Common Bacteria Biochemical Test Demonstration: Introduction, Common

Common Bacteria Biochemical Test Demonstration: Introduction, Common Tests and List of Organisms

Introduction of Common Bacteria Biochemical Test Demonstration

‘Common Bacterial Biochemical Test Demonstration’ 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

Key

– is Negative Result
+ is Positive Result
d is different strains give different Result
± Positive Or Negative Result
R is Red in color
NC is no change in color
Y is Yellow in color
W is weak Positive
S is slow

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 extending 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.

Indole Test: Red-colored rink after 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.