Listeria monocytogenes – Confirmation and Whole Genome Sequencing

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

Specimen Collection and Handling

Specimen Requirements

Test Requested Required Requisition(s) Specimen Type Minimum Volume Collection Kit

Listeria monocytogenes

Pure viable subculture of organism (eg Blood Agar)

Listeria monocytogenes

A swab of the pure subculture in Amies transport medium

Submission and Collection Notes


Submit subculture of an organism on an appropriate medium that supports the growth (e.g. Blood Agar). Swab of pure culture in bacterial transport medium is an acceptable alternative.


If a swab is received the turn-around time will be delayed by at least 24 hours.


Primary cultures are unacceptable as they should be processed in the originating laboratory. The submitter will be contacted by telephone. A report will be issued to indicate that the test has been rejected.


Complete all fields of the Reference Bacteriology Requisition, including:

  • test(s) requested
  • culture information
  • clinical/epidemiology
  • contact information

Storage and Transport

Place specimen into a biohazard bag and seal. Label the specimen with 2 unique identifiers prior to shipment. Specimen should be transferred to the laboratory within 48 hours of collection.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Listeria monocytogenes cultures are tested daily, Monday to Friday.

Turnaround time for test results is up to 4 days from receipt by PHO laboratory for identification/confirmation.

Test Methods

Listeria monocytogenes isolates are identified by conventional biochemicals. Isolates from all sites are forwarded to the Molecular Surveillance section at the PHO Laboratory Toronto for Whole Genome Sequencing for provincial surveillance and outbreak testing support.


Results are reported to the ordering physician or health care provider as indicated on the requisition.

Specimens that are positive for Listeria monocytogenes are to be reported to the Medical Officer of Health as per Health Protection and Promotion Act.


LAB-SD-043, Listeria monocytogenes – Clinical and Food Testing Guidelines for Foodborne Illness Outbreaks

LAB-SD-125, Reference Bacteriology and Antimicrobial Susceptibility: New Requisition and Testing Algorithm for Improved Test Utilization

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Updated 25 Sep 2019