A novel depolymerase encoded by phage P5054 specifically degrades the K57-type capsular polysaccharide of Klebsiella pneumoniae

Abstract Klebsiella pneumoniae is an important pathogen, especially hypervirulent and multidrug-resistant K. pneumoniae , which are increasingly becoming a serious threat to global public health. Bacteriophages and their depolymerases are promising therapeutic alternatives to antibiotics as they are effective against hypervirulent and multidrug-resistant K. pneumoniae infections. In this study, we identified the novel depolymerase K57-Dpo8 from K. pneumoniae phage P5054. K57-Dpo8 exhibited specific depolymerase activity against K57-type capsular polysaccharide, increasing the susceptibility of K57-type K. pneumoniae strains to serum killing, macrophage phagocytosis, and improving survival rates in a murine infection model. K57-Dpo8 could inhibit biofilm formation and degrade formed biofilms. Our results provide evidence that K57-Dpo8 is not only effective for capsular typing of K57-type K. pneumoniae but also represents a promising alternative therapeutic strategy for treating K57-type K. pneumoniae infections.