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Escherichia coli shiga-toxin gene detection and serotyping

Registry Details

Area Health Science
Lab name Enteric Reference Laboratory
Lab location NCBID Wallaceville
Test name Escherichia coli shiga-toxin gene detection and serotyping
Organisms E. coli
Requested for surveillance yes
Notice required no
Routine turnaround time 10 days
Culture requirements Pure culture. Mixed cultures may be referred for toxin testing if VTEC infection is suspected and the case meets the criteria described under the Details section below.
Media requirements Nutrient agar slope for cultures
Pre-transport requirements Ambient temperature
Transport requirements Ambient temperature
Unacceptable sample types Mixed cultures will not be tested
How results reported If positive: E. coli serotype and toxin/virulence genes profile. If negative, the isolate will be reported as negative for verocytotoxin.
Referral link Form

Description

Please refer to this document for a recommended culture process for STEC for stx positive samples.

Details

Changes to STEC/VTEC reference laboratory testing at ESR's Enteric Reference Laboratory

Effective: 15 September 2017

ESR's Enteric Reference Laboratory (ERL) will no longer accept faecal broths or mixed cultures for STEC/VTEC reference testing. ERL will only perform serotyping (and further characterisation) on pure cultures of STEC/VTEC referred by diagnostic laboratories where stx genes have been detected or Shiga toxin/Verotoxin production demonstrated. Exceptions to this will include broths or mixed cultures from “high risk” cases meeting one or more of the following criteria:

  • hospital inpatients
  • children under 10 years of age
  • cases of HUS or TTP
  • bloody diarrhoea
  • suspected clusters of cases /outbreaks
  • history of overseas travel in preceding 14 days
  • individual cases where testing is specifically requested by the local medical officer of health
  • individual cases upon discussion with an ESR clinical microbiologist or ERL co-ordinator

We would like to emphasise the need for diagnostic laboratories to continue referring STEC/VTEC isolates to ERL for serotyping and further characterisation.

ERL can offer a storage service for PCR positive, culture negative faecal broths referred from diagnostic laboratories. Specimens will be stored for a period of 3 months at -80°C for subsequent testing if requested by the local public health unit or ESR health intelligence team.

Please email any questions or comments you may have to contact jackie.wright@esr.cri.nz