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HardyCHROM™ Listeria, a chromogenic medium for Listeria monocytogenes, 15x100mm plate, order by the package of 10, by Hardy Diagnostics.

HardyCHROM™ Listeria is a chromogenic medium recommended for the selective isolation, differentiation, and enumeration of Listeria monocytogenes from food and environmental samples by colony color and appearance. L. monocytogenes colonies will turn turquoise with a distinctive white halo.


  • Modified and improved ALOA formula
  • Differentiates L. monocytogenes and L. ivanovii from other Listeria species
  • Colonies turn turquoise with a white halo for easy read-out
  • Results as early as 24 hours
  • Economically priced


Listeria are gram-positive, non-sporing bacilli. They are ubiquitous in nature and can be isolated from soil, vegetables, and natural waters as well as from healthy animals and humans. While many species are non-pathogenic, Listeria monocytogenes is a well-established food poisoning risk. It can be found in uncooked meats and vegetables, as well as unpasteurized dairy products. Its ability to cause disease is due, in part, to the bacterium's ability to survive and grow at refrigerated temperatures. Clinical symptoms can range from flu-like illness to more serious conditions including meningitis, pneumonitis, septicemia and endocarditis. Listeria monocytogenes infections mainly occur in neonates, pregnant women, the elderly and immunocompromised individuals. Infections in pregnant women are a documented cause of spontaneous abortions and still births.

HardyCHROM™ Listeria is a chromogenic medium that allows for the rapid and reliable detection of Listeria monocytogenes. Current isolation methods for L. monocytogenes require multiple media types and can require up to 10 days of incubation. With HardyCHROM™ Listeria, there is only a single broth enrichment step for a total incubation time of 48-72 hours.

HardyCHROM™ Listeria contains specific chromogenic substrates that result in all Listeria species producing turquoise colored colonies when the substrate is hydrolyzed by specific enzymes. Further, this medium is able to detect the phospholipase activity specific to the two pathogenic Listeria species: L. monocytogenes and L. ivanovii. These two species will produce turquoise colored colonies surrounded by an opaque white halo within 48 hours. While L. ivanovii is rare in clinical samples, further tests are needed to definitively differentiate between these two species. Organisms other than Listeria are inhibited or grow as colorless or turquoise colonies without halos.

  • See the Instructions For Use (IFU) below (under Technical Information) for the complete procedure with color photos.

  • Hardy Diagnostics was the first company to introduce chromogenic prepared media to the United States in 1996. You can expect Hardy Diagnostics to be the leading innovator in chromogenic detection methods.

  • We offer a handy bench-top flip chart to help you interpret the colors of all our chromogenic media. Please call us to receive your copy! (800) 266-2222.

  • We believe in good patient care, just like you do. Look to Hardy and experience "a culture of service."

    This media is to be stored and incubated in the dark. If you have a light in your refrigerator, incubator, or you leave the media exposed to light on the bench top, Hardy Diagnostics offers free Blok-Boxes. Blok-Box is a reusable cardboard box that holds one sleeve of ten petri plates.

    Please ask Customer Service if you would like a free Blok-Box sent with your order. Customer Service – (800) 266-2222

  • To order this product, enter the quantity you wish to order in the QTY field and click the shopping cart icon. When finished, click My Shopping Cart to proceed to checkout or Continue Shopping to shop for more products.

    Cat No. Description Price Curr UOM Qty  
    G317 HardyCHROM Listeria
    HDx, 15x100mm plt 10/pk R
    $36.05 USD PK10

    Manufacturer Category Organism
    Hardy Diagnostics: prepared media

    Media, Prepared

    Listeria monocytogenes

    Instructions for Use Video SDS


    Brochures and Studies BioSafety Level


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