Indole-Positive Bacteria Bacteria that test positive for cleaving indole from tryptophan include: Aeromonas hydrophila, Aeromonas punctata, Bacillus alvei, Edwardsiella sp., Escherichia coli, Flavobacterium sp., Haemophilus influenzae, Klebsiella oxytoca, Proteus sp.

What molecule do indole positive bacteria?

The indole test is a biochemical test performed on bacterial species to determine the ability of the organism to split indole from the amino acid tryptophan. This division is performed by a chain of a number of different intracellular enzymes, a system generally referred to as "tryptophanase."

Which reaction is positive in this indole test?

Indole Spot Reagent Result

Positive reaction: The development of a blue colour within 3 minutes. Negative reaction: The development of a pink colour within 3 minutes.

What does a positive indole test mean?

A positive indole test is indicated by the formation of a red color in the reagent layer on top of the agar deep within seconds of adding the reagent. If a culture is indole negative, the reagent layer will remain yellow or be slightly cloudy.

Is Proteus indole positive?

Other Proteus spp. are indole positive, e.g., P. vulgaris and P. penneri.

Indole Test

42 related questions found

Is Citrobacter indole positive?

Citrobacter amalonaticus is typically positive for indole production, negative for H₂S production on TSI agar, and grows in KCN. It utilizes citrate but does not ferment malonate.

Is Enterobacter aerogenes indole positive?

E. coli is indole-positive; Enterobacter aerogenes is indole- negative. Glucose is the major substrate oxidized by enteric bacteria for energy production.

Is Shigella indole positive?

In the case of Shigella, the indole reaction is consistently negative only in specific serotypes within each traditional species of Shigella, including 7 of the 10 S. dysenteriae serotypes, 9 of the 15 S. boydii serotypes, 1 of the 6 S.

Is Staphylococcus indole positive?

aureus isolates, 17 (85%) were found as positive for coagulase, catalase, methylene red, Voges-proskauer and hemolysis tests and negative for oxidase and indole tests. They also produce acid from glucose, lactose and sucrose.

Is Pseudomonas indole positive?

Pseudomonas species also typically give a positive result to the oxidase test, the absence of gas formation from glucose, glucose is oxidised in oxidation/fermentation test using Hugh and Leifson O/F test, beta hemolytic (on blood agar), indole negative, methyl red negative, Voges–Proskauer test negative, and citrate ...

Which molecule do indole positive cleave to form indole?

Indole is generated by reductive deamination from tryptophan via the intermediate molecule indolepyruvic acid. Tryptophanase catalyzes the deamination reaction, during which the amine (-NH₂) group of the tryptophan molecule is removed. Final products of the reaction are indole, pyruvic acid, ammonium (NH₄⁺) and energy.

How does the indole test work?

The indole test is a qualitative procedure for determining the ability of bacteria to produce indole by deamination of tryptophan. Using Kovacs method, indole combines, in the presence of a tryptophan rich medium, with p-Dimethylaminobenzaldehyde at an acid pH in alcohol to produce a red-violet compound.

Is Klebsiella indole positive or negative?

The two clinically relevant species, Klebsiella pneumoniae and Klebsiella oxytoca, are differentiated by the ability to produce indole from tryptophan, K. oxytoca being indole positive.

Is Salmonella indole negative?

Salmonellae yield negative Voges-Proskauer and positive methyl red tests and do not produce cytochrome oxide. Salmonellae are also unable to deaminate tryptophan or phenylalanine and are usually urease and indole negative. Based on the biochemical tests above, Salmonella can presumptively be identified.

Is Salmonella typhi citrate positive?

When Simmons Citrate agar is inoculated with Salmonella typhimurium , the medium turns royal blue. This is a positive result for the citrate test. When Simmons Citrate agar is inoculated with Escherichia coli , the medium remains green. This is a negative result for the citrate test.

Is bacillus catalase positive or negative?

Purpose or Uses of Catalase Test

It is used to differentiate aerotolerant strains of Clostridium, which are catalase negative, from Bacillus species, which are positive.

Is Escherichia catalase positive?

Escherichia coli and Streptococcus pneumoniae have been used as model catalase-positive and catalase-negative bacteria, respectively.

Which medium is used for indole test?

The medium used with this reagent is either broth containing tryptophan, motility- indole-ornithine agar, or sulfide-indole-motility agar (SIM).

Are Enterobacteriaceae catalase positive?

Enterobacter species

Colonies of Enterobacter strains may be slightly mucoid. They are catalase positive and oxidase negative. Nitrates are also reduced. They also ferment glucose and lactose with the production of acid and gas.

Is K Aerogenes oxidase positive?

Klebsiella aerogenes, previously known as Enterobacter aerogenes, is a Gram-negative, oxidase negative, catalase positive, citrate positive, indole negative, rod-shaped bacterium.

Is Enterobacter Gram positive or negative?

Enterobacteriaceae are a large family of Gram-negative bacteria that includes a number of pathogens such as Klebsiella, Enterobacter, Citrobacter, Salmonella, Escherichia coli, Shigella, Proteus, Serratia and other species.

Is Citrobacter Freundii Gram positive or negative?

freundii complex organisms. Citrobacter spp. are gram-negative bacilli in the family Enterobacteriaceae.