[The New Dutch Kidney Test. I. Description of the method]

The New Netherlands Kidney test is designed for the detection of antibacterial residues in slaughtered animals. It is a single-plate system in which the culture medium used is composed of Standard II nutrient agar, supplemented with 1 per cent of NaCl, 1 per cent of dextrose, 0.2 per cent of KH2PO4 and 0.28 per cent of Na2HPO4.12H2O. After autoclaving, this medium is cooled to 55 degrees C, which is followed by the addition of trimethoprim (0.12 microgram/ml of agar) and spores of Bacillus subtilis BGA (10(4) ml of agar). The pH should be adjusted to 7.00 +/- 0.05, the prepared medium then being poured out into plates specially designed for this purpose, in such a manner that the thickness of the layer of agar is 2.2 mm throughout. The following method is used in examining slaughtered animals for the presence of residues showing antibacterial activity. Four paper discs are placed in the renal pelvis for a minimum period of thirty minutes; two discs impregnated with fluid from the renal pelvis are frozen at -20 degrees C for possible re-inspection and the other two are laid diagonally on a test plate. 25 microliter of a trimethoprim solution (containing 2 micrograms of TMP per ml of a 10 per cent NaCl solution) are dropped on each of the two last-named discs. The test plates are incubated at 37 degrees C for a period ranging from thirteen to eighteen hours.(ABSTRACT TRUNCATED AT 250 WORDS)