Hey, Good to see you here 😀 …… In this Article, we’re gonna discuss in detail about various biochemical tests of Salmonella typhi….. 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 Enteric fever, Septicemia & Gastroenteritis i.e. the Salmonella typhi abbreviated as S. typhi.

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

[wp-svg-icons icon=”point-right” wrap=”i”] Produces H2S

[wp-svg-icons icon=”point-right” wrap=”i”] Indole Negative

[wp-svg-icons icon=”point-right” wrap=”i”] Citrate Positive

[wp-svg-icons icon=”point-right” wrap=”i”] Urease Negative

[wp-svg-icons icon=”point-right” wrap=”i”] Methyl red (MR) Positive

[wp-svg-icons icon=”point-right” wrap=”i”] Voges – Proskauer (VP) Negative

[wp-svg-icons icon=”point-right” wrap=”i”] Colorless – NLF colonies on MacConkey agar medium

[wp-svg-icons icon=”point-right” wrap=”i”] Jet black colonies with a metallic sheen on Wilson & Blair bismuth sulfite medium

[wp-svg-icons icon=”point-right” wrap=”i”] Pink or Red Colonies with black center on XLD medium.

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

Here is the list of these Enzymatic Reactions and various other biochemical tests for Salmonella typhi which have great importance in research and for knowledge but are not routinely employed in Pathology Laboratories:

[table id=105/]

Salmonella typhi ferments various sugars producing acid only as S. typhi is anaerogenic bacteria making it easy to differentiate from other species of Salmonellawhich ferment sugars producing acid with gas.

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

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

[table id=106/]

That’s all about the various Biochemical tests for Salmonella typhi (S. typhi).

Frequently Asked Questions (FAQs)

Biochemical tests are used to identify Salmonella, and these include tests for citrate utilization, hydrogen sulfide production, urease activity, and glucose fermentation.

The laboratory test for Salmonella involves culturing a sample from the patient on selective media, such as Salmonella-Shigella agar, and then performing biochemical tests to confirm the identity of the bacterium.

Biochemical tests for Salmonella Paratyphi are similar to those for other Salmonella species, including tests for citrate utilization, hydrogen sulfide production, and urease activity. Identification can be confirmed through serotyping, which involves identifying the specific antigens present on the bacterial cell surface.

Salmonella typhi is identified through culture and biochemical tests, which include tests for citrate utilization, hydrogen sulfide production, and urease activity. Serotyping can also be performed to identify the specific antigenic makeup of the bacterial strain.

The Widal test is a serological test used to diagnose typhoid fever. It involves detecting the presence of antibodies against specific Salmonella typhi antigens in a patient’s blood sample.

The ELISA test is an immunological assay that can be used to detect the presence of antibodies against Salmonella typhi in a patient’s blood sample. It is a more sensitive and specific test than the Widal test for diagnosing typhoid fever.