Biochemical tests for Corynebacterium diphtheriae (C. diphtheriae)

BIOCHEMICAL TESTS FOR CORYNEBACTERIUM DIPHTHERIAE (C. DIPHTHERIAE)

In this Article, I’m gonna discuss various biochemical reactions for the well known causative agent of Diphtheria & Cutaneous infections i.e. the Corynebacterium diphtheriae abbreviated as C. diphtheriae.

However, only a few reactions are most commonly used and medically important for distinguishing pathogenic strains of Corynebacterium diphtheriae from other non- pathogenic strains as well as from other species of Corynebacterium which are as follows:



Catalase Positive

Indole Negative

Citrate Negative

Urease Negative

Methyl red (MR) Positive

Voges – Proskauer (VP) Negative

biochemical tests for corynebacterium diphtheriae - mr positive - vp negative - citrate negative - indole negative
VARIOUS BIOCHEMICAL TESTS FOR CORYNEBACTERIUM DIPHTHERIAE

Blackish–brown colonies with a brownish halo around the colonies on Tinsdale agar medium

Greyish black colonies with weak b-hemolysis or γ-hemolysis on Tellurite blood agar medium.

Check out the Morphology & Culture Characteristics of Corynebacterium diphtheriae

Besides that of various biochemical reactions and Sugar fermentation tests, certain enzymatic reactions are also medically important to distinguish Corynebacterium diphtheriae from other Corynebacterium sp.

Below is the list of these Enzymatic Reactions and various other biochemical tests for Corynebacterium diphtheriae which have great importance in research and for knowledge but are not routinely employed:

TESTSRESULTS
Catalase+VE (POSITIVE)
H2S Production+VE (POSITIVE)
Methyl Red+VE (POSITIVE)
Nitrate Reduction+VE (POSITIVE)
Tellurite Reduction+VE (POSITIVE)
Alkaline Phosphatase-VE (NEGATIVE)
CAMP Test-VE (NEGATIVE)
Citrate-VE (NEGATIVE)
Coagulase-VE (NEGATIVE)
Esculinase-VE (NEGATIVE)
Indole-VE (NEGATIVE)
Oxidase-VE (NEGATIVE)
Ornithine decarboxylase-VE (NEGATIVE)
Tyrosine Hydrolysis-VE (NEGATIVE)
Urease-VE (NEGATIVE)
VP (Voges Proskauer)-VE (NEGATIVE)

Corynebacterium diphtheriae ferments various sugars producing acid without Gas production.

But these sugar fermentation tests are of no diagnostic value in routine laboratory tests except Lactose & Mannitol fermentation test, which is of great importance in differentiating Corynebacterium diphtheriae, which is unable to ferment Lactose and mannitol, from other Pathogenic & non-pathogenic Corynebacterium species.

Check out the Biochemical tests for Salmonella typhi

The other sugar fermentation tests which are described below are of great importance in research work.

SUGARSRESULTS
Arabinose+VE (POSITIVE)
Dextrose+VE (POSITIVE)
Fructose+VE (POSITIVE)
Glucose+VE (POSITIVE)
Maltose+VE (POSITIVE)
Mannose+VE (POSITIVE)
Dulcitol-VE (NEGATIVE)
Lactose-VE (NEGATIVE)
Mannitol-VE (NEGATIVE)
Salicin-VE (NEGATIVE)
Trehalose-VE (NEGATIVE)
Xylose-VE (NEGATIVE)
GalactoseVARIABLE
(As Per The Strain)
RaffinoseVARIABLE
(As Per The Strain)
StarchVARIABLE
(As Per The Strain)
SucroseVARIABLE
(As Per The Strain)


That’s all about the Biochemical tests for Corynebacterium diphtheriae



Further Reading:

Corynebacterium diphtheriae: Diphtheria – Microrao

Rapid Microbiochemical Identification of Corynebacterium diphtheriae – Journal of Clinical microbiology

Identification of Corynebacterium species – Society for Applied Microbiology

SAHIL BATRA

Hi, I'm the Founder and Developer of Paramedics World, a blog truly devoted to Paramedics. I am a Medical Lab Tech, a Web Developer and Bibliophiliac. My greatest hobby is to teach and motivate other peoples to do whatever they wanna do in life.

You May Also Like

Leave a Reply

Your email address will not be published. Required fields are marked *