Abstract

The development of antimicrobial resistance (AMR) has become a worldwide concern,
with predictions stating that 10 million people may die as a result of AMR by 2050. The
increasing concern surrounding bacterial resistance rendered their use as antimicrobial
growth promotors (AGP’s) within the animal husbandry sector detrimental, resulting in
their ban within Europe in 2006. Since then, a multitude of diseases have arisen, the most
notable being necrotic enteritis in broiler chickens, caused by C. perfringens. The almost
US$6 billion per annum loss associated with the disease, makes the acquisition of an
alternative economically viable. With the use of bacteriophage (phage) commonly
proposed as an alternative to antibiotics, this study aimed to isolate and characterise a
lytic C. perfringens phage from the environment, before establishing therapeutic efficacy.
Sewerage effluent samples were collected in order to screen for C. perfringens phage,
prior to purification and generation of high titre lysate. Molecular characterisation was
then performed via DNA extraction, sequencing, pulsed field gel electrophoresis (PFGE)
and restriction enzyme digests, as well as lytic range studies, visualisation via transmission
electron microscopy (TEM) and burst size and latent period calculation through one-step
growth curve experiments. Results indicated the isolation of a lytic C. perfringens phage,
(named Φ22), and production of a purified, high titre lysate (109 PFU/mL). Visualisation
indicated the classification of Φ22 into the order Caudovirales, within the family
Podoviridae. Within the 39-40nm icosahedral head, double stranded DNA was extracted,
determined to be 17,962 bp in size. A vast lytic range was determined alongside a large
burst size (121 virions per cell) and short latent period (50 minutes), indicating its
favourable use therapeutically and highlighting the pragmatic approach towards an
alternative to antibiotics.