Plasmid ampC β-lactamase genes were detected in 19% of phenotypic AmpC-producing Escherichia coli isolates.

The CIT group was the most common plasmid ampC family type (n = 14).

PFGE typing and MLST analysis revealed these isolates were not clnally related, with the exception of two isolates that had an identical sequence type (ST720).

Establishing the prevalence and clonality of Escherichia coli habouring plasmid-mediated AmpC is important in order to implement evidence-based infection control measures.