Diphtheria Diagnosis

NewsGuard 100/100 Score

Diphtheria is usually diagnosed based on a patient’s clinical presentation. Presumptive treatment is then started while further tests to confirm the diagnosis are performed. The criteria for diagnosing this infection are outlined by the Centers for Disease Control and Prevention (CDC) and include both clinical and laboratory criteria.

The steps taken to diagnose diphtheria are outlined below:

In suspected cases of diphtheria it is important to start therapy as soon as possible, so presumptive therapy is usually started while further tests are arranged.

The diagnosis can be confirmed by culturing a swab sample from infected areas. A swab is taken from the throat, and in particular from the tonsillar crypts as well as any discolored or ulcerated areas.

The infected sample material is incubated in a nutrition medium. The preferred medium for diphtheria is one that contains tellurite, which gives the organism a selective growth advantage. A blood agar plate may also be used to check for the presence of other bacteria such as hemo¬lytic streptococcus.

If diphtheria is detected, the bacilli are checked to see if they are producing toxins.

A sample of the grey-white membrane that forms in the throat can be subjected to Gram staining in which gram-positive bacteria retain the dye after being washed with alcohol. On Gram staining, diphtheria bacilli appear as rod-shaped cells in a beaded arrangement.

To detect the infection among carriers or non-symptomatic diphtheria cases, material from a throat swab can be cultured using Löffler or Pai slant. After 18 to 24 hours of incubation, a medium containing tellurite is inoculated with growth from the slant.

CDC diagnosis criteria

According to the CDC, the following clinical and laboratory criteria need to be met for a diagnosis of diphtheria to be confirmed:

Clinical criteria

  • Presence of upper respiratory tract infection along with sore throat
  • Presence of high fever
  • Presence of the grey white membrane or pseudomembrane over the throat, back of the mouth or tonsils

Laboratory criteria

  • Presence of corynebacterium diphtheriae in the throat swab samples
  • Histological or cellular level presence of the bacteria

Further Reading

Last Updated: Feb 26, 2019

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Mandal, Ananya. (2019, February 26). Diphtheria Diagnosis. News-Medical. Retrieved on May 28, 2024 from https://www.news-medical.net/health/Diphtheria-Diagnosis.aspx.

  • MLA

    Mandal, Ananya. "Diphtheria Diagnosis". News-Medical. 28 May 2024. <https://www.news-medical.net/health/Diphtheria-Diagnosis.aspx>.

  • Chicago

    Mandal, Ananya. "Diphtheria Diagnosis". News-Medical. https://www.news-medical.net/health/Diphtheria-Diagnosis.aspx. (accessed May 28, 2024).

  • Harvard

    Mandal, Ananya. 2019. Diphtheria Diagnosis. News-Medical, viewed 28 May 2024, https://www.news-medical.net/health/Diphtheria-Diagnosis.aspx.

Comments

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment
Post

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.

You might also like...
Bio Farma's Bio-TCV typhoid conjugate vaccine licensed in Indonesia following marketing approval