The New Zealand Institute for Public Health and Forensic Science (PHF Science) was formerly named The Institute of Environmental Science and Research (ESR).

2023 - STEC isolates

Please note: As of 1 July 2025, the New Zealand Institute for Public Health and Forensic Science (PHF Science) is the new name for the Institute of Environmental Science and Research (ESR). Research and reports published prior to this date may reference the organisation’s former name.

Summary

The Enteric Reference Laboratory (ERL) typed 697 STEC in 2023, a decrease of 84 from the prior year (613 in 2022). The most common serotypes of the 697 total isolates identified were O157:H7 (148, 21.2%) and O26:H11 (120, 17.2%) followed by O128:H2 (91,13.1%), O38:H26 (35, 5.0%), and O91:H14 (30, 4.3%). Although O157:H7 and O26:H11 remained the most common serotypes identified, the percentage of O157:H7 dropped from 34.1% in 2022 to 21.2% in 2023 while O26:H11 increased from 14.0% to 17.2%. Where subtyping of the stx gene was successful, 95/148 (64.2%) O157:H7 and 49/120 (40.8%) O26:H11 isolates were stx2a positive. This is a reduction from 2022 where 78.0% of O157:H7 and 55.7% of O26:H11 subtyped were positive for stx2a. The stx2a subtype was commonly detected in cases with haemolytic uremic syndrome (HUS) (11/13 cases, 84.6%) in New Zealand. Additionally, 12/13 cases with HUS with a typed isolate were either O157:H7 (1 stx2c and the rest stx2a) or O26:H11 (all stx2a) with the remaining case being an O104:H7 (stx1c present).

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