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Home › Products & Services › Infectious Diseases › Laboratories and Reference Facilities › Respiratory and Systemic Infection Laboratory (RSIL) ›Streptococcus and Diphtheria Reference Unit ›  Identification and toxigenicity testing of Corynebacterium diphtheriae and other potentially toxigenic Corynebacteria ( C. ulcerans and C. pseudotuberculosis)
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Identification and toxigenicity testing of Corynebacterium diphtheriae and other potentially toxigenic Corynebacteria ( C. ulcerans and C. pseudotuberculosis)

This service is available 24 hours a day, seven days a week. For advice on laboratory diagnosis of diphtheria and/or submission of samples to CfI during normal working hours contact Dr Androulla Efstratiou on 020 8327 7270, or Miss Gina Mann on 020 8327 7289. Out of hours and weekends, advice and service is available via the CfI main switchboard operator/vodafone answering service (Tel. 020 8200 4400) who will access the on-call staff by mobile telephone.

  • Cultures should be submitted to the laboratory by courier (if deemed urgent), and only after establishing contact with SDRU to inform them that a culture is on its way.
  • Advice on immunisation against diphtheria, provision of vaccine and provision of diphtheria antitoxin for therapeutic use is available from the Immunisation, Hepatitis and Blood Safety Department of HPA-Colindale, on 020 8200 6868 (Dr. M. Ramsay, 020 8200 7085 or Joanne White 020 8327 7446) during normal hours. Out of hours via HPA-Colindale Duty Doctors on 020 8200 4400.
  • Toxigenic C.diphtheriae is very uncommon within the UK and is almost always imported. A travel and immunisation history should always be obtained from suspected cases of diphtheria and, if feasible, their close contacts.
  • Some strains of C.ulcerans (and very rarely C.pseudotuberculosis) may produce diphtheria toxin and the illness caused may present as clinical diphtheria. Such infections should be treated as diphtheria with the important proviso that person-to-person transmission is extremely rare. Infection is usually acquired from raw milk and/or contact with farms and farm animals and also close contact with companion animals.
  • UK microbiological laboratories are encouraged to submit all isolates of C.diphtheriae and other potentially toxigenic corynebacteria to CPHL for surveillance and monitoring purposes. The unit is a designated WHO Collaborating Centre for reference and research on diphtheria.

Turnaround time: Turnaround times vary according to the degree of clinical and public health urgency. If the situation warrants it, a rapid result for the detection of diphtheria toxin can be issued within 24 hours of receipt of a pure culture. All results are communicated by telephone. Under normal circumstances, a final written report is issued within 5 days of receipt and all interim results are given by telephone usually within 24h.

Isolates that are cystinase negative may be referred to the Laboratory of HealthCare Associated Infections (LHCAI) for full identification. The turnaround time in this instant will vary.

How to obtain service

Use the R3 Streptococcus & diphtheria referral form (PDF, 349 KB) and supply pure culture on blood or Loeffler slopes.

NB. Do not delay submission if you do not have the requisite forms or slopes. Specimen submissions regarded by the sending laboratory as urgent should always be notified to SDRU by telephone as described above.

Other information: PCR for detection of the diphtheria toxin gene is not undertaken routinely. The gold standard test for detection of toxigenicity is the phenotypic Elek test which is the key test used by the reference unit. PCR can be undertaken but only in urgent circumstances and only after discussion with the Unit Head (Dr Efstratiou). The definitive and final result is always based upon the Elek phenotypic test.


Last reviewed: 24 February 2012