Characterization of a Novel Lytic Bacteriophage φEC14 that Infects Enterobacter cloacae Clinical Isolates

Enterobacter cloacae, an important agent associated with nosocomial infection, usually involves expanded-spectrum cephalosporin resistance. The therapeutic potential of bacteriophage is a possibly alternative chemotherapy against bacterial infection. In this study, we have characterized one newly isolated bacteriophage φEC14, which is lytic to E. cloacae specifically. Transmission electron microscopy revealed that phage φEC14 had an icosahedral head and long contractile tail, morphologically similar to phages belonging to family Siphoviridae. Pulsed-Field Gel Electrophoresis (PFGE) showed that the size of φEC14 virion DNA was in rang of 23.0-48.5 kb. Restriction analysis showed that lytic phage φEC14 was a double-stranded DNA virus, which might be cut by some restriction endonucleases. SDS-PAGE of phage proteins exhibited one major band and six minor bands with molecular weight ranging from 6.5 to 66.4 kilo-Dalton. In one-step experiment, phage φC14 had a short latent period of 10 minutes and a burst size of 50 PFU/cell. The best understanding of the biological features of lytic bacteriophage φEC14 would facilitate the development of an alternative agent to control the spread of multidrug-resistant E. cloacae