Test Methodology

Phenotypic (traditional) agglutination-based serogrouping ; limited biochemical testing to confirm purity and MALDI-TOF for identification, if needed​​.​

Reflex Testing Criteria

Salmonella isolates are routed for molecular characterization using Whole Genome Sequencing (WGS) for public health surveillance and epidemiologic investigations only (clinical reports are not issued).​

​Salmonella isolates that are presumptive S. Typhi or S. Paratyphi based on submitter results will be routed to traditional (phenotypic) serotyping. 

​Salmonella isolates from sterile sources (e.g. blood) that do not have serogroup information available, or are Serogroup A or Serogroup D (with no indication as not S. Typhi) will be screened internally with limited biochemicals. Presumptive typhoidal isolates will be routed for traditional serotyping.

Pre-Approval Required

Approvals only to CA local city/county public health labs and approved clinical reference laboratories

Supplemental Information and Required Form(s)

​​​Use MDL Lab Web Portal for ordering the test, select Test Requisition for Bacterial Culture for Identification – Form 446 “Bacterial Culture for Identification.”​ Barcode submittal form (PDF) is currently not available for ordering this assay. Please contact the laboratory if experiencing difficulties submitting the order. 

​Please include submitter’s test results on the submittal form.

As of October 1, 2024, traditional Salmonella serotyping has been discontinued for routine testing regardless of the source. Please select “Salmonella Confirmation and Serotyping” on the test requistion form for isolates that have been identified as Salmonella and have already been serogroup. These isolates will be routed for surveillance testing only, with results reported to local health departments via CalREDIE.

Required Specimen Type(s)

Pure Salmonella isolates only

Isolates should be subcultured prior to submission on nonselective nutrient agar (e.g., trypticase soy or heart infusion slant) in tube with leak-proof screw cap closure.

Contaminated cultures may be rejected.​

Minimum Volume Required

Viable growth should be present on the submitted subculture.

Specimen Stability

Store isolates at ambient or refrigerated temperature to maintain viability.

Rejection Criteria

• Submissions with insufficient or conflicting labelling 
• Leaking samples 
• Isolates that are non-viable upon subculture for testing
  
• ​Mixed/contaminated cultures

Storage/Transport Conditions

Grow fresh subculture under appropriate conditions on nonselective nutrient agar slant and verify purity prior to shipping. 

Isolates may be stored at ambient or refrigerated temperatures prior to shipping​.

Ship at ambient temperature or on cold packs; do not freeze or send frozen cultures.

Transport Medium, if applicable

Not applicable

Specimen Labeling

Two identifiers, including patient full name, and at least one other identifier (specimen accession number, date of birth, medical record number).

Shipping Instructions and Specimen Handling Requirements

Ship isolates at ambient temperature or with cold packs; do not freeze.

Follow the appropriate DOT/IATA approved shipping procedures.

Ensure that culture isolates are sent in tubes containing a screw-top cap that is additionally sealed with parafilm or tape for additional protection against leaking. DO N​OT send plated culture.​​

Ship to: 

Turnaround Time

30 calendar days

Interferences & Limitations

Unable to perform testing if the submitted culture is overgrown by bacterial and/or fungal contaminants or if the culture is non-viable.​
Reference Range

Not applicable

Additional Information

None

MDL Point of Contact

For questions regarding submissions, please email MDL.Submissions@cdph.ca.gov​ or call the MDL Immunodiagnostics laboratory at 510-412-3913​​​​