Diphtheria Culture

Code:
DIPH CULT

Sample Type:

Throat or nasopharyngeal swab on Amies Agar Gel Transport Swab (Blue top)

Send to laboratory as quickly as possible. If delays likely, refrigerate at 2 to 10 °C

Ref Ranges/Units:

N/A

Turnaround:

Referred test – 7-10 days

Special Precautions/Comments:

N.B. Please ensure the patient meets one (or more) of the following criteria and provide appropriate clinical detail:

  • Membranous or pseudomembranous pharyngitis/tonsillitis
  • Contact with a confirmed case within the last 10 days
  • Travel abroad to high risk area within the last 10 days (including South-East Asia, South America, Africa and India)
  • Contact with someone who has been to a high risk area within the last 10 days
  • Contact with any animals (including household pets, visiting a farm or petting zoo) within the last 10 days
  • Recent consumption of any type of unpasteurised milk or dairy products
  • The patient works in a clinical microbiology laboratory, or similar occupation, where Corynebacterium species may be handled.

Interferences:  Antibiotics may affect growth of certain bacteria.

Method:  Samples where diphtheria (Corynebacterium diphtheriae) is suspected will receive routine culture at The Pathology Centre (please refer to Throat Swab (C&S)) then referred to Freeman Hospital for C. diphtheriae selective culture. Calibration: N/A.  EQA scheme: NEQAS EQA scheme. IQC: N/A.

Interpretation: Negative cultures will be reported as Culture for Corynebacterium diphtheria negative. The Consultant Microbiologist will be notified of positive cultures and clinical comment provided as necessary.

Additional Information:

Background information: Diphtheria is an acute infectious disease of the upper respiratory tract and occasionally the skin. It is caused by toxigenic strains of Corynebacterium diphtheriae, of which there are 4 biotypes, (gravis, mitis, intermedius and belfanti), Corynebacterium ulcerans and Corynebacterium pseudotuberculosis.

All can carry the phage-borne diphtheria toxin gene. In a fully developed case of diphtheria, this toxin damages the pharyngeal epithelium to produce a leathery membrane, giving the disease its name. This membrane may occlude the airway, sometimes causing death by respiratory obstruction. Systemic absorption of the toxin may also cause damage to the heart and nervous system, causing or contributing to disability or death.

The usual site of carriage or infection is the throat or nasopharynx, occasionally the nose.

Keywords: Diphtheria, throat, pharyngitis, tonsillitis, travel abroad, animal contact, unpasteurised milk unpasteurised dairy
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