All Notes

Salmonella Typhi: Introduction, Identification Features, Keynotes, and Salmonella Footages

Introduction of Salmonella Typhi

Salmonella Typhi is a member of the family, Enterobacteriaceae and it is a Gram-negative bacillus, non-sporing, non-encapsulated, aerobic, or facultative anaerobe of size 2 to 4 × 0.6 µm that causes enteric fever (typhoid fever) and food poisoning or gastroenteritis.

Fig. 1. Salmonella Typhi growth on MacConkey medium, 2. Gram-stained image, 3. biochemical tests in TSI, SIM, citrate, and urea agar, and 4. Salmonella Typhi (black) and Salmonella Paratyphi on XLD agar

Biochemical Tests of Salmonella Typhi

Basic FeaturesProperties
1. Gram StainingGram-Negative Rods (GNRs)
2. SporeNon-Sporing
3. CapsuleNegative
4. MotilityPositive
5. PigmentNegative
6. Growth in potassium cyanide (KCN) mediumNegative
7. Catalase testPositive
8. Oxidase testNegative
9. Nitrate reduction testPositive
10. MR (Methyl Red) testPositive
11. VP (Voges- Proskauer) assayNegative
12. OF (Oxidative-Fermentative) testFermentative/Facultative anaerobe
13. Gas Negative
14. H2S productionPositive
15. Indole formationNegative
16. Urease/ urea hydrolysis testNegative
17. Citrate/ citrate utilizationNegative
18. DNase testNegative
19. Glucose fermentationPositive
20. Maltose fermentationPositive
21. Lactose fermentationNegative
22. Sucrose fermentationNegative
23. Xylose fermentationPositive
24. Mannitol fermentationPositive
25. Acetate UtilizationNegative
26. ONPG (β-galactosidase)Negative
27. Phenylalanine Deaminase (PDA)/PPA TestNegative
28. Lipase testNegative
29. Esculin Hydrolysis testNegative
30. Lysine Decarboxylase TestPositive
31. Ornithine Decarboxylase TestNegative
32. Arginine Dihydrolase TestNegative
Table: Properties of Salmonella Typhi

Keynotes on Salmonella

  • The mode of transmission of S. Typhi is the faeco-oral route.
  • The infective dose of typhoid is 10 bacilli through ingestion.
  • Most strains of Salmonella are motile except Salmonella gallinarum and S. pullorum.
  • Antigens of Salmonella are o antigen (somatic),H antigen (flagellar), Vi antigen and K antigen (capsular antigens), F antigen (fimbrial), M antigen and R antigen (in S R mutation due to the loss of O antigens).
  • Salmonella Paratyphi causes paratyphoid.
  • Salmonella Typhi differs from Salmonella Paratyphi in TSI reactions on the basis of H2S production (S. Typhi) and gas formation (S. paratyphi).

Salmonella Footages

Gram-negative rods of S. Typhi in Gram staining of culture

Fig. Gram-negative rods of Salmonella Typhi in Gram staining of culture at a magnification of 1000X

S. Typhi Growth on BHI Broth (Blood Culture Bottle)

Fig. S. Typhi Growth on BHI Broth (Blood Culture Bottle)

Salmonella Typhi Colony Morphology on Nutrient Agar

Fig. S. Typhi Colony Morphology on Nutrient Agar

Salmonella Typhi Colony Characteristics on Blood Agar

Fig. S. Typhi Colony Characteristics on Blood Agar

Salmonella non-lactose fermenter colony on MacConkey medium

Fig. Salmonella non-lactose fermenter colony on MacConkey medium

Salmonella Typhi (black colony) and Salmonella Paratyphi colony on XLD agar expo

Fig. S. Typhi (black colony) and Salmonella Paratyphi colony on XLD agar expo

Salmonella Typhi biochemical reactions in TSI, SIM, citrate, and urea agar

Fig. S. Typhi biochemical reactions in TSI, SIM, urea, and citrate agar

Salmonella Paratyphi biochemical reactions in TSI, SIM, urea agar, and citrate medium

