Summary

Verocytotoxin-producing E.coli (VTEC/STEC) confirmed by ERL in 2018. STEC/VTEC confirmations continue to increase as another two laboratories commenced culture independent testing for this organism in January and November 2018. Thus, more than 75% of clinical samples in New Zealand are now being screened routinely for stx genes. The ongoing increase in non-O157 STEC cases in NZ is due to changes in detection methods. STEC O157 case numbers have remained relatively stable over this time. See Appendix B. The 10 most common STEC O types confirmed in 2018 were: O157, O26, O128, O146, O38, O123/186, O103, O174, O176, and O91. Note: the USA "Top 7" serotypes only include O157, O26 and O103 from NZ's top 10. However, some of NZ's common types are being regularly seen elsewhere in the world. stx2+ STEC O26 continues to emerge as a significant pathotype with 15 isolates confirmed in 2018. The number of samples from which an organism has not been able to be isolated is similar to 2017, and comprehensive typing is not currently possible without a pure culture isolate. Work to improve organism isolation is ongoing and the upcoming introduction of routine WGS will add to our understanding of this group of organisms.