Campylobacter Culture Medium

Campylobacter Millichrome^™ plus Agar Base is a selective chromogenic culture medium intended for use in the qualitative direct detection, differentiation and presumptive identification of pathogenic biotypes of thermotolerant Campylobacter from food, animal feed, and environmental samples

The Campylobacter colonies are colored red after 48 h of incubation at an optimal growth temperature of 42°C, whereas the growth of other species is inhibited or forms blue or green colonies after incubation at the same temperature.

Campylobacter Millichrome^™ plus Agar Base is a selective media for the detection of thermotolerant Campylobacter. The distinguishing feature of these media is the inclusion of a chromogenic substrate mix that produces visible color changes upon the enzymatic activity of Campylobacter.Millichrome^™ chromogenic media is a specialized type of culture medium used to detect and isolate specific groups of bacteria based on their ability to produce enzymes with chromogenic substrates. Peptone and yeast extract provide nitrogenous nutrients for growth and other essential growth factors. Sodium chloride is needed for the osmotic balance. The chromogenic and selective mix contains chromogenic substrates for color differentiation based on the ability to cleave the substrate by characteristic enzymes. This mix contains as well selective agent that allows Campylobacter spp. to grow while other organisms are inhibited. Campylobacter Millichrome^™ plus Supplement gives additional selectivity to this medium. Agar is the solidifying agent.

Step 1 (Preparation of the base Campylobacter Millichrome^™ plus Agar Base):

• Disperse slowly 51.2 g of powder base in 1L of purified water.
• Stir until agar is well thickened.
• Heat and bring to boil (100 °C) while swirling or stirring regularly.

DO NOT HEAT TO MORE THAN 100 °C. DO NOT AUTOCLAVE AT 121 °C.
Warning: If using an autoclave, do so without pressure.
Advice: For the 100 °C heating step, mixture may also be brought to a boil in a microwave oven: after initial boiling, remove from oven, stir gently, then return to oven for short repeated bursts of heating until complete fusion of the agar grains has taken place (large bubbles replacing foam).

• Cool in a water bath to 45-50 °C. Swirl or stir gently to homogenize.

Step 2 (preparation of the supplement):

• In a transparent vessel, add 210 mg of Campylobacter Millichrome^™ plus Agar Base Supplement in 10 ml of purified water.
• Swirl well until complete dissolution.
• Filter to sterilize at 0.45 μm.
• Add the 10 ml of the supplement solution to the melted base (Step1) at 45-50 °C.
• Swirl or stir gently to homogenize.

Step 3 (pouring):

• Pour into sterile Petri dishes.
• Let it solidify and dry (longer than usual).

Store prepared media below 8°C, protected from direct light (max. 1 month). Store dehydrated powder, in a dry place, in tightly sealed containers at 2-25°C.

MilliChrome is a trademark of Merck KGaA, Darmstadt, Germany