Description of the test
Culture is essential for the confirmation of the diphtheria diagnosis. Sample collection should occur as soon as possible upon suspicion of diphtheria, preferably before the start of antibiotic therapy, but also if it has already been administered.
Purpose of the test
Confirmation of diagnosis.
Criteria for performing this test in the context of reference activities
On suspicion of diphtheria. The diagnosis is mainly clinical. The pseudomembrane usually appears first around the tonsils and the rear-end of the pharynx, after which it spreads upwards towards palate and nasopharynx, and downwards towards the larynx and trachea. Atypical forms, starting at the nose or larynx, also exist.
Corynebacterium diphtheriae can also be isolated from skin lesions.
Detection of carriership of Corynebacterium diphtheriae in the frame of contact tracing around index patient.
Instructions for samples
Sample collection:
In case of respiratory diphtheria, use swab for collection from nose and throat, and from membranes if present. Several swabs should preferably be taken for suspect cases. This improves the chances of isolation and hastens the laboratory diagnosis. If possible, the sample should be taken from under the membrane, where the bacteria are most concentrated.
Skin lesion swabs.
Throat swabs for contact screening.
Storage conditions: transport the sample to the laboratory as quickly as possible.
Instructions for transport
- Transport conditions: room temperature, <24 hours.
- Specifications of transport medium: swab in gel medium (Amies) or eSwab.
The NRC does not provide sampling material.
Unacceptable requests
In the following circumstances samples are not accepted for culture:
- Dry swabs without transport medium
- Swabs in UTM medium
Turnaround time (and frequency of analysis)
Samples are put into culture upon arrival at the laboratory. Please alert the laboratory beforehand should the sample be expected to arrive after 18:00 (in order to inform the night shift).
Median TAT: 1 day, max. 3 days for a preliminary result.
Reporting of test results
- By telephone, secured electronic mail and postal services in case of a positive result.
- By postal services in case of a negative result.