Summary

The Enteric Reference Laboratory (ERL) typed 723 STEC in 2024, an increase of 26 from the previous year (697 in 2023). The most common serotypes of the 723 total isolates identified were O157:H7 (155, 21.4%) and O26:H11 (140, 19.4%) followed by O128:H2 (85, 11.8%), O91:H14 (49, 6.8%), and O38:H26 (33, 4.6%). O157:H7 and O26:H11 remained the most common serotypes identified with a slight increase in O26:H11 from 17.2% in 2023 to 19.4% in 2024. There was also an increase in O91:H14 rising from the fifth most common at 4.3% in 2023 to the fourth most common in 2024 at 6.8% of all isolates typed. Where subtyping of the stx gene was successful, 107/155 (69.0%) O157:H7 and 71/140 (50.7%) O26:H11 isolates were stx2a positive. This is an increase from 64.2% of O157:H7 and 55.7% of O26:H11 isolates in 2023. For all cases reported as progressing to haemolytic uremic syndrome (HUS) with a typed isolate, 15/17 (88.2%) were stx2a with the remaining two being stx2c, similar to 2023 where 84.6% were stx2a. Also, five of the cases were O157:H7 (29.0%), 11 were O26:H11 (64.7%), with the remaining one being O177:H25 stx2c. All of the isolates associated with HUS were eae positive as well.