Hey, Good to see you here 😀 …… In this Article, we’re gonna discuss in detail about various biochemical tests of Corynebacterium diphtheriae….. If you have any queries, don’t forget to mention in Comments…Thanks
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
⇒ 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.
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:
TESTS RESULTS
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.
The other sugar fermentation tests which are described below are of great importance in research work.
SUGARS RESULTS
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)
Galactose VARIABLE
(As Per The Strain)
Raffinose VARIABLE
(As Per The Strain)
Starch VARIABLE
(As Per The Strain)
Sucrose VARIABLE
(As Per The Strain)
That’s all about the Biochemical tests for Corynebacterium diphtheriae
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