Editing Diphtheria (section)

==Diagnosis==
The current [[clinical case definition]] of diphtheria used by the [[United States]]' [[Centers for Disease Control and Prevention]] <!-- (CDC) --> is based on both laboratory and clinical criteria.

===Laboratory criteria===
* Isolation of ''C.&nbsp;diphtheriae'' from a Gram stain or throat culture from a clinical specimen.<ref name="MedlinePlusEncyclopedia Diphtheria"/>
* Histopathologic diagnosis of diphtheria by Albert's stain.

===Toxin demonstration===
* In vivo tests (guinea pig inoculation): Subcutaneous and intracutaneous tests.{{citation needed|date=March 2023}}
* In vitro test: Elek's gel precipitation test, detection of tox gene by PCR, ELISA, ICA.

===Clinical criteria===
* Upper respiratory tract illness with sore throat.
* Low-grade fever (above {{convert|39|C|F}} is rare).
* An adherent, dense, grey pseudomembrane covering the posterior aspect of the pharynx; in severe cases, it can extend to cover the entire tracheobronchial tree.

===Case classification===
* Probable: a clinically compatible case that is not laboratory-confirmed, and is not epidemiologically linked to a laboratory-confirmed case.
* Confirmed: a clinically compatible case that is either laboratory-confirmed or epidemiologically linked to a laboratory-confirmed case.

Empirical treatment should generally be started in a patient in whom suspicion of diphtheria is high.