Isolation and characterization of virulent bacteriophages against Klebsiella pneumoniae of significant capsular types

Abstract

The growing proportion of antibiotic-resistant Klebsiella pneumoniae strains raises challenges to the healthcare system and requires the development of alternative treatment options. Bacteriophage therapy is one of such options. The study was aimed to isolate and describe bacteriophages effective against K. pneumoniae strains of clinically significant capsular types. The bacteriophages were isolated from the sewage and river water samples using the enrichment culture technique. The spectrum of lytic activity of the phages was tested on the collection of K. pneumoniae clinical isolates (n = 279). The studied bacteriophages lysed 52.8–100% of K. pneumoniae strains of respective capsular types: phage VKV295 lysed 100% of strains with the capsular type KL1, SAA231 — 52.8 of strains with KL2, NNK-G4 — 100% of strains with KL39, VSG32 — 66.7% of strains with KL41, NKA196 — 87.5% of strains with KL47, Rappa3 — 87.5% of strains with KL57, PEA128 — 95.5% of strains with KL64, and ChM-G5 — 69.6% of strains with KL102. Whole-genome sequencing and subsequent bioinformatic analysis revealed that the phages belong to the Autographiviridae family and are classified into three genera.The lytic spectrum of phages was limited to specific capsular types due to the presence of specific receptor-binding proteins, polysaccharide depolymerases. The isolated bacteriophages were strictly virulent, did not carry harmful genetic determinants, and had a specific host range, making them applicable in therapeutic practice for combating antibiotic-resistant infections caused by K. pneumoniae.