This is a modification of Christensen’s urea base f
or the detection of rapid urease production by
spp. Other enterobacteria will split
the urea, but this will be delayed. This delay is a
chieved by the incorporation of glucose and the int
roduction of a buffering system into the
medium. The indicator for ammonia production is phe
Potassium dihydrogen phosphate
Agar No. 1
Method for reconstitution
Weigh 2.1 grams of powder, disperse in 95ml of deio
nised water. Allow to soak for 10 minutes, swirl to
mix, then sterilise at 121°C for 15
minutes. Allow to cool to 47°C, add aseptically 5ml
sterile urea solution X130/X135. Distribute into s
terile bottles and slopes, allow to set
in the sloped position.
Yellow/pale pink, translucent.
6.8 ± 0.2
Minimum Q.C. organisms:
ATCC 29906/WDCM 00023.
Storage of Prepared Medium:
Capped container – up to 1 month at 2-8°C in the da
Pure culture using straight wire for stab/streak te
37°C for 4-6 hours or overnight, aerobically.
Production of red colour in under 6 hours is positi
ve for rapid urease production.
Organism Growth Characteristics
Christensen, W.B. (1946). Urea decomposition as a m
eans of differentiating Proteus and paracolon cultu
res from each other and from
Salmonella and Shigella types. J. Bacteriol. 52: 46