Gram Negative Bacteria Biochemical Test: Table, Introduction, Common Tests with Short Description, List of Organisms, and Related Pictures

Common Gram Negative Bacteria Biochemical Test Table

Introduction of Gram-Negative Bacteria Biochemical Test

‘Common Gram Negative Bacteria Biochemical Test’ is a genuine puny collection of clinically relevant bacteria isolated in the clinical bacteriology laboratory by the creator and those etiological agents captured in his camera are only included.

Common Tests of Gram-Negative Bacteria

1. Triple Sugar Iron (TSI) Agar Test
2. Motility Indole Urea (MIU) Test
3. Citrate Utilization Test
4. Oxidase Test

Key

1. – is a Negative Result
2. + is a Positive Result
3. d is different strains give different Results
4. ± Positive Or Negative Result
5. R is Red in color
6. NC is no change in color
7. Y is Yellow in color
8. W is weak Positive
9. S is slow

Common Tests with Short Description

• Lactose fermenting looks different on different media, In MacConkey agar lactose fermenting organisms are pink in color.

• Citrate Test: Growth on the medium with color change from green to intense blue is positive and positive bacteria are Klebsiella pneumoniae, Citrobacter freundii, Enterobacter cloacae (a minority of strains gives negative result), Salmonella other than Typhi and Paratyphi A, Serratia marcescens, Proteus mirabilis(a minority of strains gives negative results), Providencia alcalifaeciens, Vibrio vulnificus, Euringella American and Achromobacter oxylosoxidans.

• Motility: Spreading growth in inoculum is Motile. Diffused growth or turbidity extends away from the stab inoculation line in the case of motile organisms while non-motile organisms appear as restricted growth along the stab line and positive organisms are E. coli, Salmonella  Typhi, Salmonella Paratyphi A, Citrobacter freundii, Citrobacter koseri, Enterobacter spp., Serratia marcescens, Proteus vulgaris, Proteus mirabilis, Morganella morganii, Providencia alcalifaciens, Providencia stuartii, Providencia rettgeri, Yersinia enterocolitica, Vibrio cholerae,Vibrio parahaemolyticus, Pseudomonas aeruginosa, and Alcaligenes spp.

Microscopic-Based Motility of Bacteria Demonstration

• Indole Test: Red-colored ring after the addition of Kovac’s reagent is positive and positive bacteria are Escherichia coli, Klebsiella oxytoca, Proteus vulgaris, Morgenella morganii, Vibrio cholerae, Providencia species.

• Urea test: Red color is positive and positive organisms are Proteus vulgaris, Proteus mirabilis,Morganella morganii, Providencia rettgeri, etc.

• H₂S: Blackening is Positive. Hydrogen Sulfide is produced by the action of the bacteria with sodium Thiosulphate. This is detected by the reduction of ferric ions to produce a black precipitate. Positive bacteria are Salmonella Typhi,Citrobacter freundii, Proteus vulgaris, and Proteus mirabilis.

• Gas: Gas production from sugar fermentation is indicated by bubbles, the fracturing of the medium, or displacement of the medium. Gas-forming organisms are Escherichia coli, Klebsiella pneumoniae, Salmonella Paratyphi, Citrobacter fruendii, C. koseri, Enterobacter species, etc.

• Oxidase: Deep blue to purple color is Positive. Positive bacteria are seudomonas, Aeromonas, Vibrio, Brucella, Haemophilus, Alcaligenes, Neisseria, Campylobacter, and Pasteurella.

List of Common Bacteria Biochemical Test Demonstration

• E. coli
• Shigella dysenteriae
• Shigella flexneri
• Shigella boydii
• Shigella sonnei
• Salmonella Typhi
• Salmonella Paratyphi A
• Citrobacter freundii
• Citrobacter koseri
• Klebsiella pneumoniae subsp. pneumoniae
• Klebsiella aerogenes (formerly Enterobacter aerogenes)
• Klebsiella oxytoca
• K. pneumoniae subsp.ozaenae
• K. pneumoniae subsp.rhinoscleromatis
• Enterobacter spp.
• Serratia marcescens
• Proteus vulgaris
• Proteus mirabilis
• Morganella morganii
• Providencia alcalifaciens
• Providencia stuartii
• Providencia rettgeri
• Yersinia enterocolitica
• Vibrio cholerae
• Vibrio parahaemolyticus
• Pseudomonas aeruginosa
• Acinetobacter spp.
• Alcaligenes spp.

Related Pictures

E. coli  biochemical tests in TSI, SIM, Urea, and Citrate agar

Shigella biochemical tests in TSI, SIM, Urea, and Citrate agar

Salmonella Typhi biochemical tests in TSI, SIM, Urea, and Citrate agar

Salmonella Paratyphi biochemical tests in TSI, SIM, Urea, and Citrate agar

Klebsiella pneumoniae biochemical tests in TSI, SIM, Urea, and Citrate agar

Klebsiella oxytoca biochemical tests in TSI, SIM, Urea, and Citrate agar

Proteus mirabilis biochemical tests in TSI, SIM, Urea, and Citrate agar

Serratia marcescens biochemical tests in TSI, SIM, Urea, and Citrate agar

Pseudomonas aeruginosa biochemical tests in TSI, SIM, Urea, and Citrate agar

Acinetobacter lwoffii biochemical tests in TSI, SIM, Urea, and Citrate agar

Further Readings 

1. Cowan & Steel’s Manual for identification of Medical Bacteria. Editors: G.I. Barron & R.K. Felthani, 3rd ed 1993, Publisher Cambridge University Press.
2. Bailey & Scott’s Diagnostic Microbiology. Editors: Bettey A. Forbes, Daniel F. Sahm & Alice S. Weissfeld, 12th ed 2007, Publisher Elsevier.
3. 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.
4. Colour Atlas and Textbook of Diagnostic Microbiology. Editors: Koneman E.W., Allen D.D., Dowell V.R. Jr, and Sommers H.M.
5. 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.
6. 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.
7.  Textbook of Diagnostic Microbiology. Editors: Connie R. Mahon, Donald G. Lehman & George Manuselis, 3rd edition2007, Publisher Elsevier.