Editing Corynebacterium diphtheriae (section)

==Identification==
To identify ''C. diphtheriae'', a [[Gram stain]] is performed to show [[Gram-positive]], highly [[pleomorphism (microbiology)|pleomorphic]] organisms often looking like Chinese letters. Stains such as [[Albert's stain]] and [[Ponder's stain]] are used to demonstrate the [[metachromasy|metachromatic]]  [[Granule (cell biology)|granules]] formed in the polar regions. The granules are called polar granules, or [[volutin granules]], known under the eponymous name Babes-Ernst granules after their inventors [[Paul Ernst (pathologist)|Paul Ernst]] and [[Victor Babeș|Victor Babes]]. An enrichment medium, such as [[Löffler's medium]], preferentially grows ''C. diphtheriae''. After that, a differential plate known as [[Hoyle's agar|tellurite agar]], allows all ''Corynebacteria'' (including ''C. diphtheriae'') to reduce tellurite to metallic tellurium. The tellurite reduction is colourimetrically indicated by brown colonies for most ''Corynebacterium'' species or by a black halo around the ''C. diphtheriae'' colonies. The organism produces [[catalase]] but not [[urease]], which differentiates it from ''[[Corynebacterium ulcerans]]''. ''C. diphtheriae'' does not produce [[pyrazinamidase]] which differentiates from ''[[Corynebacterium striatum]]'' and ''[[Corynebacterium jeikeium]]''.<ref>{{cite web|url=https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/371490/ID_2i4.1.pdf|title=UK Standards for Microbiology Investigations – Identification of Corynebacterium species|date=12 December 2023 }}</ref>