Diphtheria Toxin Testing Service

This service consists of the molecular detection of the Diphtheria Toxin (DT) tox gene and phenotypic detection of expressed diphtheria toxin by the modified Elek test.

Pure cultures of Corynebacterium diphtheriae.

Slants or plates of any suitable media and swabs in transport media are all acceptable. Slants preferred.

Store samples between room temperature and 37^oC until shipped for testing. Ship at room temperature.

Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.

Suspected diphtheria case with symptoms for respiratory diphtheria, throat diphtheria, cutaneous diphtheria, endocarditis, pharyngitis, and lymphadenitis.

Completed Special Bacteriology requisition form detailing all patient information and relevant clinical information. If possible, attach lab results that have already been done at local or provincial laboratories.

All patient and strain history must be included. Detection in clinical material available upon special request only - please contact the Special Bacteriology laboratory for approval before sending specimens.

Molecular detection of DT tox gene is done by the conventional PCR detection of Fragment A and the entire DT tox gene. Phenotypic detection for the gene ex pression is done by the modified Elek test. Positive PCR results must be confirmed by a positive modified Elek test. Strains with a positive PCR result but Elek negative (gene present but not expressed) are considered non-toxigenic ¹.

18 calendar days. In cases where staff or resources are limited final report may be delayed and status of request will be forwarded in a preliminary report. Final report will be sent once all results from the molecular and phenotypic detection of diphtheria toxin as well as all other relevant tests are complete.

1. Efstratiou, A., KH Engler, CS Dawes, and D Sesardic. 1998. Comparision of Phenotypic and Genotypic Methods for Detection of Diphtheria Toxin among Isolates of Pathogenic Corynebacteria. J Clin Microbiol. 36(11): 3173-3177.
2. Efstratiou, A, and RC George. 1999. Laboratory guidelines for the diagnosis of infections caused by Corynebacterium diphtheriae and C. ulcerans. Communicable Disease and Public Health 2(4):250-257.
3. Public Health Agency of Canada. 2009. Case description for Communicable Diseases under National Surveillance-Diphtheria. CCDR supple. Vol 35S2. Pg 63-64.
4. CDC Atlanta. Insert brochure for catalogue no. BS0629 C. diphtheriae reference antitoxin for use in toxigenicity test. NOTE that description is consistent with the classic, not Modified ELEK test.
5. Engler, K. H., T. Glushkevick, I. K. Mazurova et al. 1997. A modified ELEK test for detection of toxigenic Corynebacteria in the diagnostic laboratory. J. Clin. Microbiol. 35:495-498.
6. Funke, G. and K. A. Bernard. 2011. Coryneform Gram-Positive rods. In Manual of Clin. Microbiol 10th ed. ASM publications, Washington DC. Pg 413-442.