InMicro® Dehydrated: Vogel-Johnson Agar

Isolate and presumptively identify Staphylococcus aureus from clinical specimens and food with InMicro® Dehydrated: Vogel-Johnson Agar. Staphylococcus aureus reduces tellurite to metallic tellurium in the medium and appear as black colonies.

Staphylococcus aureus is a Gram-positive, round-shaped bacteria and can cause skin and soft tissue infections such as abscesses (boils), furuncles, and cellulitis. Although most staph infections are not serious, S. aureus can cause serious infections such as bloodstream infections, pneumonia, or bone and joint infections.

Vogel-Johnson Agar allows the early detection and of Staphylococcus aureus from heavily contaminated foods and clinical specimens by selecting and identifying coagulase-positive and monitol-fermenting strains.

• Selective: tellurite, lithium chloride and the high glycine concentration inhibits most of the contaminating organisms.
• Easy-to-read: Staphylococcus aureus appear as black colonies due to their ability to reduce tellurite to metallic tellurium.
• Allows the early detection and of Staphylococcus aureus from heavily contaminated foods and clinical specimens by selecting and identifying coagulase-positive and monitol-fermenting strains.

Vogel and Johnson modified the Tellurite Glycine Agar formula of Zebovitz et al. by doubling the mannitol concentration to 1% (w/v) and adding Phenol Red as a pH indicator. The enhanced fermentation reaction which occurs as a result of the increase in mannitol content is clearly indicated by the development of yellow zones surrounding the colonies.

Prolonged incubation may result in the growth of black coagulase-negative colonies and if these organisms also ferment mannitol they may be falsely identified from their appearance as Staphylococcus aureus. In these circumstances, further tests of identity should be carried out before concluding that the organism is Staphylococcus aureus.