Trends of STM phage types and MLVA patterns over the 3-year study period. A: Monthly counts of STM phage types. Cumulative counts for phage types DT170, DT135 and DT9 are colour-coded. All other phage types are included in 'other' types. B: Monthly occurrence of total MLVA types and novel MLVA types observed. C: Monthly counts of STM isolates included in MLVA clusters. D: Monthly counts of MLVA clusters and trends in MLVA cluster sizes.