Abstract:
Colibacillosis is one of the most catastrophic disease of poultry worldwide, responsible for
increased mortality that leads to major economic losses. As antibiotic resistant strains are
prevailing, alternative strategies are being suggested to control the infection, one of them is “phage
therapy. In post-antibiotic era, phage therapy is a potential alternative treatment as bacteriophages
are specific to host cells causing no harm to eukaryotic cells and commensal microflora. In this
study; 2 lytic phages, PBM-1 and PBM-2 were isolated from poultry bedding material taken from
different sheds of same poultry farm. The isolated phages showed clear plaques on lawn of Avian
Pathogenic E. coli O1 (APEC-O1) with no attributes of lysogeny. Transmission electron
microscopy revealed that both phages belong to Myoviridae with an icosahedral head and a
contractile tail. Host range was examined against 40 clinical pathogenic strains and both phages
showed infectivity against 10 APEC strains. PBM-1 and PBM-2 showed a high adsorption rate
over 90% and 95% to host bacterium over a short period of time. Stability studies showed that
both phages were stable over a wide range of temperature and pH. Bacterial cell lysis assay
revealed that both phages can reduce the bacterial growth up-to 6 hours. Latent period of PBM-1
and PBM-2 is 20 and 25 mins having a burst size of 102 and 97 virions per bacterium. Our results
indicate that both studied phages are potential candidates for use in phage therapy. Further genomic
and proteomic analysis will help to unravel the therapeutic potential of these phages.
