Abstract Aims Multidrug-resistant Citrobacter freundii, particularly isolates carrying extended-spectrum β-lactamases and carbapenemases are increasingly difficult to treat in clinical settings. To explore alternatives to antibiotics, we isolated a novel lytic bacteriophage from hospital wastewater in Zhengzhou and designated it vBCfHW01. Methods and Results TEM revealed a siphovirus with a 50 nm capsid and 160 nm tail. Genomic analysis identified vBCfHW01 as a novel Drexlerviridae species. Our results indicated an optimal MOI of 0. 001, defined as the initial infection ratio that yielded the highest progeny titer. The lysis curve showed that vBCfHW01 effectively inhibited host cell proliferation at this low MOI. Adsorption kinetics and one-step growth assays showed 97. 17% adsorption within 14 min, a 10 min latent period, and a burst size of 256 PFU cell−1. The phage remained stable from -20 to 60°C and pH 4 to 10, resisted chloroform exposure, and retained residual infectivity after 90 min of UV irradiation. Sequencing revealed a 49563 bp linear dsDNA genome (Accession: PX694430. 1) containing 94 open reading frames. Genomic analysis identified no known virulence or antibiotic resistance genes. CLSM with live/dead staining showed severe disruption of mature C. freundii biofilms after a 12 h of vBCfHW01 treatment. Live cell coverage decreased from 9. 17 ± 0. 70% to 3. 03 ± 0. 92%, whereas dead cells increased from 0. 14 ± 0. 01% to 7. 87 ± 0. 18%. In an in vivo Galleria mellonella infection model, a single phage dose (MOI 10) rescued 36. 67% of infected larvae. Conclusions Thus, vBCfHW01 is a promising candidate against drug-resistant C. freundii infections.
Zhang et al. (2026) studied this question.