Many strains of Brucella, notably the American Br. suis types are capable of
hydrolyzing urea to form CO₂ and NH₃ The reaction can proceed to the formation
of ammonium carbonate. The methods at present in use for measuring urease activity to Brucella strains are either rather inaccurate or require specialized equipment (Wohlfeil & Weiland,1927; Piishel, 1936; Ferguson & Hook, 1943; Schneider & Gunderson, 1946; Christensen, 1946; Bauer, 1949; Hoyer, 1950 ; Pacheco & Thiago de Mello, 1950; Sanders & Warner, 1951; Renoux & Quatrefages, 1951; Huddleson, 1951; Pickett, Nelson & Liberman, 1953; Niznansky & Kremery, 1953; Godgluck & Marggraff,1955). In addition they expose workers to infection with virulent material, e.g. the use of the Warburg apparatus, or Van Slyke & Archibald's (1944) titrimetric method or Conway's (1939) microdiffusion method.
For these reasons the Joint FAO/WHO Expert Committee on Brucellosis feels
that if the urease test is to be of real value, it should be improved (1953).
In this report the work carried out at the Onderstepoort centre leading to the
institution of a routine pH threshold urease test, will be recorded. This test is
reliable and the results can be presented numerically.