DIPHTHERIA (CORYNEBACTERIUM DIPHTHERIAE)

Laboratory: Microbial Reference

Test Description: Culture and identification of Corynebacterium diphtheriae

Order Approval Required? Yes

Submitters must notify the Diagnostic Laboratory (804-648-4480 ext. 252) of suspected diphtheria at least 24 hours prior to specimen collection

Testing is not available on weekends or holidays

Specimen Type:

• Nasopharyngeal swab
• Swab of area beneath pseudomembrane (nose, tonsils, voicebox, and/or throat)
• If cutaneous diphtheria is suspected, collect skin aspirate/swab, throat swab, and nasopharyngeal swab

Collection Container: A routine swab collection system (such as an E-swab) containing transport medium such as Amies or Stuart's medium

Collection Guidelines: Swab from inflamed areas of nasopharynx. If pseudomembrane is present and can be removed, swab from beneth the membrane and collect from several areas to increase sensitivity. Nasopharyngeal swabs from suspected carriers may be collected. If cutaneous diphtheria is suspected, collect skin aspirate/swab, throat swab, and nasopharyngeal swab.

Storage Instructions:

• Store specimens at 2-30°C
• Specimen must be received within 24 hours of collection

Transportation Instructions:

• Transport: 2-30°C
• Specimen must be received within 24 hours of collection

Test Methodology: Microbiological culture and organism identification with MALDI-TOF and conventional techniques

Additional Information: If C. diphtheriae is identified from culture the isolate will be sent to the CDC for confirmation and toxigenicity testing

Causes for Rejection:

• Specimen not received within 24 hours of collection
• Sample lacks two patient identifiers or mismatached samples and test request forms
• Incorrect transport media
• Broken transport media
• Specimens not representative of the anatomic site from which C. diphtheriae is commonly found
• True duplicate specimens (same collection date, source, and patient identifiers) may be rejected
• Specimen received out of the appropriate temperature range.