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Chapter 38 : Bacteriophage Therapy and Campylobacter
Category: Bacterial Pathogenesis
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This chapter discusses efforts to exploit Campylobacter-specific bacteriophages to reduce the numbers of C. jejuni and C. coli colonizing poultry and contaminating poultry meat products. All the phages reported by investigators in two studies had icosahedral heads and long contractile tails that were classified as members of the Myoviridae. Two phages with head diameters of 140.6 and 143.8 nm and large genome sizes of 320 kb were classified as group I. Five phages classified into group II had average head diameters of 99 nm and average genome sizes of 184 kb. A fourth phage had an icosahedral head that was classified as morphotype B1 of the Siphoviridae, while a fifth phage had an icosahedral head with a short tail of morphotype C1 in the Podoviridae. Campylobacter phages on the skin of retail chicken portions have been recovered at levels of 2 X 103 PFU/10 cm2 and this study found that Campylobacter phage could be isolated from chicken skin only when detectable levels of their host were also present. The spontaneous production of CampMu bacteriophages after bacteriophage therapy is of concern because Mu bacteriophages are potential agents of mutation. Attempts to utilize bacteriophage, initially for typing purposes and more recently for their biocontrol potential, have led to a greater awareness of the role that phage play in the complex ecology of Campylobacter. It should be noted that bacteriophage can shape the evolution of Campylobacter genomes as they do in other bacterial genera.
Transmission electron micrographs of Campylobacter bacteriophage. (A) Bacteriophage CP8 used for phage therapy trials ( Loc Carrillo et al., 2005 ). (B) Bacteriophage CP220 empty capsid after DNA insertion. (C) Bacteriophage NCTC 12677, which is one of the large phage used for phage typing ( Frost et al., 1999 ). (D) Bacteriophage CampMu observed by Scott et al. (2007a ).
Comparison of different phage/host combinations in cecal contents, 48 h after phage was administered to precolonized chickens (n ≥ 5 birds per sample point) together with controls. A single log 7 PFU dose was administered to the treatment group at 25 days of age. Adapted from Loc Carrillo et al. (2005) and Scott et al. (2007a ).
Advantages and disadvantages of bacteriophage therapy over conventional antimicrobial treatments
Practical considerations for phage therapy
Comparison of the effect of different phage/host combinations a