Proteus mirabilis: Introduction, Identification Features, Keynotes, and Proteus Footages

Introduction of Proteus mirabilis

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 mirabilis is naturally found in the natural environment and also 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 mirabilis

Basic Features	Properties
1. Gram Staining	Gram-Negative Rods (GNRs)
2. Spore	Non-Sporing
3. Capsule	Negative
4. Motility	Motile
5. Pigment	Negative
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 characters 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 using successfully to determine the relationship between strains of Proteus species in studies of cross-infection.
• 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 growth plate as shown in footages.
• Swarming growth of Proteus inhibited by following agents-

1. Agar (6%)
2. Sodium azide (NaN3) (1:500)
3. Chloral hydrate (1:500)
4. Boric acid (1:1000)
5. Alcohol (5-6%)

Proteus Footages

Proteus mirabilis non-lactose fementing colony on MacConkey agar

Proteus mirabilis in Gram staining of culture showing Gram-negative small to large rods or bacilli

Proteus mirabilis biochemical reactions in TSI, MIU and citrate agar

Antibiotic Sensitivity Testing (AST) Pattern of Proteus mirabilis

Swarming growth of Proteus on blood agar

Dienes Phenomenon of Proteus mirabilis with different strains

Swarming growth of Proteus inhibiting agents

Proteus made ‘Natural Bacterial Agar Art’

Further Reading

1. https://jb.asm.org/content/195/6/1305
2. https://www.karger.com/Article/FullText/514097
3. https://www.annualreviews.org/doi/pdf/10.1146/annurev.mi.32.100178.000533
4. https://universe84a.com/proteus-general-characteristics
5. Williams FD, Schwarzhoff RH. 1978. Nature of the swarming phenomenon in Proteus. Annu. Rev. Microbiol. 32:101–122.
6. https://www.sciencedirect.com/topics/medicine-and-dentistry/proteus-mirabilis
7. Armbruster CE, Mobley HLT. 2012. Merging mythology and morphology: the multifaceted lifestyle of Proteus mirabilis. Nat. Rev. Microbiol. 10:743–754
8. Morgenstein RM, Szostek B, Rather PN. 2010. Regulation of gene expression during swarmer cell differentiation in Proteus mirabilis. FEMS Microbiol. Rev. 34:753–763.
9. Rather PN. 2005. Swarmer cell differentiation in Proteus mirabilis. Environ. Microbiol. 7:1065–1073.
10. Bailey & Scott’s Diagnostic Microbiology. Editors: Bettey A. Forbes, Daniel F. Sahm & Alice S. Weissfeld, 12th ed 2007, Publisher Elsevier.
11. 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.
12. Colour Atlas and Textbook of Diagnostic Microbiology. Editors: Koneman E.W., Allen D.D., Dowell V.R. Jr, and Sommers H.M.
13. Textbook of Diagnostic Microbiology. Editors: Connie R. Mahon, Donald G. Lehman & George Manuselis, 3rd edition 2007, Publisher Elsevier
14. 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.
15. 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.
16. 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