The genus Proteus was discovered in 1885 by Hauser and it is also named after a Greek god. Proteus is a member of the family, Enterobacteriaceae and it is a Gram-negative, oxidase-negative, fimbriated, motile, non-sporing rod-shaped bacterium without capsule and having a size of 0.4–0.8 μm in diameter and 1.0–3.0 μm in length. Proteus vulgaris is naturally found in the natural environment and also in the intestinal tract. It is a gut bacterium inside our intestines whereas, outside the gut, it can cause serious infections. It is an etiological agent of catheter-associated UTI (CAUTI), sepsis, and septic shock if the infection goes up and causes cystitis and pyelonephritis.
Biochemical Reactions of Proteus vulgaris
Table of Contents
|1. Gram Staining||Gram-Negative Rods (GNRs)|
|6. Growth in potassium cyanide (KCN) medium||Positive|
|7. Catalase test||Positive|
|8. Oxidase test||Negative|
|9. Nitrate reduction test||Positive|
|10. MR (Methyl Red) test||Positive|
|11. VP (Voges- Proskauer) assay||Negative|
|12. OF (Oxidative-Fermentative) test||Fermentative (facultative anaerobes)|
|13. Gas from Glucose||Positive|
|14. H2S production||Positive|
|15. Indole formation||Negative|
|16. Urease/ urea hydrolysis test||Positive|
|17. Citrate/citrate utilization||Positive|
|18. DNase test||Variable|
|19. Glucose fermentation||Positive|
|20. Maltose fermentation||Negative|
|21. Lactose fermentation||Negative|
|22. Sucrose fermentation||Negative|
|23. Xylose fermentation||Positive|
|24. Mannitol fermentation||Negative|
|25. Acetate Utilization||Negative|
|26. ONPG (β-galactosidase)||Negative|
|27. Phenylalanine Deaminase (PDA)/PPA Test||Positive|
|28. Lipase test||Positive|
|29. Esculin Hydrolysis test||Negative|
|30. Lysine Decarboxylase Test||Negative|
|31. Ornithine Decarboxylase Test||Positive|
|32. Arginine Dihydrolase Test||Negative|
|33. Gelatin Hydrolysis||Positive|
|34. Tryptophan Deaminase||Negative|
|35. Casein Hydrolysis||Negative|
Keynotes on Proteus
- In Greek mythology, Proteus means sea god.
- Every year about 150 million people are affected by Proteus mirabilis globally.
- It is the bacterium of concern since, in the USA, it accounts for about 3% of all hospital infections and 44% of CAUTI.
- The principal virulence factors associated with infection are flagella, pili, urease, hemolysin, and metal intake.
- Multiple drug-resistant (MDR) strains to carry R plasmids have become very important in nosocomial infections.
- The distinctive characteristics of the genus are PPA, urease, and H2S positive.
- Indole helps to differentiate P. vulgaris (positive) from P. mirabilis ( negative).
- Dienes phenomenon or typing is used successfully to determine the relationship between strains of Proteus species in studies of cross-infection.
- The swarming growth of Proteus contains swimmer and swarmer cells and these cells can be determined using Gram’s staining i.e. swimmer cells- small-near the center of the growth plate while swarmer cells- large-away the center of the growth plate as shown in footages.
- The swarming growth of Proteus is inhibited by the following agents-
- Agar (6%)
- Sodium azide (NaN3) (1:500)
- Chloral hydrate (1:500)
- Boric acid (1:1000)
- Alcohol (5-6%)
Swarming growth of Proteus on blood agar
Proteus in Gram Staining
Proteus vulgaris Biochemical Tests-MIU, TSI, and Citrate Utilization Tests
Dienes phenomenon of Proteus vulgaris strains
Proteus mirabilis Biochemical Tests-MIU, TSI, and Citrate Utilization Tests
- Williams FD, Schwarzhoff RH. 1978. Nature of the swarming phenomenon in Proteus. Annu. Rev. Microbiol. 32:101–122.
- Armbruster CE, Mobley HLT. 2012. Merging mythology and morphology: the multifaceted lifestyle of Proteus mirabilis. Nat. Rev. Microbiol. 10:743–754
- Morgenstein RM, Szostek B, Rather PN. 2010. Regulation of gene expression during swarmer cell differentiation in Proteus mirabilis. FEMS Microbiol. Rev. 34:753–763.
- Rather PN. 2005. Swarmer cell differentiation in Proteus mirabilis. Environ. Microbiol. 7:1065–1073.
- Bailey & Scott’s Diagnostic Microbiology. Editors: Bettey A. Forbes, Daniel F. Sahm & Alice S. Weissfeld, 12th ed 2007, Publisher Elsevier.
- Clinical Microbiology Procedure Handbook, Chief in editor H.D. Isenberg, Albert Einstein College of Medicine, New York, Publisher ASM (American Society for Microbiology), Washington DC.
- Colour Atlas and Textbook of Diagnostic Microbiology. Editors: Koneman E.W., Allen D.D., Dowell V.R. Jr, and Sommers H.M.
- Textbook of Diagnostic Microbiology. Editors: Connie R. Mahon, Donald G. Lehman & George Manuselis, 3rd edition 2007, Publisher Elsevier
- Jawetz, Melnick and Adelberg’s Medical Microbiology. Editors: Geo. F. Brook, Janet S. Butel & Stephen A. Morse, 21st ed 1998, Publisher Appleton & Lance, Co Stamford Connecticut.
- Mackie and Mc Cartney Practical Medical Microbiology. Editors: J.G. Colle, A.G. Fraser, B.P. Marmion, A. Simmous, 4th ed, Publisher Churchill Living Stone, New York, Melborne, Sans Franscisco 1996.
- Manual of Clinical Microbiology. Editors: P.R. Murray, E. J. Baron, M. A. Pfaller, F. C. Tenover and R. H. Yolken, 7th ed 2005, Publisher ASM, USA