Toxin and Virulence Gene Detection

Identification of shiga toxins (STX) and other virulence factors from suspected Escherichia coli and Shigella spp. samples.

Isolate (pure culture) from urine, stool, blood, environmental, food, other.

Isolate provided on appropriate culture medium with visible growth. Samples can also be submitted under frozen conditions provided they are shipped in appropriate media to survive transport.

Send as growth on appropriate culture medium or in appropriate transport medium. Frozen samples should be shipped on dry ice or other method to ensure they remain frozen.

Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult eitherPart 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.

Gastroenteritis, septicemia, infection, other.

Completed Enteric Diseases requisition form.

N/A

Accredited testing:

PCR-based assays targeting:

• shiga toxin genes (stx1 and stx2)
  • stx2 gene subtyping (currently for subtypes stx2a to stx2g)
• commonly associated virulence factors:
  • eaeA, ehxA (For E. coli samples)
  • ipaH, ial (For Shigella samples)
    

Non-accredited testing:

In-silico tools for detection of E. coli toxins and stx2 subtyping are available for samples that cannot be determined by accredited PCR-based assays and may be used on a case-by-case basis.

For clinical diagnostic or outbreak samples*: 14 calendar days.

For surveillance or research samples*: 3 months

*Please indicate on requisition if identification is for i) clinical diagnostic or outbreak OR ii) surveillance or research application.

Please note that for poor or slower growing organisms reporting of results may be delayed beyond listed turnaround times.

1. Paton, A.W. and Paton, J. C. 1997. Detection and Characterization of Shiga Toxigenic Escherichia coli by using Multiplex PCR Assays for stx1, stx2, eaeA, Enterohemorrhagic E.coli hlyA, rfb0111, and rfb0157. J. of Clin. Micro. 36: 598 – 602.

2. Sethabutr, O. et al. 1993. Detection of Shigellae and Enteroinvasive Escherichia coli by Amplification of the Invasion Plasmid Antigen H DNA Sequence in Patients with Dysentery. J. of Infect. Dis. Jan 167; 458-461.