Isolation and characterization of Klebsiella pneumoniae phage. Morphological and genomic analysis of Drulisvirus infecting Extended-Spectrum β-lactamases-producing Klebsiella pneumoniae

Background: The increasing incidence of infections caused by extended-spectrum β-lactamase-producing Klebsiella pneumoniae (ESBL-KP) in Indonesia necessitates the investigation of phage therapy as a potential alternative treatment strategy. Materials and methods: A phage capable of infecting ESBL-KP was isolated from the Cideng River in Indonesia, and subsequently characterized morphologically and genomically. Results: A novel lytic phage, designated JKT1, was exhibiting an icosahedral head (±52 nm diameter), a short tail, and the formation of large plaques with halos on bacterial lawns. JKT1 demonstrated rapid adsorption, a high burst size, and a narrow host range. The phage remained stable at neutral pH and up to 37°C, with activity declining at 50°C. JKT1 effectively inhibited ESBL-KP clinical isolates and possesses a 43,763 bp linear dsDNA genome containing 57 ORFs, classifying it within the Drulisvirus genus. Conclusions: This study demonstrates JKT1's activity against K12 capsular ESBL-KP, highlighting its targeted host range and potential for inclusion in phage cocktails targeting bacterial infections.