Thermo Scientific™ Vogel Johnson Agar

Description

Detect coagulase-positive, mannitol fermenting strains of Staphylococcus aureus from contaminated foods and clinical specimens using Thermo Scientific™ Remel™ Vogel-Johnson Agar. In 1955, Zebovitz et al. developed Tellurite-Glycine Agar as a selective medium for the detection of coagulase-positive staphylococci¹. Vogel and Johnson increased the mannitol content and added phenol red as a pH indicator to create Vogel-Johnson Agar². This agar is recommended by Association of Official Analytical Chemists (AOAC) for food bacteriology^3,4.

Staphylococcus is a common cause of food poisoning due to production of enterotoxins. Staphylococcus aureus is a gram-positive bacteria that causes a wide variety of clinical diseases. Infections caused by this pathogen are common both in community-acquired and hospital-acquired settings.

Vogel-Johnson Agar, by selectively identifying coagulase-positive and mannitol-fermenting strains, permits the early detection of Staphylococcus aureus from heavily contaminated foods and clinical specimens.

• Ready to use – Convenience of a prepared media
• Selective – Potassium tellurite, lithium chloride and glycine act as selective agents which inhibit non-staphylococcal organisms, including many gram-negative and gram-positive bacteria.
• Easy to interpret – Coagulase-positive staphylococci ferment mannitol to form yellow zones around the colonies. S. aureus reduces potassium tellurite to metallic tellurium resulting in black colonies.
• Recommended by AOAC – For isolation of staphylococci from food sources^3,4.

This medium contains casein peptone that provides essential amino acids, peptides, and nitrogen essential for the growth of bacteria. Yeast extract supplies essential B-complex vitamins. Potassium tellurite, lithium chloride and glycine are selective agents which inhibit non-staphylococcal organisms, including many gram-negative and gram-positive bacteria. Phenol red is the pH indicator and agar is the solidifying agent.

The fermentation of mannitol by coagulase-positive staphylococci is indicated by development of yellow zones surrounding the colonies. This is caused by a pH change, resulting in the phenol red indicator turning from red to yellow.

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Remel™ and Oxoid™ products are now part of the Thermo Scientific brand.