Corynebacterium diphtheriae Isolation from Clinical Specimen

Laboratory Fee Schedule
Procedure Number: MAA0023A

Synonym(s): Diphtheria screen, toxin, lymph nodes
Requisition Form G-2B.
Test Description Isolation of Corynebacterium diphtheriae from clinical specimens with reflex to identification and toxin testing (CDC reference testing).  
Pre-Approval Needed N/A
Supplemental Information Required N/A
Supplemental Form(s) N/A

Performed on Specimens from (sources)




Sample/Specimen Type for Testing Throat, nasal, or wound swab.  
Minimum Volume/Size Required Single swab.
Storage/Preservation Prior to Shipping
  • Collect specimen from patient and immediately place swab in Amies, Stuart’s or Loeffler’s transport media.
  • If membranes are present and can be removed, swab from beneath the membrane. 
  • Store refrigerated at 2–8°C until shipment.  
  • Ship within 24–48 hours of collection. 
Transport Medium
  • Amies, Stuart’s or Loeffler’s transport medium.
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 to Laboratory. 
  • 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-contained 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 Culture
Turn-around Time 3–5 days. 
  • Specimen should be taken from patient prior to antimicrobial therapy. 
Common Causes for Rejection
  • Incorrect specimen collection or submission methods 
  • Mismatch(es) between patient identifiers on G-2B submission form and specimen label.
  • Insufficient specimen growth
  • Incorrect storage conditions
  • Expired reagents/media/collection container
  • Discrepancies between G-2B submission form and specimen label
  • Missing/incomplete/illegible submission form
  • Specimens not representative of the anatomic site from which C. diphtheriae is commonly found. 
Additional Information
  • If C. diphtheria is isolated and identified, it will be submitted to CDC for toxin testing. 
  • If no C. diphtheria is isolated, the clinical specimens are also routinely screened for Streptococcus pyogenes