Free-range layer chickens as a source of Campylobacter bacteriophage

Bacteriophage specific for Campylobacter were isolated from chicken excreta collected from established free-range layer breed stock. Bacteriophage were either propagated on a Campylobacter jejuni host with broad susceptibility to bacteriophage (NCTC 12662) or on Campylobacter isolates from the same samples. Campylobacters were confirmed as being C. jejuni and or C. coli, using a combination of standard biochemical tests and PCR analysis with genus and species specific primers. The bacteriophage displayed differential patterns of susceptibility against reference NCTC strains and contemporary C. jejuni /C. coli isolates from chicken excreta. Electron microscopy demonstrated that the phage possessed icosahedral heads and rigid contractile tails. Pulsed-field gel electrophoresis revealed the bacteriophage genomes to be double stranded DNA in the range of 140 kb in size and the restriction enzyme patterns of the DNAs indicate they are genetically related members of the Myoviridae family. This study showed that Campylobacter bacteriophage could easily be isolated from free-range chickens and form part of their normal microbiological biota of environmentally exposed birds.