Approximately 11% of the Clostridium difficile genome is
made up of mobile genetic elements (MGEs) [1] which provides
the bacterium with a remarkable genetic plasticity.
However the exact role of the mobile genome in the organism's
biology, evolution and pathogenicity is only now beginning to
be understood.
MGEs are highly heterogeneous and here we will define
them in the loosest possible terms as any region of nucleic acid
that can move from one part of a genome to another or between
genomes. By this definition, MGEs range from the
simple insertion sequences which contain only the genetic
information required for movement from one part of the
genome to another, to bacteriophage, large conjugative transposons
and mega plasmids which are complex genomes in
themselves. In this review we will provide examples of some