Isolation, identification and genome sequencing of a virulent phage infecting Enterococcus faecium

Abstract:

[Background] Enterococcus faecium is one of ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens. Due to the resistance to a variety of antimicrobial agents, E. faecium seriously threatens human health and is included in the WHO priority pathogens list for R&D of new antibiotics. [Objective] To isolate, characterize, and sequence the genome of the virulent phage against E. faecium, so as to provide raw materials for the phage therapy of E. faecium. [Methods] A phage strain 1A11 against E. faecium was isolated from pasture sewage. The phage was observed in a transmission electron microscope, and its optimal multiplicity of infection, one-step growth curve, and lysis spectrum were determined. The biological characteristics of the strain were analyzed and the whole genome was sequenced. [Results] E. faecium phage 1A11 had a typical icosahedral head and a long tail, belonging to the Siphoviridae of the Caudovirales. The strain showed the optimum multiplicity of infection of 0.01, a lysis cycle of 70 min, an incubation period of 30 min, and an outbreak period of 40 min. It exerted specific lysis effects on several strains of E. faecium. Phage 1A11 had a genome of 42 750 bp with the GC content of 34.71%, 70 putative open reading frames (ORFs), and no antibiotic resistance genes or virulence genes. It can be used for the phage therapy of E. faecium. [Conclusion] A new strain of E. faecium phage 1A11 was isolated, which has certain research value and application potential, and laid a foundation for the study of E. faecium phage therapy.