Evaluation of Two Spot-Indole Reagents

Lowrance, B. L.; Reich, P.; Traub, W. H.

doi:10.1128/aem.17.6.923-924.1969

Cited by 12 publications

(6 citation statements)

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“…Three biochemical tests, Voges-Proskauer (VP) ( 48 ), lysine decarboxylase ( 49 ), and indole ( 50 ), were used to confirm the evidence of the presence of enteric bacteria and to differentiate E. coli from other Enterobacteriaceae ( 51 ). The presumptive E. coli isolates were grown (i) in methyl red-VP (MR-VP) medium (Difco) and tested for acetoin production using Voges-Proskauer reagent (BioMérieux) according to the manufacturer’s instructions, (ii) on decarboxylase medium base (Difco) supplemented with l -lysine (Sigma) to test for l -lysine utilization, and (iii) in L-broth to test for tryptophan utilization using Remel indole reagent (Thermo Scientific) according to the manufacturer’s instructions.…”

Section: Methodsmentioning

confidence: 99%

Responses of the Human Gut Escherichia coli Population to Pathogen and Antibiotic Disturbances

et al. 2018

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Research on human-associated E. coli tends to focus on pathogens, such as enterotoxigenic E. coli (ETEC) strains, which are a leading cause of diarrhea in developing countries. However, the severity of disease caused by these pathogens is thought to be influenced by the microbiome. The nonpathogenic E. coli community that resides in the human gastrointestinal tract may play a role in pathogen colonization and disease severity and may become a reservoir for virulence and antibiotic resistance genes. Our study used whole-genome sequencing of E. coli before, during, and after challenge with an archetype ETEC isolate, H10407, and antibiotic treatment to explore the diversity and resiliency of the resident E. coli population in response to the ecological disturbances caused by pathogen invasion and antibiotic treatment.

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Section: Methodsmentioning

confidence: 99%

Responses of the Human Gut Escherichia coli Population to Pathogen and Antibiotic Disturbances

et al. 2018

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“…The DMACA reagent proved to be the most sensitive spot-test indicator of indole production in this study, and was shown to be more sensitive than DMABA with facultative bacteria by Lowrance and coworkers. 1 We observed also that in tests with Bacteroides melaninogenicus, the black pigment which was not apparent while growth was on the solid medium became obvious on the test papers and obscured the pink to red color reaction with Kovacs', DMABA, and Patho-Tec I strips. The blue or green reaction with DMACA spread away from the blackened cellular material and was easy to see.…”

Section: Discussionmentioning

confidence: 62%

Evaluation of Media and Reagents for Indole-spot Tests in Anaerobic Bacteriology

Sutter

Carter

1972

Am J Clin Pathol

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Sutter, Vera L., and Carter, Walker T.: Evaluation of media and reagents for indole-spot tests in anaerobic bacteriology. Am. J. Clin. Pathol. 58: 335-338, 1972. Indole-spot tests for use in anaerobic bacteriology were evaluated. Spot test results obtained with four reagents and 143 anaerobic organisms grown on blood agars prepared with three commonly-used bases were compared with those obtained with a tube test utilizing indole-nitrate medium and Kovacs' test. Correlation of spot test with tube test results was best when organisms were grown on trypticase soy blood agar and tested with 1% p-dimethylaminocinnamaldehyde in 10% (v/v) concentrated hydrochloric acid. This indole-spot test offers a simple, reliable, economical, and rapid method for detection of indole production with anaerobic bacteria.

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“…The azafulvenium chloride salt, in aqueous solutions, absorbs in the visible region (500-700 nm) with a maximum centered at 624 nm and displays a high extinction coefficient value (86,666 mol −1 • L• cm −1 [18], 97,000 ± 13,000 mol −1 • L• cm −1 (this work)). In the presence of tryptophan, another condensation reaction occurs, which yields a red-violet product, absorbing at 563 nm [19]. In culture media, such as Lysogenic Broth or Buffered Peptone Water, which both contain tryptophan, both reactions occur and the absorption bands of the two products overlap.…”

Section: Probe Choice and Interferencesmentioning

confidence: 99%

Discriminating Bacteria with Optical Sensors Based on Functionalized Nanoporous Xerogels

et al. 2014

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International audienceAn innovative and low-cost method is proposed for the detection and discrimination of indole-positive pathogen bacteria. The method allows the non-invasive detection of gaseous indole, released by bacteria, with nanoporous colorimetric sensors. The innovation comes from the use of nanoporous matrices doped with 4-(dimethylamino)-cinnamaldehyde, which act as sponges to trap and concentrate the targeted analyte and turn from transparent to dark green, long before the colonies get visible with naked eyes. With such sensors, it was possible to discriminate E. coli from H. alvei, two indole-positive and negative bacteria after seven hours of incubation

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Evaluation of Two Spot-Indole Reagents

Abstract: Two spot-indole reagents, p-dimethylaminobenzaldehyde (DMABA) and pdimethylaminocinnamaldehyde, were evaluated quantitatively. Although fourfold less sensitive, DMABA proved to be more stable and economical.

Cited by 12 publications

References 0 publications

Responses of the Human Gut Escherichia coli Population to Pathogen and Antibiotic Disturbances

Responses of the Human Gut Escherichia coli Population to Pathogen and Antibiotic Disturbances

Evaluation of Media and Reagents for Indole-spot Tests in Anaerobic Bacteriology

Discriminating Bacteria with Optical Sensors Based on Functionalized Nanoporous Xerogels

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