Fig. Salmonella Paratyphi biochemical reactions in TSI, SIM, urea agar, and citrate medium

S. Typhi Details

Fig. S. Typhi Growth on Nutrient agar, Blood agar, MacConkey medium, BHI broth and biochemical assays in TSI, SIM, Citrate, and urea agar

Further Readings

  • Cowan and Steel’s, manual for the identification of medical bacteria
  • Topley and Wilson’s microbiology and microbial infection Topley and Wilson’s microbiology and microbial infection – Bacteriology-2-10th Edn.
  • Manual of Clinical Microbiology   -Patrick R. Murray -8th Edn.
  • Bailey and Scott’s  Diagnostic Microbiology -13th Edn.
  • Mackie & Mc Cartney  Practical Medical Microbiology- 14th  Edn.
  • Diagnostic Microbiology -Connie R. Mahon & George Manuselis
  • Koneman Color Atlas and Textbook of Diagnostic Microbiology-6th  Edn.
  • Jawetz Melnick and Adelberg’s Medical Microbiology- 25th Edn.
  • Lippincott’s –Illustrated- review-Microbiology-3rd Edn.
  • Mandell’s Infectious Disease-7th Edn.
  • Bergey’s Manual of Systemic Bacteriology – 2nd  Edn.
  • Text Book of Microbiology -Anantanarayan & Paniker-9th Edn.
Medical Lab Notes

View Comments

  • You could definitely see your expertise in the work you write. The world hopes for more passionate writers like you who aren't afraid to say how they believe. Always follow your heart.

  • Good write-up, I?¦m normal visitor of one?¦s website, maintain up the excellent operate, and It is going to be a regular visitor for a lengthy time.

  • Perfect piece of work you have done, this internet site is really cool with fantastic information.

  • I am now not sure where you're getting your information, but great topic. I needs to spend a while studying more or working out more. Thanks for magnificent information I was in search of this info for my mission.

  • wonderful put up, very informative. I ponder why the other specialists of this sector do not understand this. You must continue your writing. I am confident, you have a huge readers' base already!

  • There are some fascinating points in time on this article however I don’t know if I see all of them middle to heart. There's some validity but I will take maintain opinion until I look into it further. Good article , thanks and we would like more! Added to FeedBurner as well

  • I was very pleased to find this web-site.I wanted to thanks for your time for this wonderful read!! I definitely enjoying every little bit of it and I have you bookmarked to check out new stuff you blog post.

  • Once I originally commented I clicked the -Notify me when new feedback are added- checkbox and now each time a comment is added I get four emails with the identical comment. Is there any method you can take away me from that service? Thanks!

Share
Published by
Medical Lab Notes

Recent Posts

Transforming Infectious Disease Diagnostics with tNGS Technology

In the world of modern diagnostics, speed, accuracy, and comprehensiveness are critical—especially when dealing with…

3 days ago

Revolutionizing Molecular Diagnostics: A Look Inside Bioeksen’s Innovative Solutions

Introduction In today’s rapidly evolving healthcare landscape, the demand for fast, accurate, and accessible diagnostic…

3 days ago

Unmasking Fungal Pathogens: A Deep Dive into the MYCOscreen18 PCR Panel

Introduction to MYCOscreen18 PCR Panel Identifying fungal infections quickly and accurately is a critical challenge…

3 days ago

Multiplex Real-Time PCR in Infectious Disease Diagnostics: A New Era of Rapid and Comprehensive Detection

The increasing burden of infectious diseases demands diagnostic solutions that are not only rapid but…

3 days ago

Advanced Molecular Fungal Diagnostics: Bridging the Gap in Clinical Mycology

Fungal infections represent a growing global health challenge, causing over 1.7 million deaths annually, with…

3 days ago

Klebsiella aerogenes : Introduction, Morphology, Pathogenicity, Lab Diagnosis, Treatment, Prevention, and Keynotes

Introduction Klebsiella aerogenes (formerly Enterobacter aerogenes) is an opportunistic Gram-negative, facultative anaerobic bacterium responsible for serious healthcare-associated infections…

2 weeks ago