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Harlequin™ Chromogenic Coliform Agar

Productcode: NCM1005A OLD HAL016
Supplier: Neogen
Package size: 500 g

Product information

Chromogenic Coliform Agar (CCA) is recommended by ISO 9308-1 for the simultaneous detection and enumeration of β-glucuronidase-positive Escherichia coli and β-D-galactosidase positive coliform bacteria using membrane filtration from water samples.

Peptone and yeast extract provide a source of nitrogen and essential vitamins. Sodium chloride maintains the osmotic balance and the phosphates buffer the media. Sodium Pyruvate, Sorbitol and Tryptophan aid in the recovery and detection of the target organisms.

Tergitol™ 7 is a surfactant that acts as a selective agent. The dual chromogens are incorporated to visualise enzyme expression. IPTG induces β-D-galactosidase and agar is the gelling agent. E.coli possess both β-D-galactosidase and β-glucuronidase activity so appear dark blue to violet. Coliform bacteria, that are not E.coli, possess only β-D-galactosidase so appear pink to red. Any organism able to grow that does not belong to these groups appears colourless.

This medium conforms to the performance requirements of ISO 9308-1 2017.

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For more information from Labema’s specialist. The specialist for this product is Iiris Ylöstalo.

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Researchs

Comparison of Four Chromogenic Media and Hektoen Agar for Detection and Presumptive Identification of Salmonella Strains in Human Stools
We compared the performance of four commercial chromogenic media—namely, ABC medium (Lab M. Ltd., Bury, United Kingdom), COMPASS Salmonella agar (Biokar Diagnostics, Beauvais, France), CHROMagar™ Salmonella agar (CHROMagar Company, Paris, France), and SM ID agar (bioMerieux, Marcy l’Etoile, France)— with conventional Hektoen medium. Nine hundred sixteen stool samples from inpatients at three hospitals were cultured, in parallel, on the five media, both by direct inoculation and after selective enrichment in selenite broth. The specificity of the four chromogenic media was better than 91% after incubation for 24 h (77.7% with Hektoen agar) and better than 84% after incubation for 48 h (74.8% with Hektoen agar). This higher specificity reduces the need for confirmatory tests, thereby cutting technical time and reagent requirements. Both COMPASS agar and CHROMagar™ Salmonella, which after simple additional tests showed close efficiencies (96 and 97%, respectively), can be recommended as single-plate media of choice for the detection and presumptive identification of salmonellae in stools.