This monograph has been assessed by members of the IUMS–ICFMH Working Party on Culture Media and given ‘Approved’ status.

CATC agar is a selective medium for the isolation and cultivation of enterococci. High concentrations of citrate and azide achieve almost complete suppression of other bacterial flora and allow good growth of enterococci (Enterococcus faecalis spp. and Enterococcus faecium) (Reuter, 1968, 1978, 1985).

Suspend the ingredients, except those marked *, in the water and heat to boiling to dissolve completely. Sterilise in the autoclave for 15 min at 121°C. Cool to about 50°C and add 20 mL of 10% solution of sodium carbonate (prepared in sterile water without heating), 10 mL of 1% solution of 2,3,5-triphenyltetrazolium chloride and 4 mL of 10% solution of sodium azide. Adjust pH to 7.0±0.1 at 50°C. Distribute into sterile Petri dishes.