Isolation and biological characterization of a novel virulent phage targeting Stenotrophomnas maltophilia

Abstract:

[Background] Stenotrophomonas maltophilia is an opportunistic pathogen that exists widely in hospitals and environments,with intrinsic antibiotic resistance.[Objective] This study aims to isolate virulent phages to provide an alternative therapeutic method for S.maltophilia infection.[Methods] A phage was isolated from hospital sewage with a clinical strain of S.maltophilia as the host.The phage genome was sequenced on Illumina platform and its morphology was observed with transmission electron microscopy.The one-step growth curve was established by double-layer plate method.[Results] The isolated phage vB_SmaS_P11 had an icosahedral head and a long tail,belonging to Siphoviridae of Caudovirales.The genome of the phage had a length of 44 600 bp and the G+C content of 63.7%,encoding 66 open reading frames (ORFs),with no tRNA,virulence genes or resistance-related regions.The phage vB_SmaS_P11 was able to lyse 7 strains among 18 clinical isolates of S.maltophilia.The one-step growth curve showed that the strain had the latent time less than 5 min,the lysis period of about 60 min,and the burst size of 100 plaque forming units per cell,which indicated high virulence.[Conclusion] The isolated phage vB_SmaS_P11 is a novel virulent phage targeting S.maltophilia,which provides a candidate phage for treating S.maltophilia infection in the future.

Key words:Stenotrophomonas maltophilia;phage;biological characterization;genomic analysis