A novel lytic bacteriophage, XANXB1, was isolated from hospital wastewater through host bacterial enrichment and evaluated for its potential in controlling multidrug-resistant Stenotrophomonas maltophilia infections. Transmission electron microscopy revealed that XANXB1 has a long tail, possessing an icosahedral head of ~80 nm in diameter and a tail measuring ~150 nm in length. It produced clear plaques of 0. 5–1 mm on host bacterial lawns. Host range analysis demonstrated its ability to infect multiple multidrug-resistant S. maltophilia isolates. Biological characterization showed that the phage is chloroform-insensitive, retains strong lytic activity across a wide temperature (4–60 °C) and pH (3. 0–10. 0) range, and achieves more rapid host suppression under higher multiplicity of infection (MOI). Whole-genome sequencing determined a ~47 kb double-stranded DNA genome encoding 71 predicted open reading frames, with no known virulence or antibiotic resistance genes. Phylogenetic analysis of MCP and terminase large subunit sequences placed XANXB1 in a unique Caudoviricetes, with ANI values below the 95% ICTV threshold verifying its status as a novel phage species. The XANXB1 therapy significantly alleviates S. maltophilia infection-induced severe pulmonary inflammatory lesions, high mortality, elevated serum inflammatory factors and massive pulmonary bacterial colonization in male BALB/c mice, confirming its favorable therapeutic effect on such infections. Collectively, these results reveal that is an efficacious candidate for therapeutic development against S. maltophilia infections.
Yang et al. (Sun,) studied this question.