Lab Test

C diphtheriae Culture

Corynebacterium diphtheriae Culture, Diphtheria

Test Codes

ARUP #60360, EPIC: LAB6613, SOFT: XCDC


Send Outs


Due to specimen stability, can only be collected Monday – Thursday only. For questions, call the Laboratory at 800-551-0488.

Specimen Collection Criteria

Collect: ONE of the following specimen types:

  • Throat or NP Swab: Swab the site of membrane or inflammation and place the swab in bacterial transport media. Please see the Specimen Collection Manual for Nasopharyngeal (NP) Swab Collection.
  • Wounds: Swab the base of a cleansed wound and place the swab in bacterial transport media.

Specimen source is required. Send specimen for processing immediately after collection at room temperature.

Physician Office/Draw Specimen Preparation

Do not refrigerate or freeze. Maintain specimen at room temperature (20-26°C or 68-78.8°F) prior to transport.

Preparation for Courier Transport

Transport: Swab in bacterial transport medium, at room temperature (20-26°C or 68-78.8°F).

Rejection Criteria

  • Outdated specimens.
  • Specimens from inappropriate sites.
  • Refrigerated or frozen specimens.
  • Specimens not collected and processed as indicated.

In-Lab Processing

Do not refrigerate or freeze. Maintain specimen at room temperature (20-26°C or 68-78.8°F) prior to transport.

Transport: Swab in bacterial transport medium, at room temperature (20-26°C or 68-78.8°F).


Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 48 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.


Sent to ARUP Laboratories, Salt Lake City, UT.


Sunday – Saturday.
Results available in 2-4 days.

Reference Range


Test Methodology

Culture / Identification.


Note: Demonstration of toxin production is necessary for a definite identification of pathogenic C. diphtheriae.

Specimens for culture should be obtained from the nasopharynx and throat and from any lesions. Material should be obtained from beneath the membrane, or a portion of the membrane itself should be submitted for culture. Because special media are required, the laboratory must be notified that C. diphtheriae is suspected. When C. diphtheriae is recovered, the isolate must be tested for toxigenicity at MDCH. (1)

Clinical Utility

This assay aids in the diagnosis of diphtheria.

Clinical Disease

Corynebacterium diphtheriae, an irregularly staining, Gram-positive, nonmotile, pleomorphic bacillus is the causative agent of diphtheria. Diphtheria usually occurs as membranous nasopharyngitis and /or obstructive laryngotracheitis. These local infections are associated with a low-grade fever and the gradual onset of manifestations during 1 to 2 days. Less commonly, the disease presents as cutaneous, vaginal, conjunctival, or otic infections. Cutaneous diphtheria is more common in tropical areas and among the homeless. Life-threatening complications of diphtheria include thrombocytopenia, myocarditis, and neurologic problems such as vocal cord paralysis and ascending paralysis similar to that of Guillain-Barre syndrome. (1)


Humans are the only known reservoir of C. diphtheriae. Sources of infection include discharges from the nose, throat, eye, and skin lesions of infected persons. Illness is most common in low socioeconomic groups living in crowded conditions. Infection can occur in immunized and partially immunized persons as well as in the unimmunized; disease is most common and most severe in unimmunized or inadequately immunized individuals. The incidence of disease is greatest in the fall and winter, but summer epidemics can occur in warmer climates in which skin infections are prevalent. Communicability in untreated persons usually lasts for 2 weeks or less, but occasionally it persists for several months. In patients treated with appropriate antibiotics, communicability usually lasts less than 4 days. Occasionally, chronic carriage occurs, even after antimicrobial therapy. (1)

Incubation Period

2 to 5 days but occasionally longer. (1)


Transmission results primarily from contact with a patient or carrier. Rarely, fomites can serve as vehicles of transmission, and food-borne outbreaks have occurred. (1)


  1. Chin, J. 2000. Control of Communicable Diseases Manual. 17th ed. APHA. Washington, D.C. pp. 165-170.
  2. Funke, G., Bernard, K.A. 2007. Manual of Clinical Microbiology, 9th edition. P.R. Murray et al.(eds.), ASM Press. Washington, D.C. pp. 491-509.

CPT Codes

87081 for presumtive identification. If definitive identification is required, add 87077.


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