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Increased Prevalence and diversity of VTEC in Ireland: Fact of Artifact?

This study examines the increased prevalence and diversity of verocytotoxigenic E. coli (VTEC) in Ireland. It discusses the methods used for VTEC testing and the challenges in accurately detecting and identifying non-O157 VTEC strains. The study emphasizes the importance of communication between clinical and laboratory findings in order to effectively manage VTEC outbreaks.

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Increased Prevalence and diversity of VTEC in Ireland: Fact of Artifact?

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  1. Increased Prevalence and diversity of VTEC in Ireland: Fact of Artifact? Dr Anne Carroll Dr Eleanor McNamara HSE-PHL-Dublin

  2. PHL Scope • Official testing laboratory, Food and water (S.I. 85 of 1998 and S.I. 117 of 2010). • Accredited ISO 17025 • National VTEC diagnostic and typing service (Clinical, foods water environmental) • Clinical diagnostic general microbiology service, hospital/GP HSE-PHL-Dublin

  3. VTEC Reference Service • National VTEC Service • Stools, Food, Water. • Isolate Confirmation • Accredited • PCR >22,000 tests • PFGE HSE-PHL-Dublin

  4. VTEC incidence HSE-PHL-Dublin

  5. VTEC incidence HSE-PHL-Dublin

  6. HSE-PHL-Dublin

  7. 2011 VTEC serogroups 2011: 17 serogroups 15 clinical +2 food 2002-2011 33 serogroups + HSE-PHL-Dublin

  8. 2011 HPSC VTEC subgroup • HPSC • Ref lab • 5 labs • Public health • Consensus + recommend standardised methods for VTEC HSE-PHL-Dublin

  9. Risk HSE-PHL-Dublin

  10. Lab Methods US “all stools submitted for routine testing from patients be simultaneously cultured for O157 and tested with an assay that detects Shiga toxins to detect non-O157 STEC” “Specimens or enrichment broths in which Shiga toxin or STEC are detected but from which O157 STEC are not recovered should be forwarded as soon as possible to a state or local public health laboratory”. HSE-PHL-Dublin

  11. Lab Methods ROI HSE-PHL-Dublin

  12. Lab 1 HSE-PHL-Dublin

  13. Lab 1 2012 HSE-PHL-Dublin

  14. Pre 2012 samples referred to ref lab based on risk and not lab findings (stools). HSE-PHL-Dublin

  15. Lab 7 HSE-PHL-Dublin

  16. Lab 7 STEC CHROMagar HSE-PHL-Dublin

  17. Pre 2012 samples referred to ref lab primarily based on lab findings and not risk (Isolates) HSE-PHL-Dublin

  18. Lab 2 No changes to methods HSE-PHL-Dublin

  19. samples referred to ref lab based on both lab findings and risk (stools and isolates) HSE-PHL-Dublin

  20. Issues • PCR Direct from stool • PCR pos culture negative issue • Direct detection of vt1 or vt2 gene(s) (without strain isolation), probable or confirmed depending on clinical criteria (HPSC) HSE-PHL-Dublin

  21. Issues • Ref lab • Direct PCR, Enrichment/IMS PCR, colony confirmation. • Direct PCR pos and/or Enrichment/IMS PCR pos + colony confirmed • Direct PCR pos + Enrichment/IMS PCR pos but can’t isolate colony • Direct PCR pos + Enrichment/IMS PCR neg • Do 2 +3 have the same PH implications? HSE-PHL-Dublin

  22. Direct PCR pos + Enrichment/IMS PCR pos but can’t isolate colony • Organism seems to be growing viable • Shedding of viable organism possible PH risk • Source of infection HSE-PHL-Dublin

  23. Direct PCR pos + Enrichment/IMS PCR neg • Organism not growing not viable • Shedding of non viable organism not a PH risk • May have been infection with organism subsequently dying source of infection • May have been no infection but ingestion of non viable organism e.g. from treated water or processed food HSE-PHL-Dublin

  24. If Use PCR only result (2 or 3) may not be true result • O26 vt2 PCR pos • O26 vt2 • O26 vt neg + other serogroup vt2 pos • O26 vt2 + other serogroup vt2 pos HSE-PHL-Dublin

  25. Challenges • Methods • Risk • Transport • Facilities • IT HSE-PHL-Dublin

  26. Summary •  VTEC in recent years • Particularly in non-O157 VTEC • Introduction of mandatory notification • Increased awareness non-O157 VTEC • Recent increases of non-O157 VTEC can be attributed to more targeted methods • Challenges • Clinical and lab findings need to be taken together • Lab + PH need to communicate HSE-PHL-Dublin

  27. Thank You Thank you to dedicated PHL Staff HSE-PHL-Dublin

  28. VTEC Reference Service Outbreak Service • Primary High Risk sample analysis • Confirmation and Typing • Medical advisory service • OCT • Data collation HSE-PHL-Dublin

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