Listeria spp. Definitive Identification

Laboratory Fee Schedule
Procedure Number: MAA0054A, MAA0033A

Synonym(s): Listeriosis, Listeria monocytogenes
Requisition Form G-2B
Test Description Identification confirmation of Listeria isolates with reflex to Whole Genome Sequencing (WGS) if Listeria monocytogenes 
Pre-Approval Needed N/A
Supplemental Information Required N/A
Supplemental Form(s) N/A
Performed on Specimens from (sources) Human
Sample/Specimen Type for Testing Pure Listeria isolates from blood, CSF, amniotic fluid, tissue (biopsy/autopsy), placenta
Minimum Volume/Size Required At least one viable colony of pure isolate per plate/slant)
Storage/Preservation Prior to Shipping Store refrigerated at 2–8°C until shipment.  
Transport Medium Any medium that supports the growth of Listeria spp. (e.g., blood agar, Heart Infusion agar)
Specimen Labeling
  • At least two patient identifiers required on specimen (e.g., patient full name, date of birth, medical record number). 
  • Three patient identifiers are preferred. 
  • Patient identifiers on specimen label must exactly match identifiers on submission form. (e.g., abbreviated name on label and full name on form is not acceptable.)
  • Additional DSHS Laboratory specimen labeling guidelines available online here.
Shipping and Specimen Handling Requirements
  • Ship refrigerated at 2–8°C on cold packs for overnight delivery
  • Ship according to Dangerous Goods Regulations, IATA, and/or CFR 49.
  • Category B Biological Substance, UN3373 shipping requirements apply.
  • Handle as infectious agent using universal precautions. 
  • Triple-contain in accordance with federal shipping regulations. 
  • Submitters are responsible for packaging and shipping specimens according to regulatory requirements. 
  • Laboratory does not supply collection kits or shipping materials.
  • Additional DSHS Laboratory specimen shipping guidelines online here
Method MALDI-TOF (mass spectrometry), Culture
Turn-around Time 5–10 days. 
  • Specimen should be taken from patient prior to antimicrobial therapy. 
  • Organisms must be viable for culture studies. 
  • Improper storage or shipping temperatures limit organism recovery. 
Common Causes for Rejection
  • Incorrect specimen collection methods 
  • Mismatch(es) between patient identifiers on G-2B submission form and specimen label.
  • Insufficient specimen growth
  • Non-viable isolates
  • Mixed culture/contamination
  • Incorrect storage conditions 
  • Expired reagents/media/collection container
  • Missing/incomplete/illegible submission form
Additional Information
  • If L. monocytogenes is identified, the specimen will be reflexed to WGS.  
  • Listeriosis is a notifiable condition and L. monocytogenes isolates are REQUIRED to be submitted to DSHS Laboratory per Texas Administrative Code (TAC) chapter 97.  
  • Mark the “IDEAS” box for the payor source on the G-2B submission form.