Here, we isolated and characterized Escherichia phage KBU_SV1 using E. coli ATCC 25922 as the isolation and propagation host. Its morphology, host range, stability at various temperatures and pH, reduction growth of bacteria, effect on biofilm, in vivo efficacy, and genome were investigated. Transmission electron microscopy showed a polyhedral head and a long, non-contractile tail, corresponding to a siphovirus morphotype. The spot-test analysis of 106 bacterial strains showed spot clearance against 16 strains (host range index, 0.15), including carbapenem-resistant and carbapenem-susceptible E. coli isolates and, to a lesser extent, Klebsiella pneumoniae , while no such effect was observed in the other species tested. KBU_SV1 was stable between pH 4 and 12 and at 4–37 °C, but no infectivity was detected at pH 2 or 65 °C. Bacterial growth was suppressed at all multiplicities of infection (MOI) tested (100–0.01), followed by gradual regrowth. KBU_SV1 reduced established biofilms and inhibited biofilm formation in both E. coli ATCC 25922 and the carbapenem-resistant isolate Ec59. In the Galleria mellonella infection model, phage treatment significantly delayed larval mortality compared with the infection control, while no mortality occurred in larvae receiving phage alone. The genome of KBU_SV1 was found to be 45,190 bp with a G + C content of 53.56% and was complete with a 272-bp direct terminal repeat. The genome contains 71 putative open reading frames (ORFs) and no tRNA, while no virulence, antibiotic resistance (AMR) or lysogeny-associated genes were identified, and genome-based analyses predicted a virulent lifestyle. Comparative genomic analysis showed a high nucleotide identity (99.12%) with Escherichia phage EPIMAM03, and KBU_SV1 was assigned to the genus Dhillonvirus within the class Caudoviricetes . All these results showed that KBU_SV1 has favorable properties such as antibacterial potential against carbapenem-resistant E. coli , broad stability, antibiofilm and in vivo activity, and the absence of virulence and AMR genes. Based on all these features, this newly isolated phage is promising for the control of carbapenem-resistant E. coli infections, alone or in phage cocktails.

Source: Frontiers in Microbiology

DOI: 10.3389/fmicb.2026.1927801

Authors: Sevil Öztaş, Abdulkerim Karaynir, Rumeysa Gulsu Ozkan, Bulent Bozdogan, Devrim Dündar

Institutions: Karabük University, Adnan Menderes University, Kocaeli Üniversitesi

Language: English

Topic: Bacteriophages and microbial interactions

Subfield: Virology

Field: Immunology and Microbiology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $3,801